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A Glass Milk Bottle with Narrow Pouring Lip and Minimum Drip* Lloyd Arnold, M. D.
University of Illinois College of Medicine, Department of Bacteriology and Downloaded from http://meridian.allenpress.com/jfp/article-pdf/1/6/5/2392644/0022-2747_1_6_5.pdf by guest on 28 September 2021 Public Health, Chicago, III.
Considerable confusion has existed in tie of milk. It was necessary to define the rules of various public health agencies the area of the bottle to be covered or regarding the methods of enclosing the protected by a- cap. We began our study milk in a glass bottle. A review of this by pouring milk from bottles by hand, subject showed that there had been little and observing the behavior of the milk as scientific work done upon which to base it was pouring out of the bottle and over enforcing regulations to protect milk the lip. We were convinced that this properly. We undertook such a study method was unscientific, uncontrollable, in this laboratory. and variable. It was impossible to dupli Dearstyne and Ewing (1920) studied cate the same identical conditions. We the bacterial flora on the lips of milk then designed a pouring machine to al bottles. They found that some bottles low us to pour milk from several bottles of pasteurized milk, enclosed with flat of different design at the same time under disc caps, had 100,000 to 200,000 viable identically the same conditions. The ma bacteria on the lip. They concluded that chine used for the major part of this work the bacteria deposited on the lip and cap is shown in Figures 1 and 2. were probably more dangerous than the We observed early in our work that the bacteria in the milk inside the bottle. angle to which the bottle was rotated ex Jackley (1922) called attention to the ercised considerable influence upon the seriousness of lip contamination, because behavior of the milk as it passed over the the poured , milk contained these bacteria pouring lip. The first glass of milk is as well as the cap which acted as a bac delivered from a full quart when the bot terial reservoir to contaminate the milk tle is rotated from the upright or 0° to continuously. the 78° angle, and held in this position Rice et al. (1924) studied the bacterial as long as the milk flows out of the flora in and on paper caps. Isaacs and bottle; the next glass of milk is delivered Zeiben (1932) recorded the bacterial when the bottle is rotated from 78° to counts in milk capped with discs and 84°. Table 1 gives in exact form the hoods. They showed the former did not results of one hundred pouring experi protect the milk as efficiently as the com ments. It was found that when the full plete coverage afforded by the hood. quart of milk was rotated from 0° to 78°, Sansby and Halvorson (1936) described there was more surface area of the glass a new type of bottle neck design to pro contacted by the milk than at any other tect the pouring lip with a relatively small angle. There was more drip at the 78° metal cap. angle than at any other. Angles greater than 90° do not present pouring lip prob STANDARD POURING MACHINE lems because the milk does not have an We began this study with the objective opportunity of contacting the lip in the of trying to ascertain the most suitable same manner. Hence, we chose the 0° type of cap to use to enclose a glass bot- to 78° angle, or the first glass of milk pouring from a quart bottle as the best *Aided b y a grant from the Associated Milk Dealers Inc. of Chicago. . single pour to define the pouring lip. Lip Contamination of M ilk Bottles Downloaded from http://meridian.allenpress.com/jfp/article-pdf/1/6/5/2392644/0022-2747_1_6_5.pdf by guest on 28 September 2021
Figure 1. This shows the stand ard pouring machine in an upright position ready to be loaded with six bottles for testing.
Figure 2. This shows the stand ard pouring machine tilted to '78° angle and held in this po sition until one glass of milk is delivered from the bottle. Journal of Milk Technology 7
MEASUREMENT OF LIP CONTAMINATION could not be used. We finally used a Our next problem was to find an in twenty-four hour old broth culture and dicator to use to aid us in determining the applied this to the glass without dilution. exact area of the glass of the bottle adja The seeding was so heavy and the bac cent to the opening contacted by the milk terial population so dense that even if during pouring. It is possible roughly fifty percent or more died, there were to evaluate or classify bottles by observ still several thousand (10,000 to 50,000) ing, with the eye, the stream poured and on the lip even after twenty-foijr hours. Downloaded from http://meridian.allenpress.com/jfp/article-pdf/1/6/5/2392644/0022-2747_1_6_5.pdf by guest on 28 September 2021 the drip, but this is not accurate and is Small tightly wound cotton swabs were only useful for orientation purposes. We sterilized and dipped into a twenty-four tried to use dyes and stains, biit so far hour broth culture of B. prodigiosus. The this has not proved successful. We had excess fluid was pressed out by rotating to use living bacteria applied to the glass the swab against the inside wall of the test surface as our indicator of the area of tube which contained the culture. This the glass contacted or covered with milk swab was used to inoculate or mark the during pouring. surface of the upper end of the glass bot Some investigators have used quantita