J O U R N A L O F MILK TECHNOLOGY

Number 4

M A Y , 1938

Twenty-seventh Annual Meeting Cleveland, Ohio, October 19-21,1938 Headquarters, The Allerton

Official Publication of

INTERNATIONAL ASSOCIATION OF

MILK SANITARIANS II

dafe-Denosit Xaults!

As securely as a safe-deposit vault protects making it an absolutely sanitary closure^ money or jewels, a Welded Wire Seal pro­ Milk Sanitarians studying hood-capping tects the purity of milk. Like the lock are invited to write for free leaflets giv­ of a vault a Welded Wire Seal cannot be ing authoritative and helpful information tampered with, without instant detection. on this subject. Address your requests Notice how the long, sturdy hood com­ to Standard Cap and Seal Corporation, pletely covers the pouring lip of the bottle 1200 Fullerton Avenue, Chicago, Illinois.

IT’S SANITARY

THE STAN DAR D fUieMexUUibie, HOOD SEAL

THE NATIONAL TRADE MARK OF BETTER MILK AND CREAM Advertisements III

VITEX VITAMIN D MILK always has been marketed as a 400 USP unit per quart vitamin D milk. Assays to check this vitamin D po­ tency are conducted in accordance with state and local food control regulations.

Laboratories in the following colleges and universities are now cooperating with food control officials and with Vitex Laboratories, Inc., in conducting these assays:

Massachusetts State College, Amherst, Mass. Michigan State College, East Lansing, Mich. Ohio Experiment Station, Wooster, Ohio. New Jersey State College, New Brunswick, N. J. Iowa State College, Ames, Iowa. University of Nebraska, Lincoln, Nebr. Medical College of Virginia, Richmond, Va. Albany Medical College, Albany, N. Y. University of Louisville, Louisville, Ky. Pennsylvania State College, State College, Pa. Indiana University Medical School, Indianapolis, Ind. Tulane University, New Orleans, La.

VITEX LABORATORIES, INC. a Nopco Subsidiary Harrison, N. J.

When writing to advertisers, say you saw it in this Journal. IV Advertisements

Once the crimped edge is stretched by opening, it ISSju.: can’t be restored to its original snug fit. Tampering is betrayed. For full information and samples of all 1 £ C 0 ALUMINUM types of Alseco Aluminum Hoods, write a l u m i n u m s e a l co., 1347 Third Avenue, New Kensington, Pa. MILK BOTTLE HOODS

Advertising in the

Journal of M ilk Technology

carries your message to the

Leading Milk Sanitarians

and most progressive dairy companies thru the medium of their own journal

When writing to advertisers, say you saw it in this Journal. Advertisements V GENTLE HANDLING

Bottles Come Through _> Safe, Scratch-Free and CLEAN

Longer life to milk bottles is the plus feature of the CP Junior. To its regular job of turning out positively clean bottles in volume, this soaker-type washer adds a high degree of protection. After an operator loads the automatic feed, all handling is mechanical— the gentlest mechanical handling the industry affords. Practical elimination of breakage will mean a lot to some milk plants installing a CP Junior. But longer bottle life also means freedom from scratches which make "ground Junior glass" of the surface— a dull, clean but non-sparkling ex­ terior which does not do justice to the good milk inside. CP bottle pockets leave the outside open to soaking MILK action and jet scrubbing, but stops all abrasive action. Especially valuable is this protection for applied color let­ tering which adds advertising value to sparkling bottles. BOTTLE The CP Junior preserves it. Ask your CP representative about this washer which is the soaker-type but is not big and costly. Two sizes: 24-32 and 38-48. Send for WASHER descriptive bulletin. THE CREAMERY PACKAGE MFG. COMPANY 1243 WEST WASHINGTON BOULEVARD . . . - Chicago, Illinois Branches: Atlanta - Boston - Buffalo - Chicago - Dallas ■ Denver - Kansas City - Los Angeles Minneapolis ■ New York ■ Omaha - Philadelphia ■ Portland, Oregon - Salt Lake City San Francisco - Seattle - Toledo - Waterloo, Iowa CREAMERY PACKAGE MFG. CO. OF CANADA, LTD. THE CREAMERY PACKAGE MFG. COMPANY, LTD. 267 King St. West, Toronto, Ont., Canada Avery House, Clerkenwel! Green, London E. C. I., Eng.

When writing to advertisers, say you saw it in this Journal. VI Advertisements

m

• C O M P A C T • SIMPLE • ECONOMICAL • RUGGED • EFFICIENT • RUNNING IN OIL

Cberry-Burrell 6-16 Bottle Filler — capacity is 16 quarts per minute.

CHERRY - BURRELL SALUTES THE SMALLER MILK PLANT OPERATORS with a NEW BOTTLE FILLER BUILT ESPECIALLY FOR THEIR NEEDS

HE new 6-16 BOTTLE FILLER AND CAPPER by CHERRY-BURRELL has most of T the features of the larger fillers and cappers— yet is designed and priced for small milk plant owners having from 200 to 500-gallon capacities per day. Whether hand fed or with Automatic Bottje Conveyor Infeed from a Baltimore Soaker Type Washer the "6-16" efficiently fills and caps all products in any size standard milk bottles at the rate of 16 full quarts to the minute. Successful filling and capping of special products makes the "6-16" a most useful machine in large plants as well. Write us today for Bulletin No. G-319 which illus­ trates the 18 features of the new CHERRY-BURRELL 6-16 BOTTLE FILLER A N D CAPPER or call your nearest CHERRY-BURRELL sales office.

CrtERRY-BUr pell C o r p o r a t io n 427 w. R a n d o lp h S t., CHICAGO

When writing to advertisers, say you saw it in this Journal. JOURNAL OF MILK TECHNOLOGY

Official Publication of

The International Association of Milk Sanitarians

CONTENTS

Editorials ...... l Need for Official Supervision of Laboratories—Friend Lee Mickle...... 3 A Colorimeter For the Phosphatase Test—-W. H. Boynton and P. E. Nelbach...... 8 The Problem of Recontamination of Pasteurized Milk and Its Products—L. C. Bulmer ...... 10 Practical Farm Sterilization—Arthur H. Williamson ...... 14 New Creamery Butter Standards...... ——...... -...... 19 Report of the Committee on Ice Cream Sanitation—F. W. Fabian, Chairman...... 20 Filled Milk Decision ...... :...... 31 Modern Methods of Milk Plant Inspection—Maurice H. Shorago...... 32 Report of Committee on Laboratory Methods—A. H. Robertson, Chairman...... 36 An Evaluation of Some of the Tests Used in Detecting Mastitis in Dairy Cattle —A. C. Fay ...... :...... 38 What the Colleges are Doing in the Training of Milk Sanitarians—Fordyce Ely 43 Abstract of Proceedings of the Twenty-Ninth Annual Meeting of the American Butter Institute...... 46 Research with Cream at the Massachusetts State College—Merrill J. Mack...... 50 Information Concerning Journal of Milk Technology...... 53 Application Blank for Association Membership ...... 54 Constitution—International Association of Milk Sanitarians...... 55 Index to Advertisers ...... -...... VIII INTERNATIONAL ASSOCIATION OF MILK SANITARIANS

Secretary’s Office: State Department of Health, State Office Building, Albany, N.. Y.

OFFICERS 1937-1938 President, Alexander R. Tolland...... Boston, Mass. First Vice-President, Victor M. Ehlers...... Austin, Texas Second Vice-President, Paul B. Brooks, M. D...... Albany, N. Y. Third Vice-President, Leslie C. Frank...... Washington, D. C. Auditors: J. R. Jennings...... ^Chicago, 111. F. D. Holford ...... — ...... ______.New York City Secretary-Treasurer, C. Sidney Leete...... Albany, N. Y.

EXECUTIVE BOARD

The Executive Board consists of the Association President, the three Vice-Presidents, and the Secretary-Treasurer

COMMITTEES AND COMMITTEE CHAIRMEN COMMUNICABLE DISEASES AFFECTING MAN—Their Relation to Public Milk Supplies L A. Merchant, Chairman ...... Ames, Iowa DAIRY AND MILK PLANT EQUIPMENT Walter D. Tiedeman, Chairman...... Albany, N. Y. SANITARY PROCEDURE Walter D. Tiedeman, Chairman...... Albany, N. Y. DAIRY FARMS METHODS F. D. Holford, Chairman...... New York City SANITARY CONTROL OF ICE CREAM F. W. Fabian, Chairman...... ;...... East Lansing, Mich. LABORATORY METHODS A. H. Robertson, Chairman...... Albany, N. Y. METHODS OF IMPROVING MILK SUPPLIES IN SMALL COMMUNITIES Leslie C. Frank, Chairman...... Washington, D. C. PUBLICITY AND PUBLIC RELATIONS . Sarah Vance Dugan, Chairman...... Louisville, Ky. RESOLUTIONS Ernest Kelly, Chairman..:...... Washington, D. C. LOCAL COMMITTEE ON ARRANGEMENTS FOR THE 1938 MEETING H. O. Way, Chairman. .Cleveland, Ohio JOURNAL of MILK TECHNOLOGY Volume 1 May, 1938 Number 4

Editorial Section The opinions and ideas expressed in papers and editorials..are those of the respective authors. The expressions of the Association are completely recorded in its transactions.

A Pediatrician Talks to Milk Technologists Dr. Irying J. Wolman of the Children’s Hospital of Philadelphia recently ad­ dressed the Metropolitan Dairy Technology Society on the researches that he and Dr. Chambers are conducting on the digestibility of milk, especially of soft curd milk. The milks are tested in bladder-like bags kept at body temperature by immersion in a water bath. A special apparatus gives a kneading action simulating the peristaltic contractions of normal stomachs. Synthetic gastric juice is supplied from burettes. All experimental conditions are kept constant in the various tests. The curds which form are carefully measured in sieves, and the data subjected to mathematical analysis. By this technique the kinds and sizes of curds which form in the human stomach un­ der different conditions can be carefully studied and the various kinds of milk com­ pared with one another, Soft curd milks form smaller curds than does usual market milk, which regularly yields huge cheesy masses. Curd tension readings obtained by the Hill tests do not always run parallel to curd size. Homogenized milk yields large or small curds de­ pending on various factors including the head of pressure used. Base exchange milk under conditions of low acidity does not curdle and remains liquid. However, when the acid is high, as occurs in adults, this milk coagulates and forms large hard masses. Sonic or sound wave treated milk regularly forms small curds. Dr. Wolman pointed out that the improved digestibility of fine curds had been clearly demonstrated by Brennemann over twenty years ago, and reminded us that this significant finding had been ignored by the dairy industry whereas the evaporated milk concerns considered it very important. The large curds from fluid milk account for much of the antipathy towards milk drinking. The medical profession needs a definition of soft curd milk. Is the Hill test a good index? The many factors which enter into milk curdling within the stomach clamor for scientific study. The dairy industry would be farsighted and wise in spon­ soring research on this problem. Improving the digestibility of market milk would stimulate consumption and sales. Editorials

It was pointed out that no cow’s milk is satisfactory for infant feeding until it is modified in the direction of the composition of human milk, namely, fat 3.5 percent, protein 1.5 percent, carbohydrate 7 percent. A large amount of clinical and experi­ mental evidence has shown that the percentage of sugar in cow’s milk must be raised to the breast milk level before infants can thrive upon it. One wonders whether ice cream mix could be converted into a satisfactory infant food, since its ingredients are in approximately the same proportions as are those of human milk. Dr, Wolman asked us many questions about milk which showed that we have much to learn about our own product, as for example, what is the effect of freezing on the digestibility of milk? Why are baby milk formulas diluted? Why is un­ modified cow’s milk unsatisfactory for infant feeding? Why is the carbohydrate- protein ratio of human milk superior in nutritional value to that of cow’s milk ? How does the boiling of formulas eliminate indigestion ? When we think of the large number of laboratories and the hundreds of investi­ gators who have engaged in dairy research, it does seem surprising that there still remains so much that we do not know doryn in those brackets, so to speak, of our every-day use of milk. Moreover, we have witnessed the inroads of evaporated milk into the market for fluid milk. We have seen the household freezing-of ice cream come in great volume. We see soybean milk looming. We behold the doubftul status of filled milk legislation. We see an increasing market for oleo- and nut margarine. The dairy industry can weakly bewail this situation and weep over its lost markets, or it can rise in its might and organize research to open new markets. It has the choice of either course. J. H. S. Butter Score Versus Quality The official method of scoring butter is being superseded by a new rating pro­ cedure. The past practice has prorated the score over various factors, including the type of package. The new method classifies butter at a certain flavor level which car­ ries a score between 85 and 93 with small tolerances for minor defects. From this rating is subtracted the sum of the ratings for defects of body, color, and salt (see page 19 of this Journal). No mention is made of the sanitary quality of the butter. Milk sanitarians know that in the production of milk there are important consid­ erations of cleanliness which never can be measured by even the most refined labora­ tory examination. The public ·themselves insist on certain esthetic and public health provisions in the handling of milk—sound cattle, clean farms and equipment, sani­ tary practices, healthy employees. The same carefulness obtains in the manufacture of ice cream. This is the basis for farm and plant inspection, namely, to see that which no examination of finished product can reveal. The scoring of butter ignores these factors of sanitation—factors which the public demand in milk and ice cream. Therefore, scoring must be considered as merely a commercial expedient for the organoleptic grading of an agricultural commodity (like wheat and apples and cotton). We must not be misled into thinking that the score is anything more than a partial rating of quality. The new scoring procedure seems to be an improvement in reasonableness, sim­ plicity, and accuracy over the former method. In view of the increasing attention that food control officials are giving to the public health relations of butter, it would seem that the score should recognize proper pasteurization and freedom from extraneous material. These need not necessarily appear as factors in the organoleptic score but they might be used to determine whether the butter is first class or second class, the former when the cream had been, properly pasteurized and was clean, and the latter when otherwise. The word "grade” should: not be used because of its application in other connections. J. H. S. Journal of Milk Technology 3

The Need for Official Supervision of Laboratories* Friend Lee Mickle, Sc.D., Director, Bureau of Laboratories, Connecticut State Department of Health This address is not a plea for official dairy laboratories and the licensing of all supervision of laboratories. It should be personnel. plainly self-evident to an assemblage of There are several reasons for unreliable milk sanitarians and food and health of- ■ reports from laboratories. The shyster ficials that a need exists for some of­ who deliberately falsifies his findings for ficial control over laboratories where ex­ the benefit of his client has seemed to be aminations — bacteriological, chemical much more of a rarity than might be ex­ and other—are made of milk, cream, fro­ pected. Far more frequently encountered zen desserts, and milk products just as it is the well-intentioned person who has a exists in other branches of public health lack of adequate training and experience, laboratory activities. The opportunity will but who considers himself or herself ca­ be used to present in the light of experi­ pable of making and reporting to the ence and observation some reasons for public examinations of milk or dairy believing that supervision of local lab­ products. Too often, the college gradu­ oratories is necesary and to discuss briefly ate with very little training in bacteriology procedures and standards that have proved and chemistry, and sometimes with no ex­ feasible for improving the quality of work perience, carries on laboratory work or in laboratories already under supervision. makes interpretations of results that may This cannot be done without making evi­ give false impressions of the quality of dent the need for official supervision. the supplies under examination. Failure Without general oversight from some to use proper apparatus and the improper official contrbl agency, there is no ques­ use of equipment are frequent causes of tion that at times results will come from unreliable results. The overcrowding of certain laboratories that will not only incubators with plated samples and the cause real annoyance to city and state of­ use of incubators so constructed or so ficials but, far more important, will bring small that reliable findings could not by to the milk producer and milk dealer, defi­ any possibility be expected are examples nite losses of money and business. Where of instances where conditions may be im­ is the milk control official who has not proved by supervision and inspection. experienced embarrassment in attempting to explain conflicting plate count find­ Let it be said at once that official sup­ ings on similar samples examined in dif­ ervision is not per se a panacea for all ferent laboratories! It is an illuminating the ills oil unsatisfactory laboratories. It comment that in one state the annoyances must be constantly borne in mind that caused to the milk industry by the an­ the best trained laboratory expert, wheth­ alyses and interpretations from unsuper­ er supervised or not or even when acting vised laboratories—private and pub­ as supervisor, has to be constantly on lic—became so serious that the milk in­ guard against the many pitfalls that beset dustry itself, independent of the state him who tries to do a perfect job of control agencies, sponsored the passage of analyzing a sample of milk, dairy pro­ legislation that now requires approval of duct, or frozen dessert. Most of those who produce inaccurate and misleading * Read before the Twenty-sixth Annual Meeting findings are honest persons trying to the of the International Association of Milk Sanitarians best of their ability and training to do a and the Conference of Ohio Valley Food, Drug and Health Officials, Louisville, Ky., October 13» 1937, good job. No one can do a perfect job 4 Official Supervision of Laboratories all of the time. To bring about improve­ making or interpreting the results of ment under conditions such as these, sup­ some other determination. For example, ervision must go hand in hand with co­ many well-trained chemists may not have operation. The official who would be the background of training to make and successful must bring to his task an in­ interpret properly rather simple bacteri­ terest in his work and a spirit of co­ ological tests. Limited approval for spe­ operation toward those with whom he cite lines of work is more generally in works. Regardless of the authority he vogue than is unqualified approval. represents, he must be friend, fellow , worker, teacher, and diplomat to a far LAWS AND REGULATIONS greater extent than he is inspector. Auth­ Prerequisites for official control of, ority and inspection by themselves will laboratory work in whatever field are never produce the desired results. law and regulations. A law may be either It is not so much that a supervising simple or involved. An example of the agency will be enabled to improve the former is a statute requiring merely that quality of work in local laboratories by any laboratory making specified examina- some magic show of policing authority. tiqns be registered with or approved by Rather will results be accomplished by the official control agency—usually the restraint in the use of a potential power state department of health. Registration held in reserve for the very occasional in­ without approval is not to 'be recom­ stance where coercion must replace co­ mended. A more involved law might operative and educational effort. Yet the specify in detail the methods and pro­ power to revoke approval that has been cedures to be followed, the requirements extended gives to a state or provincial de­ for housing, equipment, and apparatus, partment of health the opportunity to an^l the qualifications of the personnel make thorough investigation in the infre­ or of the person in charge. Under most quent instance when it is necessary and circumstances it is desirable to have the at the same time equips that department laty as simple and brief as is consistent with a handy correctional weapon. with rather broad powers, and preferably Through the agency of approval and in to have it provide full authority for the a manner not at all magical, there is approving agency to promulgate rules, a tendency for the quality of the work requirements, and standards on which to improve in both the good and the approval shall be based. The power of mediocre laboratory while the bad labora­ revocation of approval for cause should tory may pass out of existence. be specified. Requirements now in effect throughout the country are in some in­ GENERAL OR SPECIFIC APPROVAL stances in the form of sanitary code Blanket laboratory approval may be regulations; in others, merely depart­ given to a laboratory after inspection of mental rules. It is desirable that all types the equipment and investigation of the of laboratories be covered including those qualifications of the personnel or of the in city departments of health, in educa­ person in charge. On the other hand, it is tional institutions, in hospitals, in milk entirely feasible to require that the per­ plants, and in those laboratories operated son operating a laboratory apply for ap­ commercially or privately for profit. proval for a specific list of tests and to The limiting of approval to those tests insist that the results of no other exam­ where the results are "used” or "pub­ inations be used or published until ap­ lished” has been found to have advan­ proval has been extended to cover those tages. Under a law which embodies that tests: Blanket approval is beset with provision, a laboratory operated by a milk difficulties for the reason that the person plant only for the examination of both in charge of a laboratory may be capable process and bottled samples of the firm’s of making certain varieties of examina­ own product and of samples from cans tions or tests and yet be incapable of of producers’ milk would be exempt Journal of Milk T echnology 5 from approval. Thus the law would not used. Where there are available stan­ intrude into the private business of an dard methods , that are sponsored by some individual, a firm, or a corporation. The national association, as in the case of laboratory technician at a milk plant milk and dairy products, it is feasible and might even become interested in testing usually .desirable to require the equip­ the products of competitors and could ment necessary to carry out the standard legally do so under this type of law with­ method in question, especially since in out applying for approval unless the re­ many instances certain pieces of equip­ sults were published or some of them ment are described in the printed method "used” by salesmen or in some other way or are given in specifications. that the sales or interests of competitors Inspection should be provided.to de­ might be affected or unless the products termine at reasonable intervals that the of the firm were advertised on the basis several kinds of apparatus in use are kept of the findings obtained. Should the re­ adequate for any increasing volume or sults be used in such ways, it is evident changing lines of work, and that all that the requirement of approval should equipment is kept clean and in good con­ appjy. dition. It should be possible to insist HOUSING AND QUARTERS that pipettes with broken tips be prompt­ It is rather universally considered that ly discarded and that only pipettes of adequate housing for the laboratory shall given specifications be used. It is sur­ be made a prerequisite for approval. prising how greatly the discrepancies be­ There is room for a wide range of opin­ tween plate counts or milk-fat tests among ions but it must be realized that reason­ different laboratories can be reduced by ably reliable examinations even of a bac­ enforcing such simple provisions. It is teriological character can be carried on equally surprising how far afield in these in fairly crude quarters if the rooms are matters well-trained laboratory technicians decently clean. For that reason standards ■—and for that matter even directors of for housing should not be set too high. laboratories—will allow themselves to go Yet in this day and age, it is certainly where there is no supervision. In labora­ not going too far to require clean, com­ tories where the volume of plate count fortable, fairly commodious, and well- examinations varies from day to day, the lighted working quarters without involv­ inspector should be prepared to look for ing undue expense. Regulations should overcrowding of incubators. Owners of be sufficiently flexible to allow the com­ laboratories are far too prone to purchase mon sense and good judgment of the ap­ incubators that are much too small or too proving official a reasonably wide range cheaply made. There is an all too general of play. laxity that permits operating incubators at varying temperatures, often falling out­ EQUIPMENT AND SUPPLIES side of the allowable range unless there is In a system for the control of labora­ supervision and the laboratory personnel tories provision should be made for re­ is advised of and educated to a proper quiring the use of standard equipment. understanding of the serious and trouble­ It may be sufficient merely to require some errors that result. Regardless of that apparatus be on hand, complete, and opinions as to the value of the standard in good order at all times for making plate count or any other laboratory test, each determination, examination, or an­ a test had better be left undone than to alysis, according to the methods which be poorly or indifferently made because the person in charge has agreed to fol­ of poor equipment or for some other low and has been authorized to use. Such reason. Inspection should be so designed a requirement allows the control official and carried out as to eliminate bad ap­ enough leeway to meet special situations paratus and promote the use of good and yet gives him the necessary authority standard equipment, supplies, and re­ for insisting that standard supplies be agents. 6 . O fficial Supervision of Laboratories

METHODS AND PROCEDURES before receiving a license to make certain The value of the work done in a lab­ more complicated determinations or to oratory usually is more a function of the take charge of a laboratory. In another method or procedures followed and of the part of the country, any applicant who can accuracy and intelligence with which they pass a written examination and demon­ are adhered to than it is a function of strate his ability to perform a butter-fat the housing and the equipment. Before test, an official plate count, or some other approval is extended it is desirable that determination is given a "limited” license there be definite agreement on the part (empowering that person to perform that of the person in charge of a laboratory fest or tests, working as an assistant in that any determination, examination, or a laboratory. Yet to take charge of a analysis of a milk, cream, frozen des­ laboratory where not only are such tests sert, or dairy or other product will be made but the results interpreted to per­ made strictly in accordance with a speci­ sons outside of the laboratory, the person fied procedure. This may be either the must hold a "full” or unrestricted li­ latest edition of the Standard Methods cense which is issued only to a person of Milk Analysis of the American Pub­ yffio, before taking the examination, has lic Health Association, the Methods of obtained a bachelor’s degree from a col­ Analysis of the Association of Official Ag­ lege or university and has passed a course ricultural Chemists, the Methods of an­ of instruction in the test or tests cov­ other similar organization, or the latest edi­ ered in the license. The obtaining of an tion of any method approved by the sup­ unrestricted license is made the first step ervising agency, in each case using the toward securing approval of the labora­ equipment specified in the method fol­ tory. lowed or in any written modification with which the person may have been supplied. responsibility o f t h e h e a d o f t h e Since standard methods, national or in­ LABORATORY ternational in scope, may not always be When approval is extended to a lab­ applicable to local situations or quickly oratory, some person—usually the one in amendable to changed conditions, it is charge—should be made strictly account­ a wise precaution to provide authority able for the reliability of. the work done for demanding adherence to methods and and for the accuracy of the interpreta­ procedures drafted by the regulating auth­ tions of findings issued from the labora­ ority and capable of being modified from tory. Experience has indicated that re­ time to time when need arises. quiring the signature before a notary of LICENSING OF PERSONNEL the person concerned brings home the seriousness of the approval agreement in In some states, the licensing, of per­ an effective way. sonnel is considered a sufficient safeguard against laboratory work of poor quality The person in whose name the labora­ without any other requirements; in other tory is approved may be required to places, licensing of personnel is merely agree that: a prerequisite for approval of the labora­ 1. The conduct of the laboratory will tory. It is customary to require the ap­ be strictly in accordance with recognized plicant for a license either to pass an ex­ standards of laboratory ethics and that amination or to submit credentials from no method or procedure will be followed an accredited institution of learning to that fails to meet the requirements of the the effect that certain courses in dairy approving authority. bacteriology or chemistry have been com­ 2. Any determination, examination, or pleted with satisfactory passing grades. analysis will be made strictly in accord­ In one state, a person passing an ex­ ance with specified methods as already amination to do the simpler tests must discussed under the heading "Methods later take a second, or even a third, test and Procedures.” Journal of Milk T echnology 7

3. The person in charge will notify and up-to-the-minute procedure that the approving authority immediately when should have been readily available to him changes in technique or personnel are or because he has used poor equipment, made or are about to be made. supplies, or reagents that have rendered 4. The person in charge will be re­ the findings unreliable. Once in a while sponsible for the accuracy and reliability an experienced person in charge of a of the laboratory findings made by any busy laboratory may base an interpreta­ person or persons employed in the lab­ tion on unreliable findings or on tests oratory, and for any interpretation based made by an unqualified or careless person. upon those findings. Any examinations, de­ If the person in charge of a laboratory terminations, or tests will be actually is legally required to obtain a certificate carried on by a person or persons hold­ of approval before reporting any test ing either a full or a restricted license where the results will be used or pub­ from the licensing authority. lished, this step will go far toward im­ 5. Copies of all reports issued from proving the quality of work of the labora­ the laboratory will be kept as permanent tory, providing a well organized system records in the files of the laboratory of approval and inspection gives oppor­ available at any time to representatives of tunity for education and cooperation the approving authority. along with the regulatory aspects. If the laboratory director has agreed under oath 6. If at any time the person in charge to surround the work with a variety of is engaged on a part-time basis, that safeguards, he is likely to supervise with person will inform the approving auth­ care all the steps of each analysis and to ority of the approximate amount of time weigh well the conclusions based on the given to this position. laboratory findings. Requirements for 7. In the event the person in charge adequate housing and standard equip­ severs connection with the laboratory, or ment, apparatus, and reagents are desir­ is about to sever it, that person will able, but even more important is provision immediately notify the approving auth­ for determining the qualifications of per- ority in writing and return to him the sonel—particularly of the person in certificate of approval. charge—either by examination or through investigation of credentials before ap­ SUMMARY proval is extended. It is important that At times, there are issued from labora­ the person in whose name approval is tories the results of findings that are in­ extended be required to sign an agree­ accurate and interpretations of laboratory ment with the certifying agency that tests that may range from those which specified standards for high grade work are merely misleading to others that on will be consistently maintained. occasion may have a serious effect on Experience with a system of approval the profits or the reputation of a milk has shown that closer coordination of re­ dealer or producer. Erroneous or fallaci­ sults between laboratories has been se­ ous laboratory reports and conclusions cured and that there is less complaint than tend to lower the confidence of the pub­ formerly from persons whose products lic in the worth of laboratory testing in are under test. Under a system of approv­ general. Very occasionally, unreliable re­ al, there is added incentive for persons ports are the outcome of dishonest at­ operating laboratories to man them with tempts to mislead. Far more often they qualified personnel and for technicians to result from careless or thoughtless errors demand proper equipment and supplies on the part of well-meaning persons im­ with which to work. While it is seldom properly qualified and experienced to necessary to exercise the vested authority, make and interpret particular tests. Per­ the machinery is set up for preventing haps they frequently occur because the the bungler or the novice from issuing analyst has failed to follow an improved laboratory reports, for supervising the shy­ 8 A Colorimeter For the Phosphatase T est ster laboratory almost before it comes been extended. It would seem that no into existence, and for improving the laboratory should be the worse for being quality of work in the laboratory where under a properly conducted approval sys­ the training or experience of the person­ tem and certainly the poor laboratory nel is barely adequate for carrying on the should be improved or show reason why variety of tests for which approval has it should continue to exist.

A Colorimeter For the? Phosphatase Test W. H. Boynton and P. E. Nelbach, Department of Public Health, Yale University School of Medicine, New Haven, Conn. In view of the rapidly increasing use slightly different colors was made some­ of the phosphatase test for determining what easier by using a blue glass plate the degree of pasteuri2ation of milk, a as a background against which to read suitable method of reading the results the tests. With this information in mind, of the test has become important. a colorimeter was designed and built, The results of the original tests per­ consisting essentially of a light-proof box formed by Kay and Graham1 were read by containing a daylight bulb and a blue comparing the depth of blue color pro­ glass plate with a sliding rack for samples duced in the tests with blue glass stan­ and standards fitted into a viewing chute. dards in a tintometer. Gilcreas and Davis2 An opaque turquoise blue vitrolite glass have found that a comparison of the char­ tile4, size 8x12 inches, forms the bottom acteristic color reaction of the phenol of the colorimeter. To obtain an "egg­ liberated in the test, with known phenol shell” surface for diffuse reflection, the standards provides a more convenient and glazed surface of the tile was etched with accurate determination of degree of treat­ hydrofluosilicic acid, ment than the measurement of the color A light-proof box with viewing chute in a tintometer; but since phenol stan­ at; a 45° angle was built to fit over the dards deteriorate even when stored in an glass tile. (See diagram). The light ice box and protected from light, they source is a 100-watt daylight bulb cen­ used stable inorganic solutions in a series tered in the top of the box so that no of permanent standards corresponding to direct illumination can penetrate the view­ :he phenol standards. ing chute. The inside of the top was These permanent standards were devel­ finished with aluminum paint to act as a oped for use with natural daylight, a diffuse reflector, and the remainder of the variable quantity, and under any but box was painted matte black. Ventila­ optimum conditions the blue color of the tion holes were bored in the back and standards has a reddish tinge which is sides of the box to remove the heat of not present in the samples. A sample the bulb. may be matched readily with the standards In the upper end of the viewing chute, by using, as a background, a cloudless a slot was cut for the rack containing the blue sky without glare, but when these inorganic standards and the sample to ideal conditions are lacking, the difference be read. This sliding rack was built to in the color quality, of the standards and hold 6 x y8 inch test tubes (requiring 10 samples makes matching difficult. Gil­ cc. samples), and the standards were ar­ creas and Davis3 later found that the com­ ranged in alternate holes in order of in­ parison. of the intensities of the two creasing depth of color. A light baffle Journal of Milk T echnology 9 placed in the chute directly 'behind the the sample, making possible a reading rack makes only three spaces visible at a based on depth of color alone. Avoid­ time, the sample occupying the middle ance of direct illumination and outside space with a standard tube on each side. light make the comparison relatively Light rays from the daylight bulb and simple. The light chute set at an angle reflected from the aluminum painted top and the rack containing the complete set strike the blue plate perpendicularly and of standards add to the convenience of can pass up the viewing chute only by use. diffuse reflection. The longer (red) wave This colorimeter, used in studies of lengths given off by the daylight bulb the phosphatase test,* has been found to will be absorbed to a large degree by the blue tile. The elimination of direct re­ give constant readings. Different observ­ flection from the tile plate assures that the ers can obtain the same readings with light reaching the observer’s eye will be the same samples at any time of day or of a color quality which will minimize the night, and .under varying weather condi­ color difference between the standards and tions.

Colorimeter for th e Phosphatase Test

Spaci fi cations Box made of '/4 plywood, corners cleated w ith '/{ quarter round stock. Guide strip on rack J^'V/V Center brace @ -

Aided by a grant from the Fluid Research Fund of the Yale University School of Medicine. REFERENCES 1. H. D. Kay and W. R. Graham, Jr.— 3. F. W. Gilcreas and W. S. Davis—"The "The Phosphatase Test for Pasteurized Practical Value of the Phosphatase. Test Milk.” Journal of Dairy Research, Vol. in Determining the Efficiency of Pas­ 6, pp. 191-203, (1935). teurization.” Laboratory Section—Pro­ 2. F W. Gilcreas and W. S. Davis—"In­ ceedings of the Thirtieth Annual Con­ vestigation of the Amylase and Phos­ vention of the International Association phatase Tests as an Indication of Pas­ of Milk Dealers. teurization.” Twenty-fifth Annual Re­ 4. Tile manufactured by the Vitrolite Com­ port of the International Association of pany of 570 Lexington Avenue, New Milk Sanitarians, pp. 15-39, (1936). York City. 10

The Problem of Recontamination of Pasteurized Milk and Its Products* L. C. Bulmer Director, Bureau of Food and Dairy Inspection, Jefferson County Board of Health, Birmingham i, Alabama One of the great handicaps toward century, and has been accepted as an im- progress in the final solution of the city portant public health safeguard for more milk problem is the fact that we hear than thirty years, the fact still remains too much ballyhoo about the magic of that a great volume of pasteurized milk pasteurization. A stage has long been sqld under present market conditions is reached, where we are in need of more actually little or no safer than raw milk. enlightenment as to the dangers of pos­ In Birmingham, we are persuaded that sible recontamination of pasteurized dairy in the official control of miik and its products under roufine commercial con­ products, there are certain paramount ditions. fundamentals to be attended to, and that It should be clear to everyone that if the less we confuse these in petty detail, pasteurization of milk and its products is the better off we shall be. We have a a necessity of safety—and all recognized code which we believe to be practical, and authorities agree that it is—then it is while it embraces certain detail which- equally as important to go the limit in may confound a lawyer who aims to con­ protecting sucn products, once pasteur­ test its validity in court, we have, never­ ized, against recontamination, for other­ theless avoided the inclusion of all su­ wise, the whole purpose of pasteurization perfluous detail apt to confuse ourselves. has been defeated. Public officials and In keeping with this discussion, the commercial interests who do not fully question naturally presents itself as to recognize this fact are living in a fool’s what ate the fundamentals as we see them paradise. In fact, they are sitting on a in Birmingham? We believe that pas­ powder keg which may explode and ut­ teurization of milk products adequately terly destroy public confidence in pas­ controlled is only part of the answer to teurization for a period of years. the city milk problem. In addition, we The problem of adequately safeguard­ go further than this and contend that the ing pasteurized dairy products against re­ final solution of the problem depends contamination is one that has received equally as much upon subsequent rigid scant, if indeed, any, worthwhile atten­ supervision and control after pasteuriza­ tion either in this country or abroad. This tion against possible routine recontamina­ fact bespeaks a lack of appreciation of tion. one of Pasteur’s greatest contributions, not About ten years ago, Dr. J. D. Dow­ only to the health protection of the hu­ ling, Health Officer of Birmingham, blaz­ man race but also to the stability of ed the trail in this country when he fos­ the dairy industry. tered and persuaded the City Commis­ It is a rather shocking confession to sion to adopt regulations that required have to make that while the process of all milk, cream, and ice cream mix to pasteurization has been in vogue as a flow directly from the pasteurizer into the commercial expediency for almost half a final container. It is worthy of note that the validity of this provision was recent­ * Read at the Dairy Short Course, ( Dairy Depart­ ly reviewed by the Alabama Supreme ment, University of Tennessee, Knoxville, Tennessee, Thursday, February 10th, 1938. Court and upheld. Journal of Milk T echnology 'l l

It is obvious that such a provision in from the pasteurizer to the final container official control of milk and its products excepting Birmingham, and while a num­ is of major importance in the matter of ber of cities claim to require bottle milk safeguarding against recontamination of service of milk in restaurants, review of a product after pasteurization. To clari­ the ordinances of most of such cities who fy this point in respect to milk and claim such provision reveal that the re­ cream, the final container is legally con­ quirement is more or less arbitrary rather strued as the bottle itself, while in regard than one of definite legal provision in the to ice cream mix, it is construed as the milk code. It is gratifying to observe, freezer which automatically prohibits pro­ however, that thirteen major cities thus miscuous freezing or rehandling of ice far have adopted regulations requiring cream mix in soda fountains, restaurants, caps that adequately protect the lips of or, in fact, any place outside the ice cream the bottles. plant where the mix is manufactured. We may pause here a moment to ob­ What are the actual conditions in the serve that those persons with field inspec­ average American city today in regard to tion experience will appreciate the fact the rehandling and possible recofitamina- that where bulk milk is permitted to be tion of pasteurized mil'k and its products? handled in a restaurant, it will be served With a view to determining this fact, I more frequently than not, as dip milk in recently addressed a questionnaire! to the a glass, and that it would take a squad lorty-one major cities of the United States of inspectors as large as a regiment of of more than 200,000 population, and soldiers to prohibit such practice, no mat­ I am indebted for what I consider to be ter whether the bulk milk be grade A, an excellent response insofar as question­ B, C, or labeled Grade D Raw Milk naires go. "for cooking purposes only” as it is so Thirty-four replies were received! out labeled in the Standard Milk Ordinance. of the forty-one requests. In addition, Insofar as the so-called United States our files carry copies of the milk or­ Standard Milk Ordinance is concerned, it dinances of the few cities which failed \to is inadequate in so many ways that it is respond, thus providing an extremely difficult to briefly summarize its short­ clear picture of the present situatioq. comings without going beyond the scope Based on the response to the question!· of the subject under discussion. Briefly, naires, sixteen of the cities require the however, while it goes into a maze of bottling of mi'lk on the same premises', minute detail as to how milk shall be where pasteurized, but not a single one \ pasteurized and the niceties of the equip­ prohibits the sale of bulk pasteurized ment used, the provisions of safeguard­ milk in cans to restaurants, soda foun­ ing the product after pasteurization are tains, and similar eating establishments. either entirely overlooked or are omitted. Twelve of the cities have compulsory pas­ To exemplify, it has no provision teurization ordinances, but this is not all which prohibits repasteurization of milk, that it may seem since up to 20 percent or while it sanctions milk pumps in res­ more of the entire milk supply in such taurants and soda fountains under pro­ cities is distributed in bulk. Repasteuriza­ visions of petty detail for the service of tion of the product is allowed, or at least bothV raw and pasteurized milk. Those not prohibited, in thirteen of the cities, with practical experience with such milk while eighteen do not requite the dating pumps will appreciate the sanitary signi­ of milk. Twenty-two of the cities per­ ficance, of this fact. mit bulk milk for service in hospitals, In fact, nothing in the ordinance pro­ four in school lunch-rooms, while sev­ hibits the juggling of pasteurized milk or eral cities were indefinite in their replies ice cream mix after processing at on this subject. the plant, restaurant, soda fountain or Not a single city in America requires elsewhere.'^ It not only affords but rather compulsory flow of the product direct extends itself toward multiplicity of 12 Recontamination of Pasteurized Milk Products grades, and there is nothing that prohib­ 2. The question of promiscuous re­ its a restaurant keeper, for example, hav­ handling of ice cream mix in soda foun­ ing grades A, B, and C of both raw and tains -and other places of business where pasteurized milk simultaneously in his it is frequently subject to careless prac­ possession in promiscuous bulk form. In­ tices, slipshod methods, and often held deed, a restaurant keeper may serve grade for prolonged periods of time, even days, D taw milk, delivered in cans and labeled at too high temperature before the pro­ "for cooking purposes only”, simply by duct is eventually frozen. This also may pouring it into a glass and presenting it be corrected by requiring not only that to some poor deluded patron who will such mix shall be pasteurized on the same consume it, provided, of course, that the premises where frozen but also that mix eagle eye of some inspector overburdened shall flow directly from the pasteurizer with petty detail, happens not to be peer­ into the freezer. In addition to the obvi­ ing through the window at the time. ous advantages of this provision, it also Insofar as the -questionnaires showed, it controls careless rehandling of the pro­ is of interest to note that only ten of the duct at the point of manufacture, namely, major cities in America have adopted the in the plant itself. said Standard Milk Ordinance or some 3. The question of covering the lips modification of it. On the other hand, of the bottles with an appropriate hooded about five hundred or more smaller mu­ cap that not only affords sanitary pro­ nicipalities have adopted it. There is no tection but also cannot be removed or doubt that regardless of its faults, and tampered with without the possibility of there are few if any milk ordinances the fact being clearly revealed to the con­ which have none, the Standard Milk Or­ sumer. This is to be regarded as a much dinance may serve a useful purpose in neglected factor in the protection of pas­ certain rural communities which are con­ teurized milk against recontamination. fronted with more or less primitive con­ All such- fundamental milk control re­ ditions. However, we, in Birmingham, quisites as these are based upon practical have never seen the wisdom of experi­ necessity rather than theory. They afford menting with it in an effort to make its enough, talking points that-with the prop­ provisions practical of enforcement in a er approach by public health officials, pas­ large city milk shed. On the other hand, teurization interests of most every city the few large cities of this country which could be prevailed upon to endorse them have adopted the Standard Milk Or­ as a cold-blooded business proposition dinance have mostly modified it to a de­ without unduly involving a controversy in gree almost beyond recognition by way of Iqcal politics. laying greater emphasis on fundamentals and omitting provisions which have /no We have never found it such a difficult public health basis on which to stand. matter to make a friendly approach to industry and obtain its wholehearted co­ To return to the subject and sum­ operation in matters that can be shown to marize some of the major problems; inci­ have some practical virtue of progress. On dental to the recontamination , of pasteur­ the other hand, I am sure that the majori­ ized dairy products, particularly; milk, ty of us realize that industry bemoans and cream, and ice cream mix, there is: quickly becomes resentful of governmen­ 1. The question of tehandlingof pas­tal agencies who are inclined to egotis­ teurized milk and cream in bulk form tically place full responsibility upon its after progessing. This applies to/the plant shoulders for all the ills that attend the itself as much as to elsewhere. This present day milk business. The action of may be and should be corrected by re­ such officials is to be deplored since it quiring flow, of the product from the pas­ often impedes and sometimes totally ar­ teurizer into the final container which is rests over long periods of time, initia­ the bottle itself. tive and ingenuity of industry.