tle over which the milk was to be poured. tive methods in determining the bacteria The outside of the pouring lip including washed off from the pouring lip of milk the upper part of the neck of the bottle bottles. We were unable to do this. If was divided into horizontal, concentric bacteria are suspended or diluted in water anular zones from the top downwards. or saline, and applied to a clean glass Each anular zone was usually approxi surface, the death rate is high because mately 14 inch. If for instance, six of the dessication factor. The number zones were to be studied, six bottles of of living bacteria decreases with time. the same type were washed, rinsed, cov Therefore, counting the bacteria in the ered with a paper extending down over milk after it has passed over such a seeded two-thirds of the bottle, and tied with, a surface would be variable unless corre strong string. The bottles were then lated with the time of sojourn of the autoclaved at 15 pounds pressure for 35 bacterial population on the glass surface. minutes. These bottles were then put in We used bacterial suspensions 1:100, the dry air sterilizer to dry the paper and 1:250, 1:400, 1:750 and 1:1000, and bottles. The paper wrapping was re found none of these satisfactory because moved, and the sterile bottle was handled of the high death rates of the bacteria on by holding it below the upper third. It the glass surface. Bacteria.were suspended was immediately filled with fresh fluid in egg white, gum acacia, milk, and other grade A pasteurized milk’ without touch vehicles in order to protect them against ing the lip during the filling. The up dessication. The foreign materials al per 14 inch zone on one bottle was then tered the smooth glass surface and painted with a twenty-four hour old changed the pouring lip; hence, they broth culture as indicated above, the sec-
TABLE 1 The average angles at which approximately 200 cc. of fresh fluid pasteurized milk are poured from a quart bottle. The pouring machine shown in Figures 1 and 2 was used. Volume of milk Angle of bottle in degrees Γη bottle In glass Approximate Average amount From To 950 cc 204.5 cc. 0 78.07 750 cc. 204.3 cc. 78.07 84.3 550 cc. 207.0 cc. 84.3 89.7 350 cc. 208.5 cc. 89.7 96.9 8 Lip Contamination of Mili^ Bottles
ond zone of another bottle was similarly Severa} examples of bottle finishes and painted, and so on through the several the pouring lips as determined by our zones of the six bottles respectively. Thus, method are illustrated in the accompany there were six bottles, each with only one ing drawings. In order to convey to the zone painted with our bacterial indicator. reader thp style of bottle corresponding to In other words, bottle No. 1 had only our type number, a drawing has been the upper *4
LEGEND The behavior of milk poured with use of the Standard Pouring Machine indicated by the number of times the milk contacted the respective zone during the pouring is recorded for each type of bottle tested. The zones indicated on the drawings and the percent figures are based upon one hundred pouring tests. Each type of bottle is indicated by the respective numeral inside the bottle neck. Downloaded from http://meridian.allenpress.com/jfp/article-pdf/1/6/5/2392644/0022-2747_1_6_5.pdf by guest on 28 September 2021 a
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25 Lip Contamination of Milk Bottles Downloaded from http://meridian.allenpress.com/jfp/article-pdf/1/6/5/2392644/0022-2747_1_6_5.pdf by guest on 28 September 2021 Journal of Milk Technology 13
Bottle type No. 20 is similar in design tests, involving the testing of four hun co type No. 14. dred and twenty-six (426) bottles. The Bottles of types No. 22 and No. 23 results are indicated in the diagram. have One protruding angle each located Another glass bottle manufacturer has near the top of the bottle. The diagrams molded this bottle from the blue print showing the results of our experiments sent him. The pouring experiments gave indicate that this principle is not as ef identical results as was obtained with the
fective in reducing the adhesive forces first design made at my suggestion. Downloaded from http://meridian.allenpress.com/jfp/article-pdf/1/6/5/2392644/0022-2747_1_6_5.pdf by guest on 28 September 2021 of the milk poured as recessed angles. Bottle type 21 A (54 mm. diameter) Bottle type No. 21 (55 mm.) is the does pour as well as the 55 mm. (No. best design we have been able to de 21) with the same design. The zone velop so far in our work. The top sur below the lowest recessed angle showed face of the bottle is flat, the first re contact with the milk one time in ten cessed angle is 1/32 inch. This angle pours. is 3/16 inch below the top of the bottle. Bottle type No. 31 (54 mm. diameter) The second recessed angle is 1/16 inch, differs from the 21 A type in that the and placed 1/16 inch below the first first angle recesses 0.04 inch instead of angle. The third recessed angle is 3/32 0.02 inch. The second recessed angles inch placed 3/16 inch below the second are the same on both bottles. The lower angle. Considerable experimentation was angle on the No. 31 is very shallow. necessary to arrange these angles to the It will be difficult to close this type No. greatest advantage. The first recessed 31 with a seal, because of the absence of angle, reinforced by the second deeper a shoulder of glass of sufficient mass to recessed angle, reduces the pouring lip encase