/ Journal of Milk T echnology 13

After all, industry has done its full The problem involved js becoming con­ share in the past, indirectly at least, to­ stantly more complex because we are be­ ward solving many of the modern day fogging the w ide question in this coun­ sanitary milk problems. try by adopting milk ordinances which Contemplation will reveal many ex­ are overflowing with trivial detail that amples where zealous measures of pub­ cannot possibly influence the mortality lic health today are merely the aftermath rate one iota; and, at the same time, are of research in the .interest of commercial omitting consideration of the most vital expediency of the dairy industry in one fundamentali. way or another. Pasteur, for example, in Many years ago, Hastings of Toronto, 1864, introduced pasteurization to safe­ truly said that there are but two grades guard against the "diseases of wine”. ■ of milk wi|h which a board of health can Denmark, about thirty years later, ap­ concern itjel-f, "safe” and "dangerous” plied it to safeguard against "olf flavor” milk. Yet? today, if we look around over of butter and the spread of tuberculosis the county, we find that milk ordinances among hogs through skim milk. Another are sponsored and frequently adopted by quarter of a century elapsed before it certain boards of health, recognizing and dawned upon boards of health, led by indeed dignifying multiplicity of grades Chicago and Toronto, that pasteurization to the estent that A, B, C grades of pas- could be utilized as a safeguard of the teurizedimilk and A, B, C, and D grades public health. of rawjmilk are officially approved. In Similarly, the m ilk bottle was first in­ other vjords, instead of an effort being troduced to expedite, retail distribution made to concentrate entirely upon abso­ of milk and for advertising the cream lute mjhimum requirements of safety as, . line. Many public health officials at the for example, in the case of water supplies, outset gravely frowned upon this depar­ there are those who would condone and ture from dip milk. Furthermore Koch’s officially dignify every grade of rotten research in bovine tuberculosis in the late milk imaginable in alphabetical order on nineties was largely a commercial endeav­ or to eradicate a great economic plague the erroneous and pitiful assumption that among cattle, while we may all recall the the great public at large knows its milk commercial origin of the old cremometer, alphabet. the lactometer, and the Babcock test. Insofar as the subject discussed is con­ The important part played by industry cerned, there are but two amazing con­ as a leader in the solution of many sani­ clusions to reach: In the first place, we as tary problems illustrates that probably public health officials, are causing Ameri­ some o f us as governmental officials are can industry to expend thousands of dol­ apt to take ourselves too seriously and lars ahnually to perfect the niceties and take more credit to ourselves than we various gadgets of pasteurization machin­ really deserve at the expense of industry. ery, ohly -to permit the product so scien­ With more careful and rigid official tifically pasteurized to be subsequently supervision but with much less unneces­ sary petty interference, industry as in the kicked^around like a fo°tt>all in the mud; past is more likely than not to outstep Andj in the second place, from the government in the final solution of many public health side of the matter, w e are in of our peculiar milk and general food the ludicrous position of "straining a- problems as we know them today. . gnat and swallowing a camel.” 14

Practical Farm Sterilization* A rthui H. Williamson, B. S., D. V. M. State Dairy Supervisor, Florida Estate Board of Health . Jacksonville, Florida

From a public health viewpoint it does thing to keep it sterile. Poor storage not matter how sterilization is accom­ aftep sterilization can and often does nul­ plished. H ot water; chemicals, Steam, dry lify the process. air, .or a combination of any or all are The next factor in recontamination of equally effective, if properly carried out. dairy equipment is It is the haphazard way in which farm sterilization is attempted that constitutes WATER OF CONDENSATION the weakness of most of the programs Linder most of the 'sterilizing processes which have been observed. In the deep nary in general use, there is left adhering south, there is a redundance of small raw to the cleaned and sterilized equipment milk producer-distributors. The hazard this condensed moisture. Moisture is con­ of such a situation is well recognized. It ducive to the development of bacteria. is one of the big reasons why we especial­ The presence of ■ this water would not ly should insist on proper sterilization and havip great significance if the equipment, storage o f dairy equipment and see that after bactericidal treatment, were bacteri- the dairynien have adequate facilities for ologically sterile. accomplishing it. The human element is This is not the case, however. Prac: the big factor in any milk, program, and tical farm sterilization is a "far cry” from it is with this fact in mind that we dis­ absolute sterilization, and fhermophiles cuss the subject of farm sterilization. and other bacteria which are probably at­ A practical process should have many tempted but not killed take’on new life virtues. First of all, it should be efficient; undpr moist conditions and the result is it should entail as little labor as possible; fe-cpntaminated equipment. Especially is and it should not be prohibitive as to cost this true in Florida where the year-round even to the relatively small producer.; temperature is relatively high and where If the process is laborious, the average it is a practice of the dairymen to leave dairy employee will "cut the corners,” their equipment in the sterilizing cabinet so to speak. He is prone to follow the whiph is left closed until the next milk­ line of "least resistance.” If he should ing period. If, on the other hand, the follow the easy way, the result is ineffi­ equipment is taken from the cabinet and cient sterilization and a loss of time and storpd on racks before open windows or money to the dairy owner, to say nothing in any other place where flies, roaches, of the health hazard attendant upon/such or other insects have access to it, the re­ practice. If, on the other hand, the sys­ sult is quite the same— recontaminated tem makes the easiest way the best, way, equipment. we can then be fairly confident that we Any sterilizing process which leaves shall get proper sterilization day by day moisture of condensation on sterilized throughout the entire milk shed. equipment has still another and greater- There is another /fact that should be disadvantage from the dairyman’s view­ borne in mind. It is one thing to proper­ point at least, and that is the deteriora­ ly sterilize equipment and quite another tion o f dairy equipment caused by rust. Hundreds of thousands of dollars are lost * Read at the 26th Annual Meeting of the Inter­ each year by the industry on this account. national Association of Milk Sanitarians, Louisville Kentucky, October 11-13, 1937. Therefore, when we devise sterilizing ap- Journal of Milk T echnology 15 paratus for use by the dairy farmer, we matter, into the rinse water, if only two have several matters to consider— efficien­ compartments are used. cy, initial cost, cost of operation, dura­ It follows then that unless extra pre­ bility, convenience, storage, and ventila­ cautions are taken, the first utensils put tion. through the rinse are sterilized, while Just how, then, can we approach the those following may be actually contam­ ideal in a practical way? The ultimate inated. By employing a vat with the ex­ answer will be dry air sterilization. tra compartment, a very large part of the At present, this treatment has not been organic matter is rinsed off in the second developed to where it can be put to gen­ compartment and never reaches the third eral use. When it has been developed, it compartment containing the chlorine. will revolutionize dairy sterilization in This insures, to a large extent, the chlor­ this and other countries. There is a cry­ ine content of the rinse remaining suf­ ing need for it. Its development is inevit­ ficiently hig;h throughout the process to able. accomplish its purpose. STERILIZATION This has been recommended for years. Of the sterilizing systems which are It is one recommendation that we can in general use today, a chemical and two- well afford to heed. door steam chest combination is es­ pecially adaptable to the retail raw milk STEAM CHESTS producer-distributors, and to the farm .Now we come to a discussion of the pasteurized distributors. It has proved, by steam sterilizing cabinet, its location, con­ far, the most satisfactory (in our experi­ struction, and operation. The most con­ ence, at least) and is gaining the favor of venient place for the sterilizer is between the industry. We like it especially be­ the milk room and wash room— one door cause it is a double-check against a "slip” opening into the wash room and as con­ at the farm. The dairymen like it because venient to the wash vat as possible; the of its simplicity, efficiency, economy, and other opening into the milk room and as convenience. convenient to the cooler. and filler as Of course, either the chemical or steam possible. process, used independently, would suffice, Steam chest sterilization is relatively if properly used, but here again we run new. In our early experiences we wrote into that big factor the "human element.” everywhere for information regarding cab­ If for instance, the chlorine content of inet construction. When we received the the rinse water became so low as to be requested information, it was usually non-effective, you still have the steam on someone’s opinion· not backed by experi­ which to rely. If on the other hand, due ment or experience. We tried their sug-. to negligence of a dairy employee, or gestions, however, and failed. We tried for any other reason, sufficient steam is our own ideas and failed. Eighty-nine not introduced into the cabinet to accom­ cabinets were constructed under our sup­ plish sterilization, the chlorine in the ervision at that time and of the eighty- rinse, in all probability, is there in suffi­ nine, not one was satisfactory. The doors cient quantity to do the job. would buck, sag, and stick—a crow bar I am not going to discuss chemical was standard equipment with which to sterilization at this time, except to say pry them open. The worse part of the this—if we are going to depend on whole situation was that we had to live chlorine alone for sterilization, we should with those monstrosities until they de­ by all means employ the three-compart­ teriorated. We could not very well con­ ment wash and rinse vat. We know that demn equipment that had just been built organic matter dissipates chlorine very according to our instructions, and we cer­ rapidly. During the cleaning process there tainly did not. For two years and more is a large "carry-over” of the wash water, we awaited the decaying process and lis­ which inevitably contains a lot of organic tened patiently to the vigorous protests of 16 Practical Farm Sterilization eighty-nine farmers against a system M ATERIALS Of CONSTRUCTION which required the use of such musty, ill We were told that concrete sterilizers smelling, inconvenient equipment. wqre inefficient and should not be used The consensus of opinion at that time except in instances where large heating was that steam cabinet construction should units were available. W e now know that follow closely refrigerator construction. concrete construction is probably the best We now know this is not the case. we have, and by painting the inside of a Radiation in refrigeration takes place concrete cabinet with Valdura aluminum twenty-four hours a day, every day in asphalt paint, it can be made practically the year—while radiation in steriliza­ as pfficient as a wooden cabinet. W e know tion occurs for only a very short period now that the inside wall of a concrete cab­ each day. inet should not be plastered, because the USE OF STEAM constant expansion and contraction of the wall will cause the plastering to work We were told that steam should be loo,se and fall off. W e simply pull the directed through a small pipe and released insjde form while the wall is green and in the bottom of the cabinet through polish it with a brick, let it dry, and small holes drilled in the pipe at regular paint it with aluminum paint. intervals to insure even distribution of heat. CONDENSATION ” We thought it proper to keep the boil­ What little we know, we have learned er fired and constantly generating steam by the expensive and laborious "trial and to keep pouring in on the mtensils in­ error” method—ajl at the expense of side the cabinet We know now that this the unfortunate dairyman. By this meth­ is erroneous. Steam flowing at atmos­ od, we have learned that wooden cabinets, pheric pressure is at a temperature of with dead air space within the walls, 212° F., steiam at 30 pounds pressure is at would deteriorate in twenty-four months 250° F., steam at 80 pounds pressure is — the strange fact being that the outside at 312° F., and steam at 100 pounds pres­ of the wall would decay first. By dis­ sure is at 328° F. mantling several of these cabinets, we Steam under high pressure is the answer found the reason. at present to our sterilization problems, The change in temperature, after steam and not just ordinary steam. Upright has been introduced into a cabinet, causes boilers are made usually to work at 125 the moisture in the air within the wall pounds pressure and there is no reason to condense. Consequently, the interior of why they should not be worked at 90 to the cabinet wall, after the first use of the 100 pounds pressure in every-day practice. cabinet, remains wet, and under such a In this way you can make a small inex­ conjdition the interior of the cabinet walls pensive boiler working at high pressure deteriorates very rapidly. The reason that do the work of a large expensive outfit the outside wall decayed first was that the working at low pressure. inside w all was twice as thick as the out­ We know now that it is necessary to side, and therefore, lasted twice as long. use a medium size supply pipe and that The inside wall of a wooden cabinet releasing the steam through the small usually consists of sheathing diagonally holes spaced at regular intervals is not disposed and covered with % inch floor­ ing material in a vertical position. The only unnecessary but altogether undesir­ outside wall consists of weatherboarding able. If we use a % inch pipe, for in­ only. We solved that problem by Simply stance, inefficiency results; if we use a 1 designing a cabinet with the four walls inch pipe, there is too great a "carry­ as chimneys or flues. Instead of the air over” of water from the boiler to the remaining in the wall and forming water cabinet. Therefore, we have to strike a of condensation, the flue-like action of the happy medium. walls carried it out at the top of the cab­ Journal of Milk T echnology 17 inet and no dampness resulted. Wooden TEMPERATURE CONTROL cabinets of this construction, if made with Every cabinet should be checked by good material and properly operated, will the inspector with a portable recording last from seven to nine years. thermometer to determine 'its efficiency. The rusting of equipment was largely Cheap angle thermometers installed close prevented by cabinet design and operation. to steam inlets near the top of sterilizing It is just as necessary for a dairyman to cabinets are unreliable. learn how to operate properly a sterilizer "A chain is only as strong as its weak­ as it is for him to know how to operate est link”— and by the same token a steri­ a disc harrow. Neither is "fool proof” lizer is only as efficient as its doors. There and neither will operate by itself. The is quite an art in the building of a sat­ correctly designed cabinet should have two isfactory sterilizer door—one that will rabbeted doors, oppositely placed to allow not warp, one that will not sag or stick, cross-ventilation. The top of the doors one that will be efficient. should be as near the top of the cabinet as possible to prevent an air pocket form­ DOOR CONSTRUCTION ing above the door top level. In properly , In the early days most of our sterilizer operating a cabinet, both doors shuld be doors followed refrigerator door designs. opened at the end of the sterilization This was a mistake. Live steam is quite period in order that the retained heat of different from cold air. Any wood swells the sterilized equipment can drive off the in the presence of steam, and the steam, water of condensation and thus prevent in addition to swelling the wood, softens rust. This it will do very effectively. The , up its texture and predisposes it to warp- equipment should remain in the cabinet ing. until ready for use. After the doors are A correctly designed cabinet door is opened, however, copper screen inserts rabbeted all the way around. Space is should be placed in door openings to pre­ allowed between the edge of the door and vent recontamination of the utensils by side of the jamb for swelling. Experi­ flies. This will not interfere with the ven­ ence has shown that swelling takes place tilation of the cabinet, and the arrange­ away from the hinge side of the door. ment affords perfect storage for the clean­ Therefore, it is necessary to leave more ed and sterilized equipment. space on the latch side than on the hinge The two-door feature, provided the side when erecting the door. doors are oppositely placed, makes for With ordinary kiln-dried § 1 pine convenience that no cabinet should be construction, % inch space on the latch without. The one door , cabinet is unde­ side of the door between the edges of the sirable from every viewpoint; it never door and the side of the jamb is the cor­ ventilates and is always inconvenient. A rect clearance. While % inch clearance two-door cabinet with the doors in the on the hinge side is sufficient. One-half inch clearance at top and bottom is same side of the cabinet and only the milk sufficient although % inch clearance all house partition separating them is little the way around could be left without better than a one-door type, except pos­ affecting the efficiency of operation. sibly for convenience. To put two doors Efficiency does not depend on this clear­ in one side of a cabinet necessitates too ance, but on how well the door is pressed large a cabinet (or one that is all out of agkinst the packing on the rabbet—if proportion) for an average producer. It sufficient clearance is not allowed be­ is economically unsound to maintain a tween the edges of the door and the sides large heating unit for heating a lot of of the jamb, the door will inevitably stick. space that is never used. What some­ Sagging is caused by two things— weak times happens is that a small boiler is construction of the door itself and under­ coupled with a large box and inefficient hinging. If, instead of using two light sterilization results. hinges put on with wood screws, three 18 P ractical Farm Sterilization heavy hinges put on with lag screws are sure but what later proved to be air used, the trouble would be eliminated. pressure due to air expansion. The drain Most of the heavy doors in actual prac­ then acts as a safety valve and should tice are undjr-hinged, and therefore, sag. be left open at all times. The latch is an important factor in The drain should be large enough to sterilizer efficiency. The best latch, of accommodate the outflow of wash water course, is the heavy refrigerator door and admit of easy cleaning. About a latch that we see in large refrigerating 2" pipe has been found suitable for the plants. This latch is expensive, though, average cabinet. This drain if left en­ and dairymen hesitate to make the expen­ tirely open, permits too much loss of heat. diture. It is not necessary that the air escape A very satisfactory latch can be made valve be so large. Cap the pipe and by welding a malleable iron handle to a drill a suitable size hole in the cap 3 /l6 " x y 2" spring steel shaft. By bolt­ through which the air can escape. The ing this shaft to the jamb and by using a size of this hole as determined by- ex­ beveled piece of iron on the door itself, perience, should be one inch in we make a fulcrum that accomplishes the diameter for a 120 cu. ft. cabinet. With purpose splendidly. Two such latches this arrangement, we have a two inch on each door are necessary to insure drain—and a one inch safety valve. against warping of the door. SUMMARY DRAINS Farm sterilization can, at very little All sterilizers should be well drained. cost, be made efficient and convenient. A The drain serves two purposes: first, it chemical and two-door steam chest com­ facilitates cleaning with water under pres­ bination process of sterilization best ac­ sure ; and second, it allows for air expan­ complishes the purpose. The fact that lo­ sion—this is important! We have seen cation, construction, and design play a doors blown from their hinges by what most important part in the efficiency of we thought, at that time, was steam pres­ the equipment should not be overlooked.

STEAM CHEST FOR STERILIZING UTENSILS ON FARM Journal of Milk T echnology 19

New Creamery Butter Standards In order to provide a more direct, defi­ ty” 91, "definitely yeasty” 88, etc. Each nite, and accurate basis for grading of these specific flavor ratings from 93 to creamery butter than has heretofore ob­ 90 inclusive is allowed a tolerance or tained, the United States Bureau of Ag­ "defect” of y 2 point without any change ricultural Economics has issued "Revised in the score. Flavor scores of 89 and 88 Tentative United States Standards for are each allowed defects of 1 point, a Creamery Butter, Effective April 1, 1938.” flavor of 87 is allowed 2 points, 86 is The new standards involve changes in allowed 3, and 85 is allowed 4. These the score which has heretofore ob­ defects are the factors of body, color, and tained. They have been under considera­ salt, which' are given numerical ratings tion for several years. Last year nearly according to the degree of the off-quality. 275 million pounds of butter were scored The rating for body defects ranges from by the new method. The officials claim i/2 to 5 points, color from 1 to 3, and that the new standards represent a refine­ salt from 1 to 4. The score is determined ment and improvement of the previous by the following general rule: standards, and provide a more exact and The official United States score of an in­ simplified system of determining the dividual sample of creamy butter shall be official United States score. determined by deducting from the flavor rat­ An important new feature in the re­ ing of the sample the amount that the total ratings of the defects in body, color, and vised standards is a narrowing of the salt is in excess of the ratings for defects range of score for butter from the old permitted in these factors for butter of the basis of 75 to 95 points to a new basis particular flavor rating, the official United of 85 to 93 points. Furthermore, the States score to be expressed as a whole num­ package has been discontinued as a fac­ ber by lowering any half score to the next lower full score. tor in determining the quality of butter because it is not a constituent part of the This rule can be more readily grasped product and has no definite nor direct if it be expressed as a formula, as fol­ influence on its quality. Another fea­ lows: ture is the discontinuance of the score- Original) (total ratings of rating of allow-) flavoring)· — ^defects of body— ed defects fori card - method of prorating the score to rating ) (color, and salt, given flavor ) (A) , (x) (y) various factors, and the substitution there­ A — (x — y) final score for of a simpler and more direct method of rating each of the significant factors. A full explanation of the new method These factors are flavor, body, color, and of scoring, together with examples of its salt. application, and also a good description The scoring is made as follows: Each of the various defects and their causes identified flavor level of the butter sample are discussed in practical detail in the is first given a definite specific rating booklet mentioned at the beginning of which is based on the extent or degree of this article. This publication may be ob­ its development, as for example, butter tained without cost by writing to the with a "fine” flavor is rated 93, a "pleas­ United States Bureau of Agricultural ing” flavor 92, "fairly-pleasing” 91-90, Economics, Washington, D. C. "definitely acidy” 90, "slightly burnt-mal­ J. H. Shrader 20

Report of Committee on Ice Cream Sanitation* F. W. Fabia i, Chairman

Sanitation is based principally on three needed to increase sales. In medicine fundamental sciences, physics, chemistry, many lives could be saved yearly if all and biology. It can progress only as these physicians and surgeons would make avail­ sciences open up new avenues of approach able to their patients the latest scientific to the control of human and animal dis­ knowledge. Even bacteria when transfer­ eases. This has been demonstrated amply red from one medium to another undergo in the past in the control of infectious a period known as the lag phase in their and organic diseases. It was possible to grpwth. Ordinarily the lag phase is with­ reduce materially the death rate in such out serious consequence except where hu- diseases as tuberculosis and practically man life is at stake. In sanitation one of wipe out such diseases as typhoid, diph­ the most glaring examples of it is in the theria, smallpox, yellow fever, cholera, matter of pasteurization of milk and milk malaria and bubonic plague only after products. It has been demonstrated with­ the science of bacteriology had demon­ out any reasonable doubt that pasteuriza- strated the cause, and the public health tiqn is both an economic and a health official had applied this knowledge to the measure. When correctly done, it elim­ water, milk, and food supply as well as inates all the milkborne diseases, thereby to environmental factors such as sewage saying human life and needless suffering. and garbage disposal and insect control Yet, there are in the United States many such as flies, fleas, and mosquitos. cities in which only a fraction of the mar- Likewise chemistry has made its con­ kejt milk is pasteurized, and none of the tribution in many various ways such as other dairy products. Diseases such as in the eradication of deficiency diseases tuberculosis, undulant fever, and strepto­ and correcting nutritional deficiencies and cocci infection in humans ‘can be great­ in giving us new and better disinfectants, ly reduced by proper testing for these or­ to mention but a few of the many ap­ ganisms in animals, yet, many communi­ plications. Physics has aided us in dem­ ties have no well organized program for onstrating the role sunlight plays in such work. health, in providing means of duplicat­ Sanitary inspection of dairy farms pro­ ing a part of the sunlight by irradiation, ducing milk for use as market milk, ice as well as many other forms of energy cream, butter, and cheese as well as the such as radium emanations, Roetgen rays, sanitary inspection of the plants making Hertzian waves, electrical and heat energy, these products is considered an important all of which have been put to good use part of every well organized health de­ by the sanitarian. partment. Yet, there is scarcely a city in the entire country that has enough in­ THE LAG PHASE IN SANITATION spectors adequately to inspect the market In every line of work there is a period milk supply alone so that ice cream, but­ known as the lag phase. We have it in ter, and cheese are neglected. mechanics, in medicine, in biology, in sociology, and in sanitation. Many dis­ FOUNTAIN SANITATION coveries are made that are not applied Those familiar with the ice cream in­ immediately. In engineering many im­ dustry recognize that no matter how the provements are held in abeyance until ice cream may be manufactured, whether in a large or small plant or in a retail * Presented before the 26th Annual Meeting of store by means of a counter freezer, the the International Association of Milk Sanitarians» Louisville, Kentucky, October 11*13, 1937. dispensing of it by the retailer leaves Journal of Milk T echnology 21

much to be desired from a sanitary stand­ from large cans. More than 200 tests by point. This fact was first emphasized by the following simple, but effective, proced­ Horn5 in a paper before this Associa­ ure, determined what the real reason is. tion in 1935. Later, Fabian and Hook1 How It Was Done and Krog and Dougherty6 confirmed “One sample of loose ice cream was taken his work. with the vendor’s scoop in the exact manner In reply to a questionnaire sent out by that it would be served to a customer. A the Chairman to the Committee members second was taken with a sterile spoon, also Mr. Parker makes this pertinent observa­ from the top layer. Then two more simi­ tion : lar samples were secured from deeper down "We still go on piling requirements on after the surface layers of ice cream had the manufacturers of ice cream and supinely been scraped away with one sweep of an­ do nothing about the handling of ice cream other sterile spoon. All samples were ex­ in stores and other places where it is served. amined for numbers of bacteria by the ap­ ' Doctor Horn showed the importance of this proved agar-plate method. problem. The plain fact is that none of "Bacteria counts were invariably higher us know just how to deal with it. The in the scoop samples than those taken with serving spoons are used for long periods the sterile spoon; in some cases they were without being washed or kept in running three hundred times as great. The surface water, and ice perhaps partly clean. The ice cream had more bacteria than that below washing of dishes of various kinds in which due, no doubt, to the previously added dirty ice cream is served is not covered. I have scoop water which evidently penetrated as sometimes thought that an appeal to the far as three inches. The number of bac­ manufacturers of utensils might interest teria in the scoop water were usually found them in the problem. I believe that it was to be enormous, indicating that it was a the manufacturers of dairy equipment who good medium for their growth. are largely responsible for the excellence of sanitation in milk plants and dairies. I W h y It W as So believe that manufacturers might help out "Several other factors were found that in­ with this problem of dirty iCe cream dishes." fluenced the contamination of the ice cream. At the request of the Chairman, Dr. A. The smaller the amount of ice cream in J. Krog, one of the members of the the can the larger were the numbers of Committee, has prepared the following bacteria accumulated from numerous dip­ statement: pings.' Samples taken early in the day were “How a single step in the handling of usually best, presumably because the dip­ food can be the means of contaminating pers were washed and. clean water put in it is demonstrated by a study recently made the containers the first thing in the morn­ by' the Health Department of Plainfield, ing. The appearance of the scoops were New Jersey. In this case the step is the also a good index of the final degree of last one and the food is ice cream. contamination of the ice cream; when broken “Anyone who has given the matter a and mended with pieces of cloth or little thought must have concluded that the string, or when the working parts contained usual method of dispensing ice cream at slimy or Cheesy deposits, the counts were retail is a dirty one, due to the almost high. universal custom of keeping the scoops or "Some of the ice cream merchants in dippers, when not in use, in small cans of Plainfield were persuaded to try the plan water. The idea is, of course, to prevent of rinsing their scoops in running water the ice cream from drying and sticking to before and after each use, and between the scoops, not to keep them clean. times to keep them on dry racks protected “With few exceptions, ice cream in the from dust, flies and other sources of con­ small original packages was found to con­ tamination. A series of samples, taken in tain fewer bacteria than the same kinds, exactly the same way as before, showed from the same manufacturers, when served that this solved the problem. The bacteria 22 Ice Cream Sanitation

in scoops and sterile spoons were consid­ dinances covering the manufacturing of erably less, both on the surface and deep ip cream. Many of these laws or or­ down in the cans. dinances were enacted long before the "The picture that developed out of this advent of the counter freezer so that dis­ survey may be demonstrated by the averages crimination cannot be claimed in this re­ shown below which are based on one hun­ spect. dred samples of ice cream dispensed by the An interesting case in point is the city old method by which the scoops were kept of Birmingham, Alabama, which enacted in receptacles containing water, and one an ice cream ordinance out of experience hundred samples of ice cream taken by gained from a serious epidemic of ty­ scoops, which were rinsed in cold running phoid fever involving 350 cases in 1916 water before. and after each use and placed due to ice cream. After the epidemic an on a dry rack. ordinance was passed and operated suc­ "In this table it will also be noted that cessfully until 1935 when it was chal­ the average counts of ice cream sampled lenged by the installation of a counter with sterile spoons were considerably lower, freezer in a store operated by the Gil­ regardless of whether they were obtained christ Drug Company. Dr. J. D. Dowling, from the surface or sub-surface, than those the Health Officer of Jefferson County, taken from the same areas, with the vendor’s enjoined the Gilchrist Drug Company scoops. The answer to the problem will be pom selling the ice cream in violation of found in the average count of one hundred the ordinance. Relief from the injunc­ samples of water in which scoops were kept. tion was first sought in the lower courts and finally in the Alabama Supreme Average Count of 100 Samples piurt. The decree of the lower court Bacteria per cc. yvas affirmed by the higher court and the Scoop samples from surface...... 178,000 injunction was made permanent. Scoop samples from sub-surface 78,000 The section of the Birmingham or­ Sterile spoon samples from sur­ dinance in question was Section 5249 (g) face ...... 38,000 which is as follows: Sterile spoon samples from sub­ "Section 5249 (g). All ingredients used surface ...... 42,000 in the manufacture of ice cream or other Samples of water in which frozen substances, composed in whole or in scoop was contained...... 1,650,000 part of milk or milk products, shall be Samples from scoops stored on pasteurized as provided herein, and shall racks and rinsed before and flow or be conveyed through appropriate after each use...... 20,000 pipes or conveyors from the· pasteurizing What To Do About It apparatus directly into the freezing apparatus, "It is logical to conclude that we must , and from that directly into a sterile can, put into effect whatever new regulations are carton, or other final container, in such a needed to keep ice cream clean all the way manner as to protect same against contamina­ from the cow to the ultimate consumer. tion." Such action is no more than fair to the By another provision of the ordinance, public and evidently does not need to be a ice cream manufactured by any other hardship to those who make a business of method is condemned as insanitary, and selling this valuable product.” the manufacture and sale is prohibited. Expert witnesses called from many parts COUNTER FREEZERS of the country unqualifiedly endorsed the Counter freezers, one of the newer de­ continuous flow method as provided in velopments in the ice cream industry, still the ordinance. The complainant elicited presents certain sanitary problems to the from the witnesses the fact that they knew public health official due to the fact that of no epidemic attributable to the coun­ they do not conform to the requirements ter freezer or a case of typhoid fever contained in many State laws and city or­ that could be so traced. In this connection Journal of Milk T echnology ■ 23

Justice Gardner, who wrote the scholarly freezer type of ice cream manufacturing opinion for the Alabama Supreme Court, was not manufacturing within the scope says: of the Virginia Ice Cream Law. The "But we think complainant over-estimates Attorney General his petitioned the court the importance of such negative proof.” for a rehearing of tie case at which point "Perhaps, also in Mannix vs. Frost, supra, it now rests. \ the city in requiring milk dealers to cover Pennsylvania in July 1935 passed a or enclose the milk was likewise unable to new state law covering ice cream. Mr. trace any particular illness to that source. Irwin, one of the Committee members, But, observed the court, 'the police power was asked to comment on it for this re­ of a city means a power to prevent an an­ port. His comments are as follows: ticipation of danger to come, an active and “The subject of counter freezers is still earnest interest to protect the people, and unsettled in Pennsylvania, as well as many in so doing to curb and restrain the in­ other places. The state Jaw under which we dividual tendency.’ The Mannix Case was operate requires that the milk products used decided twenty years ago, and the require-, in the preparation of ice cream shall be pas­ ment that milk sold to the public in cen­ teurized before or during the preparation of ters of large population should be protected the ice cream. The rooms of buildings in from exposure, was vigorously contested; which ice cream is exposed during and after and yet there would be few today bold preparation shall be properly lighted, ven­ enough to question the wisdom of such a tilated, drained, clean and shall be used for precautionary measure. no other purpose than jo provide a place "Rapid advance has been made in the for cleansed containers aid utensils and for science of medicine and in the field of the handling of ice cream. The ice cream, bacteriology. That the health and welfare during and after preparation, and cleansed of the people have been greatly advanced by containers, utensils and Equipment shall be the conscientious and intelligent labor of the protected from flies. The; plant in which ice scientists and members of the medical pro­ cream is prepared shall be provided with an fession cannot be open to question. Their adequate supply of stearri and hot water for labors are not to be restricted to curing cleansing containers, utensils and equip­ disease and alleviating suffering, however' ment. Equipment with; which ice cream important these may be, but the greater comes in contact shall be constructed in benefits are to be realized by the use of such a manner as to he easily cleansed. preventative means in anticipation of the Demountable apparatus, with which the ice danger of an epidemic. And it is fully as cream comes in contact shall be taken important that the health authorities should apart and cleansed each day such apparatus anticipate danger to public health, and pro­ is in use. Surfaces with which ice cream vide against them, as it is to take steps to comes in contact shall be of smooth non- eradicate conditions after the disease has corrosive material andjfree from open seams. appeared. The plant in which ice cream is to be pre­ "An array of experts have unqualifiedly pared shall not be constructed nor altered un-' endorsed the continuous flow method, and til the plans and specifications thereof have have given their reasons for condemning the received approval ol the Secretary of Health. counter freezer method, now in use by com­ Equipment before ieing installed shall like­ plainant. No one can doubt their high wise be approved by the Secretary. standing in their chosen field, nor their “We have had the! above requirements sincerity of purpose, and lack of any selfish and the state law since July 1935. We motive.” are making progress slowly and I believe Another case of litigation over the that the general requirements of the Act counter freezer is that of F. A. Robert­ are sound from a public health standpoint son vs. Commonwealth of Virginia be­ and are acceptable to the\ manufacturers. It fore the Virginia Supreme Court at Rich­ is apparent, however, that the counter freezer mond. The court held that the counter cannot be operated on the store room coun­ 24 Ice Cream Sanitation

ter as was originally ptended. It is proving "All of ten or more years ago, trouble successful, however, when placed in a room ryith milking machine rubber occurred when provided for the pu/pose.” chlorine washes were used upon quiescent One of the reasohs given by operators rubber; pulsations and movement of such o f counter freezers; for noncompliance to treated rubber surfaces permitted seeding city ordinances repairing pasteurization of vj'ith small, surface, crack-imprisoned con­ the mix on the premises where the ice taminants with resultant pin points and cream is frozen is that there is no suit­ ojher high count difficulties. Heating as by able machinery for pasteurizing and prop­ pasteurization of rubber equipment corrected erly handling smill amounts of mix. The the trouble. machinery used iby wholesale manufac­ “In pasteurizing vats and other metallic turers is too large and too expensive to equipment subjected to changes of tempera­ meet their requirements. A machine has ture, repeated occurrences of bacterial count been designed tjhd placed on the market difficulties came from small cracks in vat which is a combination of a pasteurizer, walls, paddles, pipe lines, floats, etc. Sus­ holding vat, cooler and storage tank all picion, at times, indicated that certain chem­ in one. They mnge in capacity from ten ical sterilization solution actually entered gallons costingj|300 to 300 gallons cost­ into the dairy products from certain es­ ing $1125 wi:h intermediate sizes and tablishments; a. possible excuse .{jeing that corresponding jjprices. They are being sqch was unavoidable. There was at least used in Baltimore whose city ordinance re­ a limited belief that if some of this solution quires pasteurization' of the mix at the was 'accidentally' allowed to become a part place , of freezing. This is certainly a step of the finished product, lower bacterial in advance and will enable the counter counts would result and that health officials freezers to meet more nearly the require­ wpuld not be able to detect such a practice. ments of such ordinances. The merit or lack of merit in such an opin­ ion is not of moment; of actual import was CHEMICAL STERILIZATION a sincere opinion that chemical means were Chemical sterilization is a subject which used to attempt some control of faulty or is of interest to all of us. Most of us careless environmental sanitation. are familiar with its uses and abuses in the dairy industry. A great deal o f time “Added to this was the lack of definite and study has been devoted to it and control over standards of solutions; differ­ several new preparations of merit have ences existed years ago (as even now) as recently been placed on the market. Time to the parts per million of residual chlorine nor space will hot permit of giving it. that a disinfectant solution should carry. adequate treatment in this report. Those Variation from 25 to 300 parts per mil­ o f you who are interested in the subject lion, or over, are usual experiences. A are referred to the many excellent papers variety of preparations of different strengths dealing with the subject. of powder or liquid form, etc., all intro­ California does not permit the sub­ duce a situation impossible to control prac­ stitution of chemical sterilization for steam tically. Furthermore, atmospheric exposure sterilization. For this reason your Chair­ of chlorine compounds leading to decreasing man has asked one of the Committee, Dr. strengths of available chlorine is a usual R. V; Stone, from hat state to outline condition. in brief .their reasons. Dr. Stone’s com­ "Thus, when solutions are made up from ments are as follows: directions on the package (which is usual) “Fundamentally, for many years, the Cali­ by so many 'tablespopnfuls' or other bulk fornia Dairy laws have included the regu­ measurement, the actual available chlorine lation that steam must be used for sterili­ resultant is a matter of no control. The zation purposes. Any exception to this was compulsory and careful use of ortho-tolidine a method 'acceptable to the state’ but no such control of solutions by the producer of a official exemptions became recognized. dairy product is difficult to accomplish. Journal of Milk T echnology 25

Variation in temperature introduces more "WHY AND HOW CLEAN?" After variables. equipment has been used, there remain cer­ 'The effect of organic matter within a tain residues which, bacteriologically speak­ dairy product present as a residual in or ing, are referred to as 'dirt’ or 'sediment' upon production-soiled equipment influen­ and which must be immediately removed or ces again the actual effective chlorine avail­ prepared for removal. Residues present have able for bactericidal effect. Inspection evi­ been divided as follows: dence indicates that chemical sterilization 1. Sediment or milk solids which hang is used as a means of overcoming poor wash­ to the surface by means of an oily ing, an inadequate equipment or method. film, acting somewhat as a binder. A course of least resistance attitude 2. Sediment or milk solids which are has been evident upon occasion where the held to the surface by absorption. slopping around of a chemical sterilizer 3. Milk stone deposits. was taken as a means to control all ills.” "It has been our observation that there Mr. Fred W. Milner, ice cream specia­ is not always an accurate conception of what list, California State Department of Ag­ is meant by proper washing and sterilizing. riculture in a lecture of the short course, There are two distinct operations. Cleaning University of California, College of Ag­ can not be accomplished by sterilization, nor riculture, Davis, January 1937, stated: can proper sterilization be. effected without . . . . "The chemical action of a deter­ proper cleaning. The complete removal of gent creates a solvent action by rendering in­ all milk solids before sterilization cannot be soluble substances soluble and which can be over-emphasized. If the equipment is not removed mechanically. properly washed and sterilized, bacteria "In the washing of equipment, I wish lodge and develop in the film of dirt or to emphasize the fact that the detergent or grease on the surface, and they are protected cleanser does not clean the equipment but from the penetration of the heat. We must really prepares the sediment for its subse­ bear in mind that naked bacteria are easily quent removal by adequate scrubbing with killed. However, when they wear a coat of a stiff brush and rinsing. Bear in mind that grease or film of milk solids, they are pro­ there is no substitute for old-fashioned elbow tected and will remain unharmed by the grease. In some instances, operators of small sterilizing agent. freezers have resorted to the use of soap "I asked Mr. Milner to visit me in order powders. Such products are good emulsi­ to discuss this 'why heat only’ in California fying agents but form greasy insoluble films, practice. On July 29 we glanced through very much similar to milk stone, thus a great deal of data which showed very high creating a harboring place for the bacteria. counts in ice cream from counter freezers "Sterilization is Important. The next im­ where chemical sterilization had been used portant step in the proper handling of the and which counts dropped dramatically upon equipment after a thorough cleansing is compliance to the demand that heat be sub­ proper sterilization. Sterilization is a pro­ stituted. cedure which involves the destruction of "Out of 785 producing establishments in­ bacteria by heat. California laws require that spected by the State Department of Agri­ all equipment, if properly sterilized, must culture in California there was provided ap­ be heated to a temperature of not less than proximately 10,000 ice cream samples. Of­ 170 degrees for a period of not less than tentimes, the same day, the same street, and 15 minutes, with either hot water or steam. the same flavored product, such as vanilla, If this is properly done, the equipment will yielded high versus low counts in parallel be so hot that all moisture will be removed. with chemical versus heat sterilization. These It is this drying effect that prevents bac­ high counts dropped to low counts upon teria from multiplying.” changing methods. Further, in his published article in "Mr. Milner’s observation that those who Ice Cream Trade journal, April, 1936, he followed the 'course of least resistance’ and stated: used chemical only had grief while those 26 Ice Cream Sanitation

who had followed the heat treatment pro­ has found its way to many and varied- lo­ gram seldom met with production high cations. Too often the manufacturer of ice count problems. cream, who has just recently entered the "Bacteria require food, moisture and opti­ business, is not a trained dairyman, does not mum temperature for growth promotion. Re­ realize the importance of the place that the move the food mechanically by cleaning, re­ industry holds in our national life and, move moisture by heat, and the bacterial as a result, regards his particular business counts will be adequately taken care of.” from a purely local viewpoint with the thought in mind of trying for a personal TOTAL FOOD SOLIDS STANDARD FOR adyantage or gain, even though only tem­ IC E CREAM porary, with little or no regard for the wel­ Last year in our report the subject of fare of the industry as a whole. controlling overrun in ice cream was dis­ “Therefore, it was necessary to revise cussed at some length. This is a subject existing ice cream regulations so as to fit which is receving considerable attention the present stage of devlopment in the in­ at present in many places. The Federal dustry. It was realized that such revisions as Government in Canada has been making were necessary should regulate but not re­ a study of the whole subject with a strict in any way the normal, sound growth view of regulating the amount of over­ of the industry. - run. Mr. W . C. Cameron, one o f the "A survey of the industry revealed the members of our Committee, who is Chief incprporation of excess air in ice cream as Inspector of Dairy Products of the Fed­ being the phase of ice cream manufacture eral Government at Ottawa, has been in whpre the greatest variation existed. Hence, close touch with the work. The Chair­ some method of regulating overrun in ice man, therefore, asked Mr. Cameron to cream was considered necessary. report on this phase of the work. His ''The various means of regulating the report is as follows: amount of air that may be legally incor­ "The ice cream industry in Canada has for porated in a mix while being frozen into ice a considerable time been subject to com­ cream was studied. This was done with a paratively few regulations either as to com­ vieyf towards determining which method position of the finished product or sanitary would exercise adequate control over the requirements. This condition, though not amount of air in ice cream and at the same desirable, did not, until recently, result in tim,e meet the following requirement which an inferior product being offered for sale, the industry deemed necessary: nor was it prompting any undesirable prac­ "'The consumer should be assured of a tices in the trade. This was due to the fact reliable product and in no way be exploited that the manufacture and distribution of for the gain of any other section of the in­ ice cream was in the hands of compara­ dustry—the manufacturer who wishes to use tively few well established dairy companies, a mix of high total solids content should who, as a general thing, assumed the atti­ be compensated for the extra cost so en­ tude that what was best for the industry tailed without increasing the price of ice generally would result in direct benefit to cream to the consumer—the use of more milk their own private interests and hence, quality products should be encouraged—no restric­ both as to composition and sanitation was tions should be placed on the development maintained at a high level. of new or advanced methods of manufac­ "As new developments, both in the ice ture which might embody the use of more cream industry and also in allied trades, air in ice cream, providing the finished pro­ made their appearance, such as certain adap­ duct contains a definite minimum of food tations of machinery, advances in mechanical value—-there should be a certain elasticity refrigeration, cheap non-returnable contain­ in 1'he definition for ice cream which would ers, and by no means the least, a gradual permit the adjusting of ingredients to meet change in the mode Of transportation, the the varying demands of the'consuming pub­ manufacture and distribution of ice cream lic which appear to differ depending upon Journal of Milk Technology 27

location and climatic conditions^ice cream ment for ice cream automatically places a should be so manufactured as to induce the maximum limit on the amount of air that maximum consumption per capita. can be incorporated and also the minimum ■ "The one method of controlling the weight of a unit volume of ice cream for amount of air in ice cream which appeared, each and every type of mix used. It does capable of meeting the requirements of the foster the use of more milk products which industry as stated above was that in which should be reflected in a distinct benefit to ice cream is required to contain a definite producers. minimum weight of food solids per unit "There was one question which was up­ volume. permost in the minds of those responsible "The amount of food solids alone is not for approving the method of controlling sufficient to ensure a good ice cream. There overrun by the food solids requirement in must be some guarantee that they are the the finished ice cream and that was—Is there right kind of food solids. The nature and a maximum overrun that can be taken on the amount of the various solids contained ice cream regardless of the richness or total in ice cream may be controlled within lim­ solids content of the mix beyond which its by so drafting the definition for ice the body and texture of the resulting ice . cream as to stipulate the ingredients from cream suffers and which would permit plac­ which it may be manufactured and in - so ing on the market an ice cream with an doing specify . the minimum percentage by undesirable body and texture, not palatable, weight of fat and total , solids and also the and which would tend toward decreased con­ maximum percentage by weight of stabilizer sumption ? permitted·. At present, it is believed that the "A limited number of experiments con­ proportions of the solids in ice cream other ducted in a commercial ice cream plant than fat and stabilizer, will be regulated by showed that properly balanced mixes frozen consumer preference and the resulting body with modern machinery gave ice creams (in and texture of the finished product. It is which overruns varying from 100 to 152 also felt that the introduction of unde­ per cent had been taken) which were almost sirable solids into ice cream is not a serious identical as to body, texture and palatability. possibility at present. Judged by a number of employees from both "It may be, however, as more study is the plant and the office, including a fair given to the problem, and. with certain new percentage of women who were taken, as possible developments, that a more specific representing the average consumer and also statement will be required as to just what by men considered to be authorities on com­ shal} constitute the food solids in ice cream. mercial ice cream, it was revealed that when Should there be a tendency to increase the the finished ice cream had the required food total solids in a mix at the expense of milk solids per unit volume and was manufac­ fat, then a statement will be required stipu­ tured from what was considered well bal­ lating the proportion of milk fat that shall anced mixes, that the amount of air incor­ be present in the total solids of ice cream. porated did not have any undesirable effect . Such a statement may also be required for on the finished product. The majority, picked milk solids not fat. Further, it may be that the high overrun ice cream manufactured the 'flavors’ used for ice cream may require from a mix of corresponding high per cent. modification should there be any attempt at total solids as being the best product. adulteration with certain products disguised "At the present time, it appears as though as 'flavors.’ a comprehensive definition for ice cream "From the standpoint of the manufacturer which embodies the feature of requiring a and the producer, the food solids require­ minimum of food solids per unit volume will ment for ice cream does compensate a manu­ regulate overrun, will permit adjustments facturer for using a richer mix by permitting of the mix to meet the various demands a higher overrun. But a limit is placed on of the consuming public in different lo­ the amount of air that can be legally incorp­ calities, will foster the use of more milk orated. Actually the food solids require­ products in ice cream, will permit sound 28 Ice Cream Sanitation