properly. This bottle is the best to % inch below the top of the bottle. we have so far tested. Sixty-five pours The lower angle prevents drip of the have been made using the standard pour drop Or two of milk passing the second ing apparatus, and the zone below the angle when the bottle is returned from last angle was not contacted by milk in the 78° angle to the upright position. any instance. The zone between the mid The cap should completely cover all three dle and last recess angles was contacted angles, extending down below the last by the milk in one pour in five. In other angle or 7/16 inch from the top of the words, the first and second angles were bottle. effective in eighty percent of our experi Bottle types No. 24 and No. 25 repre ments ; the next zone was in contact sent our efforts in making slight altera with the milk in twenty percent of our tions in the dressing of the type No. 21. tests. The zone below this third re The main purpose was to make the hori cessed angle was not in contact with the zontal flat top surface less sharp on the milk during or after pourings. margins, and to elevate the outer margin The detail drawings of these two fin so as to avoid possible chipping of the ishes (No. 21 A and No. 31) are shown inner margin adjacent to the seat cap. in Figures 3 and 4. The principle of The results given in the diagrams show breaking the adhesive surface of the glass that these finishes were not so satisfactory by recessed angles is well illustrated in as that of No. 21. The flat top (zone A) these two drawings. played a greater role in the behavior of The overall top diameter of the type the milk poured from the bottle than had No. 31 bottle should be reduced to 51 been suspected or considered. mm. or less. The distance of the last We have worked with type No. 21 for recessed angle from the top of the bottle six weeks in our laboratory. We ordi should also be reduced. Experienced narily do twenty complete pouring experi glass manufacturers state that 54 mm. is ments with each bottle to be tested. Type the narrowest overall size they can make No. 21 has been used for . one hundred at this time. It is believed that such a and forty-two (142) complete pouring bottle will not have the . proper strength 14 Lip Contamination of Milk Bottles if the dressing is reduced to less than Experiments with a new type of finish 7/16 inch from the top in the presence involving recessed angles to interrupt the of a seat cap depression on the bottle. adhesive force of the glass surface have The presence or absence of the cap seat been described. The pouring lip has does not influence the pouring lip of the been reduced to 7/16 of an inch from bottle. It may be possible to reduce the the fop of the bottle so that there is a area occupied by the three anular rings minimum of milk drip during the pour or recessed angles if the cap seat is elim ing. Downloaded from http://meridian.allenpress.com/jfp/article-pdf/1/6/5/2392644/0022-2747_1_6_5.pdf by guest on 28 September 2021 inated. If would be possible to reduce REFERENCES the size of the cap if the diameter were reduced and the external recessed angles Dearstyne, Roy S. and Ewing, C. LeRoy: Num ber of Bacteria on the Lips of Milk Bottles placed closer together. and Their Significance. Am. Journal Pub The design described above can, of lic Health 1920, 10:533-535. course, be put on bottles of larger di Isaacs, M. L. and Zeiben, I: A Comparative ameter. The 5 6 mm. diameter and larger Study of Milk in Bottle with Single and sizes should be easier to make, because Double Caps. Am Journal Hygiene 16: there is more glass to work with in mold 806-822, 1932. ing the dressing. Isaacs, M. L. and Zeiben, I.: Am. Journal The pint and half pint size bottles Hygiene 16:806. should have the same dimensions. The Jackley, J. G.: The Danger of Improperly outside diameter of the neck of a quart Capped Milk Bottles. Journal Dairy Science bottle below the dressing is 1.812 inches. 1922, 5:406. The pints and half pints have an overall neck diameter of 1.750 inches. In order Rice, J. L. Van Saun, Anna I, and Haywood, to utilize the mechanical capping equip Katherine E. Advocating Bacterial Counts on Milk Bottle caps with a Comparison of ment, it is' suggested that the area below the Effect of Different Methods of Capping the last recessed angle on the small size on Such Bacterial Counts. The Nation’s bottles be held at 1.812 inches outside Health, 1924, 6:325-327. dimension for at least y4 inch, and then recessed to 1.750 inch diameter. This Rice, J. L. Van Saun, Anna I., and Haywood, Katherine E. Bacterial Counts on Milk would permit the same mechanical equip Bottle Caps with a Comparison of the Effect ment to be used on all sizes of glass bot of Different Methods of Capping on Such tles. Bacterial Counts. Abs. Bact. 8 (1): 15-20, SUMMARY 1924. (iflec. Expt. Sta. Rec., 1924, 51:778). A standard pouring machine for milk Sansby, J. Martin and Halvorson, H. O. Con bottles, and a standard technique for de tamination of Pasteurized Milk: Including termining the behavior of milk poured Bacterial Study of the Milk After it is from glass bottles have been described. Poured from Bottles Contaminated with B. colt. Presented in part at a meeting of the The degrees of bacterial contamination Milk Sanitary Advisory Board, United obtained from bottles of different fin States Public Health Service, Washington, ishes have been measured, X D. C., May, 1936.