developments in manufacturing processes, 4. Potential possibilities for contamina­ will stimulate consumption and prevent tion of these ingredients exist. We should fraud or the exploiting of the consuming not wait until somebody contracts a dis­ public.” ease by eating ice cream in order to get MATERIALS ADDED AFTER proof and in order to start in to correct PASTEURIZATION the situation. Last year in out report2 attention was 5. Much can be done by the ice cream called to the sanitary problem existing in plants themselves, such as: relation to the addition of law products .(a) Keep the ingredients under proper to the mix after it had been pasteurized. sanitary conditions. The addition, during the freezing process, (b) Treat the ingredients in some of nuts, fruits, extracts, and coloring ma­ manner to keep them safe. terials that contain many organisms, some of which may be pathogenic, is not a safe (c) Purchase only good products procedure and should be corrected. It has from houses where some effort been shown by several investigators, Fa­ at sanitation is being made. bian3, Newman and Reynolds7, Prucha8, (d) Use good ingredients in the mix, Prucha and Tracy9, Smallfield10, Tracy12, properly pasteurized mix, and and Brown1 that the ingredients added efficient safeguards'*' against the after pasteurization may contain many bac­ contamination of the ice cream teria and a certain percentage of the sam­ so that ice cream can be made the ples contained the Escherichia-Aerobacter safest food on the market, the group. The way in which the materials goal for 1937. were handled led the investigators to be­ lieve that undoubtedly some of the Es­ SOLUTION OF THE PROBLEM cherichia coli were of human origin. It is evident from these conclusions and Brown1 has shown that two pathogenic also from the observations of other in­ organisms Staphylococcus aureus and Eber- vestigators that here is a problem that thella typhosa when inoculated into three exists and one that should be corrected, different shades of coloring materials were lyiany manufacturers of -ice cream say capable of surviving for a period of two when approached on this subject that if weeks although the numbers decreased ypu tamper with fruits you immediately rapidly during the storage period. destroy the real fruit flavor. Prucha8 in discussing the materials They also contend that nuts become added after pasteurization o f the mix from soggy and less brittle when treated. Flav­ the public health standpoint reaches these oring extracts, since they are made with very important conclusions: ethyl alcohol and are also volatile, lose In concluding this discussion on the sani­ rquch of their value when treated. Col­ tary aspects of the fruits, nuts, flavors, oring materials while they are less sensi­ and color’s, the following comments might tive, may likewise be impaired by any be made: germicidal treatment. What are the facts 1. There is no definite evidence that in the case? ■ these materials had infected ice cream with Brown1 has found by extensive ex­ disease bacteria and that such ice cream periments that it is possible to reduce caused epidemics. greatly the bacterial content and improve 2. The plants where these materials are the sanitary quality of all the materials handled and prepared are not properly con­ added to the mix after pasteurization trolled by the health officers. •without materially affecting the quality or 3. The storing of these ingredients in flavor of the product. In fact some of the ice cream plants should be inspected the materials such as pecan nut meats and controlled by the health officers and were actually improved in flavor after by the ice cream plant superintendents. such treatment. Journal of Milk Technology 29

Time will not permit to go into de­ PROPOSED NEW MEDIA AND tail regarding the methods used by Brown INCUBATION TEMPERATURE to improve their sanitary quality but his For the past several years the Standard conclusions which should be of interest Methods Committee on Milk Analysis are as follows: .of the American Public Health Associa­ 1. The three methods of preparing pe­ tion has been studying new media to re­ cans for the cracking process that were place standard agar which has been used studied injured the texture of the hut for many years and which they believe meats. has outlived its usefulness. They have 2. The sanitary quality of pecan nut been studying also a more favorable in­ meats can be greatly improved by dipping cubation temperature. The new edition in a 50-75 per cent boiling solution of of Standard Methods of Milk Analysis sucrose plus 1 per cent salt followed by which is to be issued shortly will not con­ drying in a hot air oven. (Details found in tain any change in the present medium his Table 2). A marked improvement in or incubation temperature but. a change the flavor of the · nut meat usually results will be made in the future without a from such treatment. doubt. 3. The treated meats can best be stored There are two different opinions in glassine bags at room temperature. The amongst those interested in this ques­ relative humidity should be around 42 to tion. The first group consists chiefly of 50. milk control officials who have built up 4. One-tenth of one per cent of sodium a set of bacteriological standards around benzoate added to coloring materials will the present standard medium. They con­ not inhibit the growth of bacteria. tend that the introduction of the proposed 5. ' The addition of 25 per cent alcohol changes in the medium and incubation to coloring materials will prevent the growth temperature will disrupt their standards of bacteria and mold. and throw the whole milk question in 6. Coloring materials can be heated to chaos. Another group opposing the pro­ 140°, 160°, or 180°F. for 30 minutes posed changes is the dairies buying milk without injuring the quality of the colors. on a quality basis. Here it will likewise Additional heating, in some cases, slightly result in some confusion at first. A reduces the intensity of the color. third group are laboratory workers who 7. Strawberries and raspberries can be see at this time no reason for changes pasteurized to 140°F. for 30 minutes to which will necessitate the use of two or improve their sanitary quality when used more incubators run at different tempera­ to flavor ice cream. tures and cause considerable expense and 8. Peaches mixed with sugar can be confusion. A fourth group might also be •boiled for three minutes without injuring listed who oppose the proposed changes the flavor of the peaches. on general principles as they would any 9. The flavor of oranges is not affected change which would upset their routine. when dipped , in 75-100 parts per million Those who favor the proposed changes chlorine water to improve the bacteriological likewise have good and sufficient reasons aspects of the fruit for use in ices or for so doing. They argue that the present sherbets. medium gives only a small percentage of 10. It is possible to heat some of the the actual number of organisms present flavor extracts to 145 °F, for 30 minutes in the milk in most cases. Many bacteria without injuring the quality of the flavors. fail to grow on the present standard By requiring that all materials added agar. That the present standard agar to the mix after it has been pasteurized gives only a fraction of the number of be given such a germicidal treatment will viable bacteria present in milk has been remove the last weak link in the manu­ known for a long time by checking the facturing chain and insure a product that milk with the direct microscopic method is above sanitary reproach. of Breed. In fact, when the present 30 Ice Cream Sanitation standard agar was originally proposed in dards based on our present methods; (5) 1915, it was known by the Committee comparative tests made with the two med­ and others that the addition of nutrients ia at 32 degrees and 37 degrees C. have such as dextrose and m ilk would increase demonstrated that the better the quality the count many fold. Those favoring a of the milk, the less, difference there is in change contend and show by many ex­ the bacterial counts, whereas, the poorer periments that 37 degrees C. should have the quality of the milk the greater the never been used for milk work. It was difference in counts. One worker com­ originally used as a matter of conveni­ paring counts with the two media gave ence because most laboratories do other the following figures which illustrates this types of work such as pathogenic bacteri­ point: Certified pasteurized milk gave a al analysis, and need incubators at this 10 per cent increase, certified raw, 31 temperature. It is very convenient to per cent increase, Grade A raw 55 per place a few milk plates in these incuba­ cent increase, and ordinary raw milk be­ tors. That 32 degrees C. is a far bet­ fore pasteurization 62 percent increase ter temperature for the growth of most in the bacterial count when the proposed milk bacteria cannot be questioned. Nu­ new medium was compared with standard merous experiments show that many more agar. bacteria present in milk grow at this tem­ Finally, one country, ^England, has peratore than at 37 degrees C. A t the changed from standard agar to a new latter temperature it has been found that medium giving a much higher bacterial a two degree change in temperature either count than standard agar, and the Ameri­ side of 37 degrees C. greatly reduces the can Association of Medical Milk Com­ count, especially if the temperature is in­ missions has adopted a new medium creased, whereas at 32 degrees C. a slight which also gives a much higher count fluctuation in temperature, such as two de­ than standard agar formerly used by grees, either side of 32 degrees C , makes them. These changes give some indica­ little difference. A study of 37 degree tion of the dissatisfaction with the present C. incubators show such fluctuations are standard medium. the rule rather than the exception. F. W. Fabian, Chairman Other arguments in favor of the pro­ W. C. Cameron posed changes are in brief: (1) we are R. E. Irwin striving to increase rather than decrease A. J. Krog the requirements for good milk; (2) we J. M. Lescure want to use a medium and incubation Η . N . Parker temperature that will grow all the bac­ R. V . Stone teria present that should grow so as to P. F. Krueger know the real quality of the milk, so that then we can improve the milk supply; REFERENCES (3) it has been shown that with the pres­ 1. Brown, W. H.—This matter of mix. Ice ent standard methods of milk analysis, Cream Field. 31/ (3) 9-13, (4) 27-29 the bacterial counts of 50 percent of the . (1937). raw Grade A milk in 25 representative 2. Fabian, F. W.—New problems, in ice cities were below 10,000 per ml. This cream sanitation. 25th Annual Report. Int’I. would show that if these figures hold Assoc, of Milk Sanitarians, pp. 330-345 throughout the United States and Can­ (1936). ada, then much of the milk now pro­ duced in these countries would meet' the 3. Fabian, F. W.—Bacteria added to ice requirements under the proposed changes; cream in flavors and colors. Ice Cream (4) if a: change is desirable as most Field. 16: (6) 16 and 102 (1930). agree, then the sooner the change is made, 4. Fabian, F. W. and Hook, A. E.—Es- the better, before any more state and city cherichia-Aerobacter group in ice cream laws are enacted specifying bacterial stan­ (c) At the fountain. Proc. 36th Annual Journal of Milk Technology 31

Convention, Int’l Assn. 1. C. Mfrs. 2: 30-39 Rept. Proc. 36th Ann. Conv. Int’l. Assn. (1936). Ice Cream Mfr’s. 2: 40-45 (1936). 5. Horn, D. W.—Ice cream contamination 9. Prucha, M. J. and Tracy, P. H.—Un­ by dippers (in retail stores). Annual Re­ published data. Cited by Brown. See Refer­ port Int'l Assn, of Dairy and Milk In-,' ence No. 1, spectors. pp. 249-256 (1935). 10. Smallfield, H. A.—Bacterial contamination 6. Krog, A. J. and Dougherty, D.—Scoops of ice cream from color solutions. Ice as a source of contamination of ice cream Cream Review. 16: 42-43 (1933). (April). in retail stores. Jr. Am. Pub. Health Assn. 11. Tracy, P. H. and Prucha, M. J.—Are 7. Newman, R. W. and Reynolds, A. E.— flavor and coloring sources of bacteria in Bacterial flora of some ice cream ingredi­ ice cream? Ice Cream Trade Journal. 52: ents. Cal. Agr. Exp. Station Monthly 19: 17-18 and 20 (1936). 677-680 (1930). 12. Tracy, P. H.—^Study of methods used 8. Prucha, M. J.—The relation of fruit, to improve sanitary quality of nut meats, flavors, nuts and colors to the sanitary pro­ flavoring and coloring used in ice cream. duction of ice cream, (a) Importance of Rpt. Proc. 36th Ann. Conv. Int’l. Assn. problem from public health point of view. Ice Cream Mfrs. 2: 56-67 (1936).

Filled Milk Decision The Food and Drug Administration of jurious to public health and its sale con­ the U. S. Department of Agriculture stitutes a fraud upon the public.” warns that it . will institute legal action The indictment in the Carolene case against all interstate shipments of any alleged the unlawful interstate shipment product falling within the statutory def­ of “Milnut” and "Carolene” manufac­ inition of filled milk. tured by Carolene Products Company of The warning follows the recent decision Litchfield, Illinois. Analyses by the Food of the United States Supreme Court in and Drug Administration showed the the case of United States v. Carolene Prod­ ucts Company, which upheld the Federal products to be composed essentially of Filled Milk Act of 1923 as constitutional. evaporated skim milk and cocoanut oil in By its terms the Filled Milk Act pro­ semblance of evaporated whole milk. hibits the interstate distribution of any After prosecution was started, the manu­ combination of milk, cream, or skimmed facturer filed a demurrer to the indict­ milk, with any fat or oil, other than the ment on the ground that the act was un­ milk fat so as to resemble or imitate milk constitutional. The demurrer was sus­ or skimmed milk in any form. The tained by the Federal Court for the South­ legislation was enacted after a Congres­ ern District of Illinois. The United States sional hearing. Congress determined and ' appealed to the Supreme Court of the declared: "That filled milk, as herein de­ United States which upheld the Filled fined, is an adulterated article of food in- Milk Act as constitutional.

Do you know the official procedure for making

VITAMIN D BIO ASS AYS?

See the March issue of this Journal 32

Modern Methods of Milk Plant Inspection Maurice H. Shorago Consultant to the Dairy Industry, Boston, Massachusetts

It has been said, and aptly so, that the teurized shows a predominance of what modern public is one of the best regula­ appears to be lactic acid bacteria, the in­ tory forces where foodstuffs are concern­ fection has taken place after pasteurization. ed. The indifferent plant operator soon This statement is based on the assump­ finds that his carelessness pays dividends tion that the phosphatase test on the in the form of loss of revenue and good sample has been negative. If, however, will. Since, however, we have hardly samples were taken of each successive vat reached the Utopian age where we can of milk pasteurized, and then have been permit men to wholly regulate their own mixed with resazurin dye and incubated, actions while engaged in any industry we can determine whether a thermophilic affecting public health, it is necessary to infection is present. The two’instances have inspectorial forces supervising such cited call for two different types of in­ activities. It is possible, by the "police” spection. In one case, the trouble will method, to catch the unscrupulous opera­ usually lie in an unclean distributor pipe, tor but what usually happens is that this pump, or other apparatus used in handling type, with the technical help available, the milk after pasteurization, or, in some can if they so desire, circumvent control. cases, the filling of buttermilk prior to ■This of course is not the end desired. millc. Instances have been found where When improper methods are found and a the filler has been thoroughly washed correct solution offered, the suggestions but the filler rubbers were not removed. have usually been followed in good faith. In the case of thermophilic contamina­ tion, laboratory pasteurized samples are to To carry out properly the duties of an inspector, it is necessary to keep posted . be examined and the plant inspected for milk stone. As a concrete example, an on the literature pertaining to the indus­ actual case may be cited: try, attend technical meetings, and take Plant "A” was receiving continued bac­ part in an interchange of information. By terial reports of an unsatisfactory na­ using practical tests now available, the ture. The State Department of Health work can be performed in an intelligent checked the raw milk supplied to this manner. plant and found that in all cases the pro­ Before making a physical inspection of ducers were shipping milk having a plate a plant, it is necessary first to examine count of less than 40,000 colonies per cc. the accumulated reports on the plant and In spite of this, however, the pasteurized products in question. The use of the milk on the same day showed a count in resazurin test in conjunction with a mi­ excess of 500,000. Before making a croscope has proven of invaluable aid in physical examination of the plant, samples gaining quick information. A follow-up were taken of raw milk in the mixing check by use of the phosphatase test will vat, and checked by means of the resa­ offer a picture as to whether the pasteuri­ zurin test. This same milk was followed zation process is being completely carried through the system and samples taken out or, as has been found in some in­ from the filler at such time as to coincide stances irregularities, intentional or unin­ with the jinflux of milk from successive tentional, are indicated. vats. All samples were immediately cool­ It is obvious that if a microscopic smear ed and held for the resazurin test. The of the milk presumed to have been pas­ results were quite dramatic: Sample No. Journal of Milk Technology 33

1 representing the first milk through the Dum p tanks and w eigh scales·, offer system gave a distinct blue color while many points of possible trouble, such as successive vats gave increased change in non-removable valves and corners of color until the last sample which ran (, screening. Because nothing but cold milk white. It was obvious that since all vats ever touches the surfaces of this type of of raw milk were apparently of good equipment, there is no excuse for any. bacteriological quality, we were getting accumulation of milk solids. growth at some point during the process­ Raw milk pumps (and lines) are more ing period. A follow-up physical inspec­ often neglected than those handling pas­ tion revealed the fact that there was a teurized milk. The general impression thermophilic infection having its origin seems to be that the pasteurizing system in a thermometer retaining nut in the w ill take care of any oversight at this preheater. This, coupled with the fact point. This same opinion, apparently, that milk stone was found on the inner seems to hold where filters and clarifiers edges of the distributor pipe holes and are concerned. Based on actual experi­ also on the upper edges of the plate-type mental and practical experience it would heater was sufficient to give information seem that any plant handling more than necessary to eliminate the trouble. 4,000 quarts of milk per day should be In a routine physical inspection of a using cold milk clarification. It is realized plant about which there is no informa­ that this is a controversial point. It tion, w e must begin at the tank trucks, is the author’s Opinion that there is no tank cars, or storage tanks. One o f the justification for pumping clean milk thru greatest difficulties encountered with the a filter, hot or cold, that may possibly tank car is dirty air lines leading to the have its surface inpregnated with dirt tank. Often these lines are not cleaned for from the milk of a careless producer. Hor long periods of time, and actual cases of milk filtration is a subject that should be green mold have* been found. General dignified by discussion. sanitation of the tanks, of course, must The subject of preheaters is rife with be checked. possibilities. The plate type preheater, or One of the most common faults in cer­ regenerator, is easier to inspect and prop­ tain types of tank trucks is that the opera­ erly cleanse than. the tubular types, re­ tor of the truck does not take time to gardless of make, and therefore offers replace the cap on the outlet pipe, and less possibility of trouble. It is important on the trip through the city streets var­ to remove completely and disassemble all ious1 types o f road dust and dirt are picked thermometers in this type of equipment up. Outlet valves of these trucks are many because it is usually at these points that times neglected, particularly the springs difficulty is encountered. Gasket inser­ and rods. The commonest fault, in the tions must also be carefully watched. Tub­ washing up of storage tanks is that so ular preheaters, on the other hand, usu­ called "leak-proof” thermometer recep­ ally give trouble at those points where tacles belie their name, and when these the tubes are inserted through the header, are not regularly removed and washed, a resulting in a small crevice. source of infection results. Leaky stuffing Pasteurizing vats of all makes seem to boxes on agitator shafts are another com­ be neglected most at the insertion of the mon source of infection and must be outlet valve. For some unexplainable reason, men will spend hours scrubbing checked carefully. In the older type equipment thoroughly and then undo tanks, manhole gaskets are often neg­ whatever good has been done by neglect­ lected. Of all possible points of infection ing the short surface between the inside of in this type of equipment, the sampling the tank and the valve. While on this petcock seems to be the greatest offend­ topic it should be unnecessary, in view er. It is beyond my understanding why of the recent rise to popularity of the certain types of petcocks are permitted. phosphatase test, to caution about check­ 34 Milk Plant Inspection ing the clocks of the recording thermo­ amount of pressure inside the cooler meters, as well as apparent holding tem­ while no milk is flowing over the out­ peratures. There is, even today, equip­ side. In this way, small leaks can readily ment being installed which provides no be found. Plate coolers are checked in means of adjusting the temperatures of the same manner as plate heaters. milk, once it has reached the holding The usual points neglected in milk tanks, nor is there any method provided fillers are the valve sleeves and the inside for agitation during the holding period. portions of the overflow pipes. It is a Unless an inspector can actually find milk simple matter to check these. In some running into the filler before it has been cases where trouble has been present, it heated and held properly, it is difficult, was found that the filler was first being except through the use of the phosphatase used for cream or buttermilk or similar test, to locate the difficulty. In plants by-products, carefully washed and steril­ where milk is being preheated to the final ized, and then used for milk. The valve temperature before entering the vat, it is rubbers, however, were not removed, and impossible for an inspector to determine small amounts of the former were held at what time the vat was filled and con­ in these points and slowly discharged into sequent holding time began. The practice the following milk. In one type of va­ of preheating to a few degrees lower cuum filler, milk has a tendency to back than the required temperature and then up into the air line. Unless this line is polishing off in the vat will automatically kept scrupulously clean, a foul odor will show when the holding time began. result. This can best be determined when Milk pumps which are so constructed the machine is empty. as to allow milk to gain entrance to parts One point usually neglected by the inaccessible to clean-up operations have average inspector is to determine whether no place in the well regulated plant. These contaminated water is being used for can very readily be detected by examining washing purposes or whether there are any the grease cups (looking for an admix­ cross connections between City water lines ture of milk) or the motor end of the and well waters. The recent Chicago shaft. All pumps should be checked care­ epidemic points to the significance of fully. extreme care in the selection and main­ Another source of great trouble has tenance of water supply lines. This is par­ been the practice of making distributor ticularly true in a dairy plant because, of pipes from one to two feet longer than the possibility of the spreading of con­ the tubes of the surface cooler, creating tagion. pockets or dead-ends in which milk can There are many types of bottle washers, lie for long periods of time, dropping in each of great value in its particular field. temperature and offering a breeding The greatest difficulty seems to be in the ground for bacteria. This difficulty can proper maintenance of these washers. It be readily remedied by either shortening should be ascertained that the correct t'he pipe or filling each end with a remov­ amount of caustic is used at the proper able plug. Particular attention must be temperature and that either the bottles paid to the holes in the distributor pipe, are subjected to sufficient heat (and caus­ because these small spaces tend to accumu­ ticity) to kill pathogenic organisms or late milk-stone on their edges. Surface that, preferably, chlorine sterilization be coolers should be checked so that milk practiced. is not allowed to splash off of cat-walks The correct routine for washing up a or end guards and then drop back into plant and equipment depends on the type the cooler trough. This has been the of equipment used, i.e., tinned copper, cause of a great deal of difficulty. Cab­ glass, or stainless steel. After carefully inet coolers, particularly the type made of checking most of the washing compounds very thin gauge material, should be sold today, it is the author’s experience checked occasionally by putting a small that "elbow grease” is still the main in­ Journal of Milk Technology 35 gredient for any successful washing com­ Metropolitan Dairy Technology Society pound. If care is used to see that all hot The Metropolitan Dairy Technology milk handling equipment is immediately Society recently elected the following cooled following the run of milk, the officers for the ensuing year: Dr. J. H. wash-up job will be made much easier., Shrader, president, succeeding Professor It has been found that chlorine steriliza­ F. C. Button; Dr. C. H. Kimberly, vice- tion by far offers the greatest protec­ president; Dr. O. F. Garrett, secretary- tion. If sufficient hot water (not just hot treasurer; and D. F. Snyder, sergeant-at- to the hand) were used, there is no ques­ arms. The society meets on the third tion but that proper sterilization would Tuesday of every month in the McGraw- result. However, a temperature high Hill Building, New York City. Dinner enough to sterilize dairy equipment is at 6:30 precedes the meeting. The mem­ dangerous to use because personal injury bers are engaged in some phase of milk to the workmen may result. One in­ technology or in a closely allied subject. stance has been noted where steam, under Visiting milk sanitarians are cordially in­ partial pressure, has been used and where vited to attend the meetings. These be­ m ilk immediately follow ed. The first gin at 8 o’clock, each with a paper by milk striking the groove inlet valves was some well-known worker in the dairy immediately cooked on and obstructed the field, and this is followed by an informal correct operation of the leak detectors. discussion in which the membership quite Because of limitation of time and space, generally participate. no attempt has been made to cover thor­ oughly all equipment used in the dairy Hiscock Elected President of National industry but rather to indicate those points Health Council which usually present the greatest diffi­ Ira V. Hiscock, professor of public culty under actual operating conditions. health in the Yale University School of It is obvious that regardless of the ex­ Medicine, has been elected president of perience and training of the inspector, the National Health Council for 1938, unless he gains the willing cooperation succeeding Dr. Donald B. Armstrong, of the plant operator, it will be well nigh vice-president of the Metropolitan Life impossible to cover thoroughly all plants Insurance Company, who becomes a mem­ in his territory. Here might be pointed ber of the Council’s Board of Directors. out the value of willing cooperation, —Health News, Albany, N. Y. thereby enabling the inspector to devote his .time toward supervising recalcitrant Corbin Elected Sheffield Vice-President plants. There is absolutely no reason Dr. C. I. Corbin, an .associate member why any plant properly designed and of the International Association of Milk having the proper equipment and care, Sanitarians, has been elected a vice-presi­ cannot produce safe wholesome milk of dent of the Sheffield Farms Co. He the kind which will tend to increase con­ joined their organization in 1911 as the sumption. In all instances but one, the company’s first veterinarian and sanitary author has been able to show plant oper­ inspector of dairy farms. In 1927 he was ators that the correct way is the easiest made head of the Sanitation Department. and cheapest way of processing milk and He has been an active member of the As­ will enable him to have peace of mind as sociation, and has rendered substantial w ell as pennies in pocket. help in the establishment of this Journal. 36

Report of Committee On Laboratory Methods A. H. Robertson. Chairman

The Committee on Laboratory Methods, ard buffer solutions, and one the drop was directed at the close of the 1936 ratio method. Four of these laboratories, annual meeting to continue its review of after adjusting the reaction of the media the several modifications of the Babcock vyith the prepared buffer standards, check technique for the rapid approximate the accuracy of the reaction occasionally quantitative determination of fat in frozen by the electrometric method. One lab­ desserts. Conditions did not permit the oratory uses the electrometric method only continuation of this project in 1937 but ; for adjusting the reaction. during 1938 more of the preliminary In the municipal laboratories, a simi­ work will be executed. ' The Kniaseff lar relationship exists among the meth­ method for fat in ice cream (Ice Cream ods used although one laboratory makes Trade journal 30, No. 12, p. 29, Dec. no determination because Standard Meth­ 1934), probably will be included among ods of Milk Analysis, 6th Edition, others to be compared. (American Public Health Association) In the interest of uniformity, three states:— "If the agar is prepared from items pertaining to the agar plate method ingredients specified above (Difco) the of estimating the bacterial content of milk medium will ordinarily have a reaction of and cream will be discussed for the bene­ about pH 6.6. Do not adjust the re­ fit of the Association. action if it is found to fall within the A questionnaire was submitted to sev­ range of pH 6.4 to 7.0.” The college, eral milk /laboratories to discover the and experiment station laboratories are common methods of determining the re­ more prone to vary in their methods of action of culture media and the forms of media reaction adjustment. The drop labeling petri dishes to indicate their di­ ratio method is used in two laboratories. lutions when making standard plate Five laboratories use standard buffer so­ counts by the agar plate method. Replies lutions while six make the adjustment were received from 12 state laboratories, electrometrically either for research work 10 city health departments, and 12 dairy Or to check the reaction by the prepared laboratories at either agricultural experi­ buffer standards. Five laboratories use ment stations or agricultural colleges. the prepared buffer standards. The first question was:—How do you The second question was:—Where a determine’the hydrogen-ion concentration series of different dilutions are used in of your media:-—(1) electrometrically, plating dairy products, what is the simp­ (2) drop ratio method, (3) standard buf­ lest, quickest, and best method of mark­ fer solutions, (4) prepared buffer stand­ ing plates to indicate the dilution used? ards (H ellige, LaMotte, Taylor, etc.) ? The first question , was asked with ex­ Nine of the state health laboratories, seven pectations that one method would be of ,the city laboratories, and five of the ex­ more commonly used than any of the periment station or college laboratories other three. The replies to the second are using one or more of the different question obviously are largely the result types of prepared buffer standards. One of long usage in any particular laboratory. of the twelve state laboratories uses stand- The motive was to find out the method of marking which is least liable to cause Presented before the 26th Annual Meeting. of the confusion. Several suggestions for mark­ International Association of Milk Sanitarians, Louisville, Kentucky, October 11-13, 1937. ing were offered on the questionnaire. Journal of Milk Technology 37

The use of Arabic figures to indicate which appear as brilliant spots or points the sample number over or followed by over a subdued background. The ob­ a variety of combinations of symbols' of server is not blinded by the glare from the Roman style with or without under­ the light source. The counter will ac­ scorings and various alphabetical symbols commodate Wolffheugel, Stewart, or were most common. In a few instances Jeffers guide plates. A centering de­ the Roman style of indicating unit, ten, vice permits perfect centering of the hundred, thousand, ten thousand, hun­ petri dish which is essential with dif­ dred thousand and million was followed ferent styles of guide plates. A 41/2 inch systematically. In other instances, the lens magnifying about iy 2 diameters is use of "Η”, "T”, "MM”, and "B” were mounted above the counter so that it common to indicate dilutions of 1-100, may be raised or lowered for proper fo­ 1-1000, 1-100,000, 1-1,000,000,000 re­ cus. The use of this counter or one spectively. Some laboratories even take giving equivalent results for counting the time to write out the entire dilution colonies is accepted as standard equipment figures in fractions, decimals or ratios. by the Laboratory Section of the Ameri­ Probably no attempt should be made can Public Health Association. to add confusion by suggesting the use A. H. obertson of a different method where any of the R , Chairman. above mentioned systems are well estab­ George E. Bolling lished. The simplest method seems to Η . E. Bowman be that of marking first the sample num­ James P. Buckley ber either over or preceding the dilution R. L. Griffith symbol. The simplest dilution symbol is D. W. H orn the Arabic figure, corresponding to the number of ciphers in the dilution used, C. K. Johns as follows:— If 16 is the sample number, H. W. Leahy then "16-0” is put on the plate with no F. L. Mickle dilution of milk, "16-1” for a 1-10 di­ H oratio N . Parker lution, "16-2” for a 1-100 dilution, Μ. E. Parker ' "16-3” for a 1-1,000 dilution and "16-4” for a 1-10,000 dilution, etc. The above J. Η. Shrader system is offered primarily in the inter­ H. R. Thornton ests of uniformity and simplicity and H . O. W ay probably will find its widest use when F. P. Wilcox establishing new laboratories and when teaching courses in bacteriology. During 1937, attention has been fo­ Cleveland Committee on Arrangements cused on the need for uniform conditions President Tolland has announced the for counting bacterial colonies on the personnel of the Local Committee on Ar­ plates*. Under varying conditions of il­ rangements for the next annual meeting lumination and magnification, the tech­ in Cleveland, as follows: nicians frequently obtained widely dis­ H. O. Way, C hair man ....Cleveland, Ohio crepant counts on the same plate. The R. P. Fowler ...... Oberlin, Ohio result of these observations is the Quebec Charles McDonald ...... Akron, Ohio Colony Counter which has been perfected E. B. Buchanan ...... —Cleveland, Ohio and is now offered for sale**. Both di­ Dr. J. C. W ick h a m ...... Cleveland, Ohio rect and reflected oblique light from a Dr. L. B. Simmons, 60 watt bulb is thrown on the colonies Cleveland Heights, Ohio *Archambault, T., Curot, J. and McCrady, Μ. H. The Need of Uniformity of Conditions for Counting The meetings will be held at the Hotel Plates. (With a Suggestion for a Standard Colony Allerton, and the date is October 19-21, Counter). Am. J. Pub. Health, 27, (1937). *,*Spencer lens Company, Buffalo, N. Y. 1938. 38

An Evaluation of Some of the Testp Used in Detecting Mastitis in Dairy Cattle* A. C. Fay Director of Laboratories, Η. P. Hood & Sons, Inc. Boston, Massachusetts

INTRODUCTION ly normal in health, and the milk may or Definitions. may not be abnormal in appearance. If The term mastitis comes from the the milk is abnormal in appearance, the Greek word "mastos” meaning breast, dairy farmer usually refers to the cow as and the suffix "itis” meaning inflamma­ haying garget. In one dairy section of tion. The several terms which describe Michigan, 88 percent of the herds and 27 the various forms of mastitis may be percent of the cows examined were found classified under the general headings of to have chronic mastitis. The chronic traumatic mastitis and infectious masti­ form of mastitis is. the only-form dis­ tis: cussed in this paper. Traumatic mastitis is inflammation of TESTS FOR MASTITIS the mammary gland resulting from in­ Obviously the first step in the control jury such as a bruise or from prolonged of mastitis in any herd is the detection exposure to cold as may' occur when a of the affected cows. Numerous methods cow lies down on a cold cement floor. for the purpose have been devised, some Traumatic mastitis is usually transitory of which lend themselves readily to field in character, although it may lower the use, whereas others necessitate laboratory local resistance of the gland and thereby facilities. encourage the growth of organisms al­ ready present ifi the tissues. Field Tests. Infectious mastitis is inflammation in­ The methods adaptable to field use are duced by the growth of organisms in the the brom-thymol-blue test, the manual pal­ tissue, and may be either acute or chronic pation of the udder to detect fibrosis or in character. scar tissue, and the observance of abnor­ mal milk which may contain fine flakes Acute mastitis is characterized by in­ detectable only by filtering through a tense local inflammation, little or no se­ fine mesh screen or may be purulent and cretion from the infected quarters, but if secreted, the milk is purulent and coagu- watery in appearance. The brom-thymol- blue test depends upon the fact that milk lable by heat. There is severe toxemia, secreted by the diseased mammary tissue and the cow is febrile and frequently is alkaline in reaction, and the indicator prostrate. Organisms are present but are affords an easy method of demonstrating difficult to isolate and the disease does this fact visibly. The indicator may be not spread in the herd. Fortunately the added directly to the milk, or the milk incidence of the acute form of this disease may be placed on a blotter which con­ is only about 0.8 percent, but unfortun­ tains the indicator. The presence in the ately, most well developed cases of acute udder of fibrosis or consolidated scar mastitis are fatal, Acute mastitis should tissue which can be detected with the not be confused with chronic mastitis. fingers, is a normal body response to ir­ Chronic mastitis, in contrast, is rarely ritation setup by infection. fatal, is very prevalent, the cow is usual­ Laboratory Tests. * Presented before the Massachusetts Milk In­ The laboratory tests may be classified spectors Association, at Worcester, Mass., January 6, 1938. as cultural, chemical, and microscopic ex­ journal of Milk Technology 39

animations. The cultural methods for de­ ent, then make a Breed smear for mi­ tecting mastitis consist of isolating the croscopic examination, The presence or streptococci on special· media usually con­ absence of long-chained streptococci is re­ taining blood, and subsequent identifica­ corded and the number of leucocytes is tion of the isolated strains, and the Hotis interpreted on a basis of an arbitrary stan­ test. The latter method consists of in­ dard of 500,000 per ml. cubating at 37°C. for 48 hours a mixture of 9.5 ml. of milk and 0.5 ml. of a 0.05 THE EVALUATION OF TESTS per cent solution of brom-cresol-purple. In the evaluation of any mastitis test The common mastitis streptococci cause one should regard it from four separate the indicator to turn yellow and the or­ points of view, i.e., ganisms grow as small yellow colonies or 1. How accurate is the test in detecting "buttons” closely adhered to the walls of known positive cases of mastitis? the test tube. 2. How accurate is the test when applied The chemical methods employed in the to known negative cases? laboratory are the examination of milk for 3. What percentage of all positive reac­ chlorides and for the enzyme catalase. tions actually indicate positive cases? The chloride test depends upon the fact that the membrane surrounding the dis­ 4. What percentage of all negative reac­ eased secreting cell loses its normal func­ tions indicate animals which are free tion of allowing certain constituents of from mastitis? the blood to pass through and to restrain These first two questions assume the other constituents. Normally, milk con­ situation in whidh the positive or nega­ tains about 0.14 percent of salts in the tive diagnosis of the disease in the cow form of chlorides. If Chlorides are found is the known factor, and the performance in excess o f this arbitrary maximum, it is of the test is the variable to be measured. assumed that mastitis exists in the udder. On the other hand, under practical con­ The irritation set up t>y mastitis re­ ditions, when the inspector applies the sults in the infiltration of numerous leu­ test to the animals in a herd, the diag­ cocytes and the sloughing of many tissue nosis is the unknown factor and the read­ cells into the milk. These cells, especially ing which he makes of the test is the while still living, secrete the enzyme cata­ only known factor at his command. This lase which breaks down hydrogen per­ presents the other two viewpoints pre­ oxide liberating free oxygen. A test tube sented in the last two questions. containing 15 ml. of milk is filled with For example, if we had a perfect test a dilute solution of hydrogen peroxide and should apply it to 100 cows known to and the tube is fitted with a one-hole rub­ have mastitis and also to 100 cows known ber .stopper containing a capillary tube. to be free from mastitis, we would get When the test tube is inverted, the oxy­ 100 true positive tests and no false nega­ gen liberated from the action of the cata­ tive tests on the positive cows; similarly lase on the hydrogen peroxide collects in on the cows known to be free from mas­ the top. If the amount of gas exceeds titis, we should get 100 true negative 2.5 ml. after 3 hours at 37° C., the milk tests and no false positives. On the other is assumed to be abnormal. hand, suppose that the test were not per­ In the microscopic examination of milk, fect and that in testing 100 cows known an attempt is made to enumerate the to have mastitis, we obtained 75 positive number of leucocytes and to determine readings and 25 negative readings. In the presence or absence of long-chained this case we would have 75 true positives streptococci or other organisms likely to and 25 false negatives. Similarly, if in be the cause of mastitis. The usual pro­ testing 100 cows known to be free from cedure is to incubate the milk for 12 to mastitis we obtained for example 90 nega­ 16 hours at 37°C. in order to favor tive readings, the remaining 10 would be the growth of mastitis streptococci if pres­ false positives. Obviously a given test 40 Tests Used in D etecting Mastitis may be more reliable when applied to readings from the percentage of true positive cows than when applied to cows readings; since there is a chance of mak­ free from mastitis or vice versa. ing 100 true and 100 false readings, the An attempt has been made to express result is divided by 2 in order to return the value of the various tests for mas­ the coefficient to a basis of 100. For titis in the form of a coefficient, and the example, in calculating the percent agree­ data are presented in Table 1. In making ment for detecting mastitis by microscopic the calculations, the successful or unsuc­ examination of a smear from incubated cessful isolation of typical streptococci milk, there were 96 true positive tests on from the milk has been taken as evidence cqws that had mastitis as indicated by the of a positive or negative diagnosis of mas­ isolation of streptococci from their milk, titis. The data are based partly upon and 4 false negative tests which should work recently completed at the Kansas have been positive. Similarly, when ap­ Experiment Station lay the author working plied to 100 cows that did not have mas­ with Professors H. W. Cave and F. W. titis, 91 showed true negative tests where­ Atkeson, and partly upon data published as 9 showed false positive tests. The cal­ in Bulletin 6 2 6 from the New York Ex­ culation of the percent agreement is as periment Station and in Circular 400 from follows: the U. S. Department of Agriculture. 9q true positives plus 91 true For sake of comparison; the relative negatives, minus (4 false neg­ atives plus 9 false positives) 87 per cent values of the tests have been measured by subtracting the percentage of false

TABLE 1 The percent of true and false positive and negative results from various tests for mastitis based upon the isolation of streptococci from the milk as evidence of mastitis. (The data are calculated from results reported from the Kansas and New York Experiment Stations and from the U. S. Department of Agriculture.) Percent of Readings Percent True Percent False Percent Not Confirmed TEST Positives Negatives Positives Negatives Agreement* Positive Negative Streptococci Cultured ...... -.100 100 0 0 100 0 0 Streptococci in smear from incubated milk ...... 96 91 9 · 4 87 8.6 4.2 Hotis test ...... 98 65 35 2 63 26.3 3.0 Leucocytes (500,000 or more) ...... 96 59 41 4 55 30.0 6.3 Fibrosis ...... - 97 43 57 3 ' 40 37.0 6.5 Catalase test ...... - 99 40 60 1 39 37.8 2,4 Chloride test ...... - 95 43 57 5 38 : 37.5 10.4 Brom-thymol-blue test..... 37 99 1 63 36 2.6 39.0 Strip-cup test ...... - 37 89 11 63 26 22.9 41,4 Streptococci in smear from unincubated milk.... 14 100 , 0 86 14 0 45.1 Abnormal milk (purulent or watery) .... 8 100 0 92 8 0 47.9 ^Percent agreement equals the sum of the true positives and true negatives minus the sum of the false positives and false negatives, all divided by 2. Journal of Milk Technology 41

It should be pointed out that the figure however, is discredited by the fact that a showing the percentage agreement is only high percentage of positive cases are not of comparative value, and applies only to detected (false negatives) by these tests. the hypothetical situation in which the In other words, a positive test by any of test is applied to a group of cows half these methods is highly significant but a of which produce milk containing long- negative test gives little assurance that chained streptococci and the other half mastitis does not exist in the udder from produce milk from which these organisms which the milk was taken. It should also could not be isolated. As will be noted be pointed out that these tests rarely give in the table, some of the tests are more a false positive test on cows that do not efficient in detecting negative cases of mas­ have mastitis. titis than in identifying positive cases. Special attention is directed to the If such a test were applied to the cows brom-thymol-blue test and the strip-cup in a herd in which little mastitis existed, test because they are field tests and are so the weakness of the test would not be'· widely employed by inspectors and dairy­ emphasized and the coefficient of agree­ men as a means of segregating the mas­ ment would apparently be high. titis cows in herds. These tests indeed A study of the data in the table brings have value in that they do identify posi­ out the following statements regarding tive cases of mastitis, but their value the value and shortcomings of the various should not be over-estimated by under­ tests for mastitis: estimating their limitations. The fact The microscopic examination of a smear should not be overlooked that these tests from an incubated sample of milk is the fail to point out all of the positive cases most reliable of the simplified tests. This of mastitis in the herd. To the extent method successfully detected 96 percent that the data in the table are applicable of the positive cases of mastitis and failed to generalization, it may be assumed that in only 4 percent. When applied to cows 63 percent of the cases of mastitis will that were free from mastitis, it gave false not be identified by either of these two positive results in 9 percent of the tests. tests. If an inspector applies the brom- The Hotis test is remarkably effective thymol-blue test to the cows in a given in detecting a positive case of mastitis herd, he should recognize two facts, (1) when it exists, (98 percent and failing that the positive tests are true positives in only 2 percent), but unfortunately this and, (2) that the test'has left about two- test gave misleading results when applied thirds of the positive cases of mastitis in to 35 percent of the cows that were free the herd. This is a significant point in from mastitis. This leads to the general a program of control of the spread of statement that a negative test is rarely mastitis in the herd. false but a positive test is frequently ob­ Attention is also called to the increase tained from cases that do not have mas­ in the reliability of the microscopic ex­ titis. amination for streptococci which results The same general statement may be from incubation of the milk for 12-16 made regarding the enumeration of leuco­ hours before preparation of the smear. It cytes, the manual examination of the ud­ appears from, the data at hand that the der for fibrosis, the catalase test, and the microscopic examination of an incubated chloride test. sample of the milk affords the most de­ On the other hand, if a positive test pendable method of identifying the pres­ is obtained by the brom-thymol-blue test, ence of mastitis in a herd. Since the value strip cup test, the microscopic examination of the incubation for a short period (12- of the unincubated smear for streptococci, 16 hours) at 37° C.. depends upon the or if the milk is abnormal in appearance, fact that the mastitis streptococci, if pres­ the odds are quite high that the results of ent, will grow more rapidly than the the tests will be confirmed by isolation of other udder types of bacteria likely to be streptococci. This apparent reliability, present, it is important that the sample be 42 Tests Used in D etecting Mastitis

taken in a sterile container to exclude dependable when applied to contamination from external sources. known positive cases of mastitis and also to milk from cows known su m m a ry to be free from the disease. This paper includes a description of the various types of mastitis and a dis­ (2) The Hotis test, the enumeration cussion of the tests commonly employed of leucocytes, the examination of to identify positive cases of the disease. the udder for fibrosis, the catalase The value of a test must be viewed from test, and the chloride test rarely its performance with milk from cows give a false test on a positive known to have the disease or known to be sample, but milk from one third free from the disease; its value must also, to two thirds of the cows known be interpreted on a basis of the reliability to be free from the disease will of the positive and negative results when give a false positive test. In the diagnosis of the disease in the animal other words, a positive test does is the unknown quantity. not necessarily indicate that the An analysis of data from several sources disease exists. shows the percentage agreement of vari­ (3) The brom-thymol-blue test, the ous tests with the isolation of the strep­ strip-cup test, the microscopic ex­ tococci from the milk. This analysis shows amination of the direct smear for that the percentage agreement of the vari­ streptococci, and the observance of ous tests with the isolation of streptococci purulent, watery abnormal milk is in the following order: are characterized by failing to (1) microscopic examination of a point out a sufficiently high per­ smear from incubated milk 87 per­ centage of the known positive cent, cases to warrant their use as the (2) the Hotis test 63 percent, sole means of identifying mastitis cows for segregation from the (3) enumeration of leucocytes 55 per­ cent, herd. (4) manual palpation of the udder for detecting fibriotic tissue 40 per­ cent, Ernest Kelly Made Assistant Chief (5) the catalase test 39 percent, of Bureau (6) the chloride test 38 percent, Mr. Ernest Kelly, a long-time and ac­ (7) the brom-thymol-blue test 36 per­ tive member of the International Associa­ cent, tion of Milk Sanitarians, has been named (8) the strip-cup test 26 percent, assistant chief of the U. S. Bureau of (9) microscopic examination for strep­ Dairy Industry. He will assist Mr. Reed tococci in the unincubated milk in planning and coordinating the Bureau’s 14 percent, and research work, and in determining its pol­ (10) abnormal (purulent or watery) icies. He will continue, however, to serve milk 8 percent. also as chief of the Division of Market These tests fall into three rather well Milk Investigations. He joined the U. S. defined classes: Department of Agriculture in 1910, and (1) The microscopic examination of has been in charge of the market milk the incubated milk which is fairly problems since 1912. Journal of Milk Technology 43

W hat the Colleges Are Doing in the Training of Milk Sanitarians* j Fordyce Ely Prof essor of Dairy Husbandry, University of Ky., Lexington, Ky.

Excellent work has been accomplished About the same relationship exists be­ throughout the land by milk sanitarians. tween the yes and no response to a ques­ However, only the surface has been tion regarding whether or not new or­ scratched in this field of public service. dinances which have recently been pre­ The next decade will see much progress pared and put into effect conform to the in the hygienic production and distribu­ same code. tion of not only milk but probably also Eleven report that in their opinion, other dairy products. This will be greatly milk ordinances in their states are prop­ beneficial- to the public health as well as erly and adequately enforced and fourteen to a great and constantly changing in­ answered in the negative. Most of these dustry. qualify their answers by indicating that The data contained herein are taken too frequently the principal difficulty is mostly from a questionnaire which was in the smaller population centers. Seven mailed to dairy department heads in land- mentioned poor ordinances or no ordi­ grant agricultural colleges throughout the nances at all were a serious cause of in­ United States. The response came from adequate inspection. Nineteen mentioned thirty-seven States. A n attempt was made definitely that a lack of properly trained to secure an opinion from these men re­ inspectors as well as political interference garding what progress proper milk inspec­ of one kind or another presented a serious tion service was making in their respec­ obstacle to adequately inspected milk sup­ tive states. Professors of agriculture and plies. One asserted that the difficulty was dairying in land-grant colleges have the in failure of the authorities to employ interest of the public as well as the in­ trained inspectors even though plenty dustry and the farmer at heart and offer were available. Presumably this was a a fairly broad view of some phases of description of a type of political pressure the problem as guardians of the public having to do with appointments. Twelve health with especial reference to milk mentioned insufficient funds as at least supplies. partially responsible for a poor milk in­ First, how adequate is milk inspection spection service, and a majority applied service in the various united states in the failure again to the small centers of the opinion of this group of outsiders, as population. The general attitude was far as the actual inspection service is of course one of sympathy and under­ concerned? Twenty-two report that a ma­ standing on the part of dairy department jority of local milk ordinances in opera­ heads throughout the land. There is tion in their states conform in most es­ little the group can do to help you in sentials to the U. S. Public Health Code. solving the problem of political inter­ Ten indicated that such is not the case, ference, but the group can make some and four were non-committal, due to a contribution which may help in provid­ lack of reliable information. ing trained inspectors. About one-third of those reporting * Read before International Association of Milk Sanitarians, October 11, 1937, Louisville, Kentucky. (thirteen) report a substantial demand Training of Milk Sanitakians for men to be employed as milk inspec­ department heads qualified their state­ tors ; five hesitate to refer to the demand ments in answering this question to the for men in this field of work as sub­ effect that they cannot conscientiously stantial but do describe it as an increas­ urge their graduates to enter this field of ing demand; nineteen state that there is work because other lines of work for no substantial demand of which they are whiiph dairy students are trained offer aware; and ten state further that there is more attractive opportunities. One stated no noticeable increase in such a demand that the work in this field lacks a future. for men. These are only expressed opinions. To In response to a question as to how be sure, there exists a limit to the ca­ many four-year graduates who have ma­ pacity of some workers who feel that they jored in some phase of dairy work have should be in positions of more respon­ found employment in milk inspection sibility. Those who have the best interests work during the past five years, the total of tjiis valuable service at heart should do number estimated was about 140 in thirty- thei|· part to develop a personnel service seven states. One hundred of these were which will provide, for less politics in employed as field plant inspectors and appointments and the freer movement of forty as public laboratory technicians. This experienced inspectors to other markets ratio is about what one would expect but into positions commensurate with their the total number employed seems un­ ability. I vividly remember the political deniably low. howl which was heard here in Louisville It is customary for faculty members to when Mr. Jennings came from the great keep rather accurate track o f their gradu­ open spaces of the west to assume the ates for a period of years following leadership of the city milk division. graduation. This fact prompted a ques­ tion, the answer to which has a definite COLLEGIATE INSTRUCTION bearing on the future of the type of Let us now consider specialized courses service which you are attempting to per­ of study which are offered to four-year- fect. The question was: "Do graduates- degree students and which are calculated who go into this field of work tend to to furnish useful background information remain to progress in this work or do for milk sanitarians. The following are they drift from this field into other fields typical of those in colleges of agriculture: o f work” ? In a number o f instances, the Farm Dairying, Dairy Bacteriology, question was not answered for the simple Dairy Chemistry, Market Milk or City reason that in the opinion of the one Milk Supply; the usual sequence of com­ who filled out the questionnaire the pro­ mercial ice cream, butter and cheese mak­ gram on the whole was too new to fur­ ing, and dairy herd management. These nish such information. Twenty states, courses are of course preceded by appro­ however, mentioned a definite drift to priate science prerequisites and are sup­ other fields of work. If 'this is true, plemented by one or more courses in we may conclude that the work furnishes Comparative Physiology and Disease of valuable experience which qualifies men Farm Animals. Opportunity is also given for more remunerative employment in for students to elect other suitable courses other fields. This is not altogther an in Public Health Administration, Hy­ unhealthy situation from the standpoint giene, Water and Food Bacteriology, and of the man but it is a little hard on the many ‘others. However, the student sel­ service to have to replace experienced dom contemplates this field of work be­ men with those of less experience as fre­ fore it is too late to elect a sufficient quently as is described. The answers to number of the courses which would be of this question described a reason for this. most benefit to him. Here again, political pressure on workers An average of about eighteen credits is mentioned and politics entering into is offered in specialized dairy courses in the matter o f salary increases. Three dairy various colleges of agriculture as being Journal of Milk T echnology 45

extremely valuable to one contemplating field of work should be made sufficiently milk sanitation supervision. About 175 attractive to interest four-year graduates students graduate each year who have who major in dairying, veterinary medi­ completed such a sequence of courses. cine, or bacteriology, with carefully chosen During the past five years only about one- electives in the other two. sixth of these have found their way into It was also generally agreed that ex­ your field of work. perience on a farm and in a dairy plant were prime requisites for a young man SHORT COURSES OR CONFERENCES entering this field of work. Several also We are involved in an ever changing mentioned another type of experience, industry. One must be everlastingly alert namely, experience as a milk inspector at to keep pace with the development of least for a few months under the guidance new equipment, new ideas and new dis­ or supervision of a man who is thoroughly coveries in the field of dairying, and their capable of directing a modern program of ramifications into the field of public milk inspection service. There are many health. Thirteen states offer short courses ways to avoid the "policing” aspects of or conferences ranging from two to three milk inspection and substituting therefor days to as many weeks duration. These a type of service which will gain the could be made very useful to milk sani­ confidence and good will of farmer and tarians. A majority of such conferences processor alike. This is much to be pre­ are sponsored or conducted by the dairy ferred to a fear relationship which is departments in colleges of agriculture in rapidly becoming a thing of the past. these thirteen states. The programs of We can furnish you young men with these short courses as a rule make their farm and plant experience, and with a strongest appeal to men of the dairy in­ theoretical background on which to build. dustry who, during the slack season, wish We cannot, however, teach anything to brush up on the newer ideas or qualify which will substitute for the experience for positions of more responsibility. A under fire where the trained but inexperi­ few such conferences are sponsored by enced man can learn to meet the many the universities through their departments trying situations which constantly arise. of hygiene or veterinary medicine. Those The men in charge of the service in key in charge are constantly making an effort markets must accept the responsibility of to feel the pulse of those most interested, and milk sanitarians could definitely in­ furnishing men with this type of experi­ fluence the selection of speakers and the ence in addition to the actual supervision building of the programs to suit the need of the local service. Men with the right if this were made known. background and training will respond In answer to a question as to where in quickly, and a place should be found different states health departments go to for them where this training and experi­ seek men of training as milk inspectors, ence can do the service the most good. their replies were not so encouraging. A Thus the training of milk sanitarians large number described a very nicely who are truly qualified to render an ade­ working relationship with those health quate service is not accomplished by the authorities having to do with locating colleges alone but by the colleges com­ men trained in this field, but invariably bining their efforts with the men actually the answer to this question was: "Inso­ in the service. It is suggested further far as health authorities are permitted by politicians to look anywhere for trained that ways and means be seriously'consid­ men they come to us.” ered of offering a chance for these good In answer to the question as to the type men to keep up-to-date in ideas. The of experience and training which is de­ annual short course or conference for sirable for milk sanitarians, dairy depart­ men actually engaged in the work is a ment heads agreed quite generally. The means to accomplish this end. 46

Abstract of Proceedings of the Twenty-Ninth Annual Meeting of the American Butter Institute November 30 and December I, 1937, Chicago, III. Symposium— The Keeping Quality of Butter At the 29th Annual meeting of the 100° to 120°F. and then draining it. It American Butter Institute held in Chicago, is then filled about one-third to one-half Illinois, on November 30 and December full of water at 170° to 180°F., washing 1, 1937, a symposium on the keeping powder added, and then revolved for quality of butter was held. The sessions at>out 15 minutes in low and then high were well attended by buttermaking sup­ gears, and drained. It is again filled about erintendents, plant operators, agricultural one-half full of water at about 200°F. staff members, and creamery managers. or higher, and revolved for about 20 min­ The subjects discussed were divided into utes, in low then high gears. The butter­ two groups comprising both the microbio­ milk gate must be opened at the start to logical and the chemical changes involved relieve the air pressure. The churn is in the production and distribution of thoroughly drained and finally left with creamery butter. 1 the doors about two-thirds of the way up, HOW TO MAKE THE PLANT SANITARY preferably covered with muslin screens, to The influence of the sanitation of plant dry thoroughly. If prompt cleaning is and equipment upon the keeping quality neglected, it later becomes difficult. The of creamery butter was discussed by Pro­ wpod is seriously damaged if it is left fessor B. W. Hammer of Iowa State Col­ moist over a long period. A musty, sour, lege. He emphasized the great importance or other objectionable odor indicates im­ of physical cleanliness, the necessity for proper care that may be reflected in the bacterial destruction by heat and chemi­ keeping quality of the butter. cal sterilization, and the proper drying of The equipment should be free from fat equipment in the interim between use. or curd. These may be detected by rub­ Proper cleansing involves first the rinsing bing with the hand or a cloth. Microbio­ of the milk solids from the equipment logical examination can be made by sus­ with warm water, then scrubbing it with pending the organisms in water run hot water and washing powder, rinsing through the equipment, and plating them this off with more hot water, and then by standard technique, or by pouring some sterilization with steam or scalding water agar onto the surface and then lifting off adequate in amount to heat all the equip­ the solidified disc and placing it in a ster­ ment thoroughly. The treatment involves ile petri dish for incubation and subse­ the disassembling of all pipe lines and quent colony counting. pumps, their effective cleansing, and also He made the interesting observation that of the vats, coolers and other equip­ that wooden churns have not as yet been ment. satisfactorily replaced by those of metal The churn needs particularly careful at­ construction, and that the hot water treat­ tention. Dr. Hammer stated that to clean ment for cleaning them must be severe the churn, it should first be rinsed by re­ from the standpoint of its effect upon the volving it for several minutes with a gen­ life of the churn if it was to be effective erous amount of water at a temperature of in its sanitary performance. Journal of Milk T echnology 47

In order to locate sources of contamin­ the neutralizer is added after starting to ation in a plant, line run tests are made cool the cream down. Titrations should by examining samples of cream and but­ be made on cooled cream. ter taken at various points during their The fine flavor of butter is largely due progress through the equipment. Yeasts to compounds formed from the citric acid and mold counts show whether these gen­ in milk. About 0.15 percent by weight of eral groups of organisms were picked up citric acid crystals are now added to the in the equipment. Bacterial counts can milk just after adding the mother culture. be made on a differential basis such as This milk is set for 14-16 hours at those which are not butter culture types, 70°-72°F., and the peak of the flavor de­ or counting the lipolytic or proteolytic velopment is reached at an acidity of bacteria. Useful line run tests can also about 0.85-0.95 percent. This gives a be made simply by taking 1 pint samples mild culture flavor. A more highly flav­ of cream in sterile glass jars, churning ored product can be obtained by adding them by hand or in a machine, washing 2 percent of good culture directly to the the butter with sterile water, and holding butter in the churn. portions of the salted and unsalted halves at different temperatures. From time to IMPORTANCE OF PROPER PASTEURIZ­ time these are examined for defects. ATION He pointed out especially the need for The development and function of pas­ testing the water to ascertain its freedom teurization as a unit operation was dis­ from disease germs as well as those types cussed by Μ. E. Parker, Manager of Pro­ of organisms which impair butter quality. duction of the Beatrice Creamery Co. Its effect on the butter can be determined Cream is pasteurized by indirect heat ex­ by washing small experimental churnings change through metal walls, preferably with untreated water and also with water when the heating medium is only a few that has been boiled and cooled. degrees higher than the cream, or by di­ rect heating by mixing steam into the RELATION OF ACIDITY TO FLAVOR cream under high pressure at 230o-300° The importance of churning acidity and F. and suddenly expanding the mixture its proper control was presented in a pa­ into a high vacuum, thereby exposing the per by Dr. N. E. Fabricius, also of Iowa cream to the high temperature for Only a State College. He was one of the two few seconds at the most and then almost American buttermakers who received a instantly cooling it by the expansion. perfect score at the World’s Dairy Con­ However, common practise in the treat­ gress in Germany last year. Defects as­ ment of cream is to use two flash pas­ sociated with too high churning acidity teurizers in series, the first to boost the are sour, metallic, oily, and fishy flavors, temperature of the cream, and the second whereas too low an acidity leads to putrid, to finish it off. About 30 seconds is re­ cheesy, and surface taints. Improper ad­ quired to heat the cream from 100° to dition and treatment with the neutralizer 180°F. The distance of travel from the may impart a burned neutralizer flavor, heater to the cooler keeps the cream at the a scorched, cooked, oily, or a soapy flavor. high temperature for variable lengths of In general, the limes (calcium oxide and time according to the setup. Therefore, magnesium oxide) in 10-15 percent so­ flash pasteurization is not an instantaneous lution are the most desirable cream neu­ operation but should be recognized as tralizers. At least 20 minutes should high-temperature, short-hold pasteuriza­ elapse between the time the lime is added tion. Some preliminary laboratory experi­ and the heat is applied. The temperature ments showed that at pasteurization tem­ should not be higher than 80 °F. It is peratures of 175°-190°F., about one-third important that only enough neutralizer be of the surviving bacteria were proteolytic added before pasteurization to reduce the types, and at 195o-205°F., these consti­ acidity to 0.25 percent, and the rest of tuted about two-thirds of the microbic 48 Abstract of Proceedings, American Butter Institute population. He pointed out the lack of of the body of butter is largely determined detailed information as to the types of by the proportion of fat of low solidify­ surviving organisms and the need for re­ ing point, and this is controlled by the search to determine definitely the effect of temperature and method Of cooling the pasteurization on the bio-chemistry and oqeam, the churning temperature, and the microbiology of cream and their effect on temperature of the wash water. Harder the finished butter. butter is produced by lowering the tem­ perature of churning and by cooling the COOLING, CHURNING, AND WORKMAN­ crpam over a surface cooler instead of in SHIP a vat. Also, the lower the temperature Dr. O. F. Hunziker in charge of manu­ of the wash water, the softer the butter. facture of the Blue Valley Creamery Co. For churning from winter cream, the discussed the factors between the pasteur­ cream should not be excessively cooled izer and the churn as well as the work­ bttt only to or slightly below the churn­ manship as affecting good keeping and ing temperature, and the butter should eating qualities. Oily-metallic flavor de­ be washed with water at a temperature of velops in butter made from farm-skim­ 4Ci°:-50oF. or lower. For churning sum­ med, sour, neutralized cream, especially mer cream with its softer fats, the cream when abnormally rich in butterfat. It ap­ should be cooled to, and held and churn­ pears in the fresh butter at the churn. It ed at temperatures as low as- practical, is chemical in nature and is caused by and the butter should be washed wih high acid cream, high fat content (over water at a temperature no higher than 33 percent), flash pasteurization at 180° that of the buttermilk and preferably sev­ F, or higher (preferably 165° F. for 30 eral degrees colder. minutes), prolonged holding after pas­ teurization or for over 6 hours after cool­ THE ADDITION OF FLAVOR ing before churning, and the presence of The addition of starter distillate to but­ metallic salts such as exposure to rusty ter was described by Dr. H. A. Ruehe cans and copper plant equipment. Over­ of the University of Illinois as contribut­ working lowers the aroma and quality of ing materially to the improvement of the good butter and covers up to some ex­ flavor. When 1 part of diacetyl was add­ tent the defects of inferior butter. Over­ ed to 800,000 parts of butter (0.00012 washing not only leaches out much of the percent), the latter scored higher than desirable aroma but also , removes the lac­ the control after being held for 6 months tic acid and its salts apd lactic bacteria, at -10 °F, storage. Butter containing add­ all of which help to hold in check the ed distillate also possessed a better keep­ development of putrefactive types of or­ ing quality. A rapid method to determine ganisms. Excessive washing also removes the diacetyl volumetrically has recently the protective films of protein and sugar been worked out. It depends on the oxi­ from the fat and exposes it to oxidation. dation by hydrogen peroxide of diacetyl On the other hand, heavy washing may to two molecules of acetic acid. The ace­ be favorable for butter from cream of tic acid is then titrated directly. Acetyl- poor quality. Polluted water may cause methylcafbinol can be determined at the objectionable flavors. same time if it is first oxidized to di­ acetyl. ; THE BODY OF BUTTER The structure of butter was described CHEMICAL. CHANGES ASSOCIATED WITH by Dr, S. T. Coulter of the University of DETERIORATION Minnesota as consisting of granules of A close correlation was shown by Dr. free fat in which is dispersed other fat G. E. Holm of the U. S. Bureau of Dairy retained in what is left of the original fat Industry to exist between the loss of score globules as they occurred in cream, and. and the development of peroxides. But­ also droplets of buttermilk. The texture ters churned from cream of relatively low Journal of Milk T echnology 4 9 acidities (below 0.20 percent as lactic counts do not necessarily mean that the acid) were found to 'be superior in keep­ possibilities of deterioration are great. ing quality to those made from cream of Organisms of the coli-aerogenes group higher churning acidities (0.30 percent may cause flavor defects in butter. They or more). Apparently a measure of the tend to follow the numbers of yeasts and rate of oxidation of its butterfat will pro­ molds, and indicate contamination, al­ vide a reliable index of the rate of de­ though they are not significant to indicate terioration of a butter. the keeping quality of butter. Prelim- , inary work indicates that the new phos­ MICROBIOLOGICAL EXAMINATION phatase (monophosphoesterase) test is ap­ The various microbiological methods plicable to butter to determine whether it for the examination of butter were dis­ was made from properly pasteurized cussed by Dr. E. H. Parfitt of Purdue cream. University. The yeasts and mold count of butter is comparable to the total bac­ PRACTICAL TEST OF KEEPING QUALITY teria count of milk Rs a measure of its A new practical test was described by sanitary quality and the conditions under C. H. Parsons of the chemical laboratory which butter is made. In general, a of Swift and Company for the measure­ high yeast and mold count indicates that ment of the keeping quality of butter. A conditions exist which may be detrimental research of six years duration in which to good keeping quality. The direct mi­ many thousands of samples of butter croscopic count is useful to forecast the have been constantly assayed, has fully keeping quality of sweet cream butter demonstrated that the holding of butter containing a low percentage of salt but is for 14 days at 60°F. gives excellent in­ not so dependable for salted butter. formation as to its keeping quality as well When applied to salted butter made from as any outstanding flavor, defects. The sour cream, it is useful to determine butter is first held overnight at a tem­ whether the lowering of the score of the perature of 45° to 50°F. The following butter during storage was caused by mi­ morning it is scored for quality. Then it croorganisms. A new microscopic method is transferred to an incubator at 60°F. has been developed within the past year where is is held for 14 days. It is trans­ to detect whether butter is made from ferred to a 45°-50°F. room, held over­ cream containing excessive amounts of night, and again scored by the same judge. mold. There appears as yet no relation The degree of keeping quality is propor­ between the frequency of distribution of tional directly to the loss in score. Sim­ mold mycelia and keeping quality. Dif­ ilar but less informative results are ob­ ferential techniques have been developed tained by holding at 68°-70°F. for 7 to determine the proteolytic and lipolytic days. bacteria in butter. In general, low counts Μ. E. Parker of these types are desirable but high J. H. Shrader

NEXT ANNUAL MEETING The Twenty-seventh Annual Meeting of the International Association of Milk Sanitarians wijl be held in Cleveland, Ohio, October 19, 20 and 21, 1938, with headquarters at The AHerton. 50

Research with Cream at the Massachusetts State College* Merrill J. Mack Comparatively little research has been milk and bottle it with no further treat­ conducted on cream and on the many ment. problems arising in marketing it. A real 2. Standardize it with their own cream and need for research on this dairy product is pasteurize all of it together. r quite evident. 3. If coffee cream, standardize, pasteurize, DESIRABLE CHARACTERISTICS OF CREAM and homogenize the product. Good cream should possess these characteris­ Jn recent years buyers of cream in New tics: England have placed considerable stress 1. A clean and pleasant flavor. on the matter of oiling off. For this rea­ 2. Excellent keeping quality. son Mr. Herbert Jenkins of New England 3. Good color and "high coloring ability” Dairies was glad to cooperate with me on in coffee. this problem. 4. High viscosity. At the beginning of the study, the need 5. Absence of cream plug. for a test for "oiling off” of cream was 6. Absence of serum separation or "cream apparent. For research purposes, mere line”. observation of the cream when added to 1. Absence of "oiling off” in coffee. hot water or coffee was not exact enough. 8. If whipping cream, good whipping prop­ The test used by us is given in our erty, and a finished whipped cream of article in the November, 1937, issue of Stiff consistency, high overrun, and ab­ the Journal of Dairy Science. It simply sence of serum drainage. consisted of centrifuging 1 cc. of cream At the Massachusetts State College we in μ skim milk test bottle under such con­ have been concerned with two of the ditions that the large droplets of fat above factors, namely, (1) the extent of which would normally separate out in oiling off of cream when used in coffee, coffee would be separated out in the and (2) the factors affecting whipping graduated neck of the test bottle. The creain and the characteristics of the fin­ test must be considered as a qualitative ished product. test, though it did give sufficiently ac­ Our publications on these subjects will curate results for research purposes. We be sent to any one requesting them. recprded the divisions on the test bottle as round numbers, any reading above 1 OILING OFF OF CREAM IN COFFEE producing enough oil to be noticed on the In our principal New England cities, surface of a cup of coffee. a somewhat unique situation exists in that In running the test, quick pipetting afr many milk distributors skim but a small ter thorough mixing is essential, other­ portion of the cream they sell. This is wise the large oil drops will rise in the particularly true of the smaller companies. warm test sample and a representative A few creamery companies distribute a sample will not be secured. large share of the cream, skimmed in The test evidently has other uses. In northern New England and sold in can one dairy company it has been used in a lots to the milk distributors. study of fat losses at heating surfaces The milk distributors differ in their in preheaters, vats, etc. Dr. Keenan of treatment of this cream. Some of them— the Whiting Milk Company has used the 1. Standardize it cold with milk or skim test in studying the effect on oiling off of coffee cream by such treatments as the * Presented before the Metropolitan Dairy Tech­ nology Society, New York City, February 23, 1938, Dahlberg process for heat treating cream. Journal of Milk T echnology 51

Factors causing oiling and its preven­ cream if freezing on the cooler later were tion: prevented. 1. Partial freezing of milk before separa­ 11. Storage in the home refrigerator did not tion will increase the oiling tendency of the increase the tendency to oil off. cream. 12. Some restaurant cream dispensors were 2. As separating temperatures are increased found to break the fat emulsion and cause bad above 90° F., the fat emulsion becomes in­ oiling off. creasingly less stable. 3. The temperature of cream when stan­ WHIPPING PROPERTY OF CREAM dardized and whether standardized with skim Much of the published research con­ or whole milk makes no difference. Neither cerning whipping cream was done with does the time or temperature of standardiz­ hand operated whippers. These results ing make any significant difference. may be open to question because of the 4. Filling vat direct from separator. Ap­ lack of sensitivity of the method. plying heat slowly as vat fills is a satisfactory In our studies an electric whipper was procedure. Also have cooling medium flow used and the rate of whipping was se­ through vat jacket but no agitation is satis­ cured by recording the input in watts factory. Never heat and hold at near the necessary to run the whipper. This prov­ pasteurization temperature while vat fills. ed to be a satisfactory method of com­ 5. Pasteurization: (a) prolonged holding paring different creams. (40 min.) at the pasteurization temperature in­ Especially desirable properties of whip­ creased the amount of oiling, (b) partial filling ping cream have been enumerated as: of vats also proved harmful to the fat emul­ high viscosity, good whipping ability, sion, (c) type of vat. The coil vat and fast stiff-whip, high overrun, absence of serum propellor agitator both were unsatisfactory. drainage. A number of factors affect Paddle agitation and slow propellor agitation these properties and will be discussed in both proved satisfactory, (d) Heating to a detail. temperature above 145 °F. increased the amount When whipping cream, trouble is often of oiling off. (e) A heating medium above due to— 160° also caused trouble. a. Over-full bowl. Whipping will not oc­ 6. Pumping cream by proper sized pumps cur if whipper is submerged. did not increase the tendency to oil while the b. Temperature. Temperature above 40° F. use of over-size pumps did. Steam piston progressively lowers whipping ability, re­ pumps do not affect the fat emulsion ad­ duces stiffness and overrun, and increases versely; in fact with cream that oiled badly, serum drainage. Precaution: Use cold piston pumps actually re-emulsified some fat cream and cold utensils. and improved it slightly. 7. Cooling in the vat increased the ten­ Considerations for dairyman. dency to oil off considerably. Cooling over 1. Fat test. 30 to 35 percent fat most the surface cooler had no effect unless freez­ desirable. Low fat cream is low in vis­ ing of cream to the cooler occurred. This cosity, whips slowly to soft product. was found to be a serious cause of oiling off Cream higher than 35 percent fat pro­ in retail coffee cream. duces no serum drainage but a soggy 8. Aging cream at low temperature had no product with low overrun. Great danger effect on the stability of the emulsion. of churning. 9. Shipment had no effect if the cream 2. Separating temperature. Low separating was cold and cans were full enough to pre­ temperature desirable. 90° F. proved vent churning. superior to 100° F. because cream was 10. Homogenization completely stabilized more viscous, had less drainage and the emulsion and prevented-, oily separation, gave a stiffer whip and whipped easier. 300 lbs. pressure being sufficient. The colloid 3. Pasteurizing temperature. A pasteuriz­ mill and hand homogenizer were ineffective. ing temperature of about 155° F. pre­ No trouble was experienced with homogenized vents serum separation, lowers bacteria 52 Research with Cream

counts, imparts good keeping quality, ing the sugar any time after the first lowers serum drainage from whipped minute of whipping causes no difficulty cream, and does not affect adversely in whipping or in any other respect. other properties of whipped cream. 10. Effect of homogenization. Homogeni­ 4. Standardization methods. Standardiza­ zation at 300 lbs. or higher reduces tion with whole or skim milk, either whipping ability, and increases serum before or after pasteurization, appeared drainage and fat loss in the drain. Very to be of little consequence. Standardi­ low homogenization pressures of 50 to zation prior to pasteurization recom­ 100 pounds at low temperatures are mended because bacterial contamination said to increase viscosity without no-r was less likely to occur. . ticeably decreasing whipping ability. It also prevents - serum separation in the 5. Temperature treatment during cooling. bottled Cream. This cannot be done Delayed cooling, according to the Dahl- with an ordinary homogenizer because berg process, is said to increase the gages do not register these low pres­ viscosity of cream. If you practice this sures. method of cooling and find it beneficial 11. Effect of freezing milk or cream. Par­ to viscosity, the practice should be con­ tial freezing (13 percent) of milk prior tinued. Our experiments indicate that to separation did not seem to decrease this method of cooling, however, does whipping ability. Freezing of cream be­ not improve whipping properties of fore pasteurization lowered whipping cream or benefit the finished- product. ability but freezing of cream during 6. Increasing serum . solids content' of delivery had very little effect on whip­ cream. This practice is followed by some ping ability. However, such creams ex­ dairymen as a means of increasing the hibit “cream plug” and oil off in coffee. body of cream. We found it to be of 12. Feed of cow. The source of protein, no value in that it did not improve whether animal or vegetable, made no whipping properties or reduce serum difference in the whipping properties of drainage. Not worth the added trouble cream. England (Maryland) reports and expense. that the breed of cow" does make a 7. Aging time. Aging cream longer than difference, Guernsey cream whipping 30 24 - hours is of no practical advantage percent faster than Ayrshire cream. Eng­ so far as whipping ability-is concerned. land also reports that the air whip is 8. Addition of stabilizer. This is clearly preferable to the turbine type of whip­ an infraction of most state regulations. pet for the commercial production of Yet the practice of adding gelatin, Dari- whipped cream. (Bui. 393, Maryland loid, or some other stabilizer is con- Agr. Expt. Sta.) ‘ tinued by some companies. The addi­ 13. Increasing the acidity of cream does not tion of· a stabilizer benefits some prop­ affect the whipping properties unless erties and injures others. Dariloid and the cream is sour. The poor whipping gelatin are the most desirable particu­ of cream in the late winter can be cor­ larly Dariloid because so small an rected by the addition of 0.1 percent amount is needed. As little as 0.1 per­ sodium citrate :(Sommer), This does cent increases cream viscosity noticeably not affect flavor of the whipping cream. and lowers the amount of serum drain­ In conclusion, it·should be stated that, age. In general, stabilizers lower whip­ in general, defects in cream are ' due to ping ability and overrun. excessive agitation in processing, too rap­ 9. Effect of adding sugar. About 10 per­ id heating, or reprocessing, if cream is cent by weight of sugar is desirable in handled a minimum number of times, whipped:· cream. This, should not be carefully pasteurized and cooled, and added to cream before whipping be­ marketed when fresh, little difficulty cause this lowers whipping ability. Add­ should be encountered with the product. 53

JOURNAL OF MILK TECHNOLOGY

• Official Publication of the

International Association of Milk Sanitarians

Editors

W. B. Palmer, Managing Editor J. H. Shrader, Editor Orange, N. J. East Orange, N. J.

Associate Editors

C. A. A bele Ernest K elley Montgomery, Ala. Washington, D. C.

Sarah V ance D ugan P. F. Krueger Louisville, Ky. Chicago, 111.

J. G. H ardenbergh Η. N. Parker Plainsboro, N. J. Jacksonville, Fla. M. A. H einzm an Μ. E. Parker Ventura, Cal. Chicago, 111.

J. A. K een an G. C. Putnam . Boston, Mass. Chicago, 111.

C. K. Johns H. R. Thornton ■ Ottawa, Canada. Edmonton, Alberta, Canada

1 The JOURNAL OF MILK TECHNOLOGY is issued bimonthly beginning with the Janu­ ary number. Each volume comprises six numbers. Subscriptions: The subscription rate is $5.00 per volume. Advertising: All correspondence concerning advertising, reprints, subscriptions, and all other business matters should be addressed to the Managing Editor, W. B. Palmer, 29 North Day Street, Orange, N. J. Manuscripts: ..fill correspondence regarding manuscripts, editorials, news items, announce­ ments, and other reading material should be addressed to the Editor, J. H. Shrader, 339 Spring- dale Avenue, East Orange, N· J. Membership and Dues: Active and Associate Memberships in the Association are $5.00 per year. This indudes all issues of the-Journal. All correspondence concerning membership in the ASSOCIATION OF JdILK SANITARIANS, including applications for membership, re­ mittances for dues, failure to receive copies of the JOURNAL OF MILK TECHNOLOGY, and other such matters should be addressed 'to the Secretary of the Association, C. Sidney Leete, State Department of Health, Albany, Sli Y.?1 S# '·. 54 A pplication for Membership

Application for Membership I wish to apply for membership in the International Association of Milk Sani­ tarians.

...... ,...... 19......

Name —...... —- ...... (Print name in full and degree)

Address...... ,...... ~ (Street and City)

Present occupation ......

Previous positions

Application is for:

...... Active membership

...... Associate membership Applicant may qualify for MEMBER if officially engaged in dairy or milk inspection, or laboratory control, or administration of such function for any country or subdivision thereof; or officially engaged in research or educational work related to dairy or milk inspection for any country or subdivision thereof. ASSOCIATE MEMBER if interested in the promotion of dairy sanitation. DUES: $5.00 per year payable in advance, and includes the Association JOURNAL OF MILK TECHNOLOGY. Application endorsed by: I Active or ...... ? Associate >T \ Members

Mail with remittance to: C. Sidney Leete, Secretary, Int. Assn, of Milk Sanitarians, N, Y. State Dept, of Health, Albany, N. Y. Journal of Milk T echnology 55

INTERNATIONAL ASSOCIATION OF MILK SANITARIANS

CONSTITUTION

Adopted October 16, 1911*

NAME This Association shall be known as the International Association of Milk Sanitarians.

OBJECT The object of this Association shall be to develop uniform and efficient inspection of dairy farms, milk establishments, milk and milk products, and to place the inspection of the same in the hands of men who have a thorough knowledge of dairy work.

MEMBERSHIP There shall be two classes of membership in this association: Active and Associate. The active membership shall be composed of persons who are officially engaged in dairy or milk inspection, or the laboratory control of, or the administration of such function for any country or any subdivision thereof, and of persons who are officially engaged in research or edu­ cational work related to dairy or milk inspection for any country or subdivision thereof, provided, however, that all persons who at the time of the adoption of this amendment are members of the Association, shall be active members. The associate membership shall be composed of any persons not eligible for active member­ ship, who are interested in the promotion of dairy sanitation. Associate members shall not be eligible to vote, serve as officers, hold the chairmanship of any committee, serve on the Resolu­ tions Committee, or serve as majority members of any committee of this Association. Any properly qualified person may make application for active or associate membership to the Secretary-Treasurer and if application is accepted by the Membership Committee, said appli­ cant may become an active or associate member, as the case may be, upon payment of the annual dues of five dollars ($5.00). OFFICERS The officers of this Association shall be a President, three Vice-Presidents, a Secretary- Treasurer, and two Auditors, who shall be elected by a majority ballot at the Annual. Meeting of the Association, and shall hold office for one year or until their successors are elected. An Executive Board, which shall direct the affairs of the Association when not in Annual Session shall consist of the President, the three Vice-Presidents, and the Secretary-Treasurer. 56 Constitution

AMENDMENTS This Constitution may be amended by atwo-thirds affirmative vote of those active members of the Association who register their votes with the Secretary. Any member proposing amend­ ments must submit the same in writing to the Secretary-Treasurer at least sixty days before the date of the Annual Meeting, and the Secretary-Treasurer shall at once notify all members that the proposed amendments will be open for discussion at the Annual Meeting immediately succeed­ ing such notification. After discussion at the Annual fleeting such Amendments, upon a majority affirmative vote of the members in attendance shall be, within 90 days, submitted to the entire membership of the Association by the Secretary-Treasjirer. All members voting on such amend­ ments shall, within 60 days after receipt of such notification, register their vote in writing with the Secretary-Treasurer on blanks furnished by the Association. These ballots shall be opened and recorded by the Executive Committee, and the results shall be reported by the Secretary- Treasurer at the next Annual Meeting: and if the amendments are passed they shall become a part of the Constitution from the date of such report by the Secretary-Treasurer at the Annual Meeting.

* Amended October 20, 1932 and October 15, 1936.

WHAT ARE THE ANSWERS?

Is there a relation between mastitis and Bang's dis­ ease? How useful are platform tests? How do bacteria counts run in a city ice cream supply? W hat are the weaknesses in heat-regenerator set­ ups? How can washing and sterilizing performance be made dependable?

Read the July issue Advertisements VII

Borden’s Offer 2 Kinds of Vitamin D Milk IRRADIATED VITAMIN D MILK A 135 Unit Vitamin D Milk that is used in thousands of homes today. 135 U.S.P. XI units of Vitamin D in every quart. A safe and dependable source of the "Sunshine” vitamin for the entire family. 400 UNIT VITAMIN D MILK A "400” unit Vitamin D. Milk for babies under 2 years and special cases where the physician believes an extra measure of vitamin protection to be desirable. This milk is prepared with IRRADIATED ergosterol, and contains 400 U.S.P. XI units of Vitamin D per quart. Both Borden’s 400 unit Vitamin D Milk and Borden’s IRRADIATED Vitamin D Milk have been accepted by the Council on Foods of the American Medical Association. CONSULT YOUR PHYSICIAN AND DENTIST ABOUT YOUR DIET

Look the World Over! ...... And you find outstanding dairy plants in the leading milk pro· ducing countries using wyandotte Specialized Cleaners and Alkalies. "Wyandotte" aids dairy operators "the world around." Profitable Plant Cleaning Your Dealer will supply Wyandotte "Cleaner and Cleanser"—"Poma" Cleaner—or "Cherokee"—as indi­ cated by the analysis of your local water supply. Every one assures quick, thorough cleaning with strict economy. Safe and Sure Sterilizing Dissolve "Steri-Chlor" (powder) in water and have clear sterilizing solu­ tion of any desired strength. Ready for instant use. Does not corrode metal. Convenient—Economical.

The J. B. Ford Company Wyandotte, Michigan

When writing to advertisers, say you saw it in this Journal. VIII Advertisements

JWJ ■Vv·

Index to Advertisers

PAGE NO,

Aluminum Seal Company ...... IV

Borden...... VII

Cherry-Burrell Corporation...... VI YOU CAN’T KILL WITH Creamery Package Company...... V A POP GUN! P L A Y IN G "cops and robbers" makes an ear- Difco Laboratories...... Back Cover ■ splitting din . . . but it's harmless. A steam line also makes a deafening roar . . . but it too, Diversey Corporation — ..... VIII is harmless. Heat . . . not noise . . . will kill bacteria. Unless equipment is heated to at least 180° F. for fully 2 minutes, it amounts to just Ford Co., The J. B...... !...... VII another game of make-believe. W hy play games with bacteria? Diversol kills bacteria quickly and Sealtest, Inc...... IX surely at any temper­ MAKE TH IS T E S T ature. Easy to use. Unlike ordinary ster­ Standard Cap and Seal Corp. II S • T MOS’ZI.C ilizers, Diversol never corrodes or damages Vitex Laboratories ..... Ill equipment. W on't lose its strength. Want facts? Write today for Research Bulletin on the rela­ tive efficiency of heat versus chlorine Place a thermometer at sterilization. ‘ varying distances from the steam hose nozzle. THE DIVERSEY See how quickly temp­ erature drops below CORPORATION mini mum 53 W. Jackson Blvd., necessary to Chicago, III. kill bacteria.

KILLS BACTERIA IN COLD WATER When writing to advertisers, say you saw it in this Journal. Advertisements IX

"VITALLY NECESSARY" Sealtest has come a long way since its incep­ tion three years ago. And, of course, much of its progress has been due to the fine co-opera­ tion of Milk Supervisors with Sealtest Repre­ sentatives, throughout the country . This Lab­ oratory System of over 100 chemical and bac­ teriological laboratories, several hundred tech­ nicians, headed by some of America's foremost food scientists—this System has yet many mile­ stones to reach and pass. And, in the attain­ ment of these goals, the help and understand­ ing of Milk Supervisors will be vitally necessary.

SEALTEST, INC., 120 Broadway, New York

When writing to advertisers, say you saw it in this Journal. CENTER FOR RESEARCH LIBRARIES

COLI IN MILK

BACTO-BRILLIANT GREEN BILE 2% Bacto-Brilliant Green Bile 2% is recom­ mended for the detection of coliform bacteria in milk. When this product is prepared for use, it conforms in every way to the medium specified for this purpose in "Standard Methods of Milk Analysis” of the American Public Health Asso­ ciation. Results obtained by direct inoculation of the milk sample into fermentation tubes of medium prepared from Bacto-Brilliant Green Bile 2% are reliably accurate and require no further confirmation. Production of gas in this medium is an indication of the presence of coliform organisms in the milk. Bacto-Brilliant Green Bile 2% is readily made up for use. It is completely soluble in water and requires no adjustment of its reac­ tion. After autoclave sterilization the medium has a reaction of pH 6.8.

Specify “DIFCO” THE TRADE NAME OF THE PIONEERS In die Research and Development of Bacto-Peptone and Dehydrated Culture Media

DIFCO LABORATORIES INCORPORATED DETROIT, MICHIGAN

Printed in U. S. A.