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Home , Aspic, Food processing

Modern Processing

MILDRED M. BOGGS AND CLYDE L. RASMUSSEN

A FEW of the 5 thousand-odd food or warmth. Both processes items sold in a modern super- destroy some organisms but not all. ^ market are fresh, but most of The organisms grow again if water or them are processed—canned, waxed, warmth is restored. dried, frozen, bottled, pickled, pack- Some common ways to slow down aged, wrapped, baked, changed in one chemical changes are to keep way or another. cool, protect them from light, add Stabilization of foods, which keeps chemicals that interfere with reactions, them from spoiling, is a main purpose and minimize contact of the food with of processing. air—by driving the air off with heat, Micro-organisms are the first thing removing it with vacuum, or replacing we think of in connection with deteri- the air of the package with an inert oration of food. Yeasts and molds work gas, such as nitrogen, which does not primarily on acid fruits and cause combine with foods. them to become soured, yeasty, or To cut down the loss of and moldy. Bacteria, the main trouble- minerals, a processor has to keep in makers in most other foods, cause mind that all B vitamins, G, changes all the way from lower quality and some of the minerals dissolve in to putrefaction. water and may be thrown away in Other chemical changes go on all the water. Vitamins A and D dissolve in the time—before, during, and after —for example, in the oil on canned processing and when there is no . Contact with air is damaging processing. , present in every to vitamins A, C, and D. Vitamin Bj living cell, speed up some of the is destroyed by heat in nonacid foods, chemical reactions. even in the absence of air. Light is bad When food is canned, heat destroys for vitamin Bg and perhaps also for A the micro-organisms that cause food and G. All these losses occur faster in to spoil. Hermetic sealing of the cans warm foods than in cold foods. prevents later contamination. The first limitation on the quality of Preservation by dehydrating and a processed food is the raw material freezing deprives the organisms of from which it was made. some condition they need for growth— If a turkey to be frozen has eaten 418 MODERN 419 food that produces the kind of fat that they are processed promptly or kept becomes rancid rapidly, or if the peas cool. * are starchy, the fruit is green, the Peas present a special problem be- variety of strawberries is low in cause some are vined (threshed from and color, the final product will be no vines and pods) at stations some dis- better. tance from the plant. An objectionable Just as not all apples are good for flavor develops quickly in bruised, eating and not all potatoes are good warm peas. The trend has been to vine for baking, not all types of raw mate- at the plant or to water-cool the peas rial are good for processing. Fresh- at the vining stations. market potatoes are produced in The first procedures in the process- nearly all States, but a few varieties ing plant are cleaning, sorting, grad- grown only in special areas are best ing, and preparing the foods as for for drying and freezing. table use—eviscerating the poultry, Different processes for the same food peeling the fruit, straining the , may have different requirements. and so on. Mealy potatoes with a low water The foods must be clean. An inspec- content are best for dried mashed tor can easily see whether a plant is potatoes. The waxy type is best for clean. Standards of cleanliness usually . These two types can be sep- are high. arated with , because the Sorting and grading have a good mealy potatoes sink in it and the others deal to do with the uniformity of packs. float. The extent to which a processor can Economic considerations sometimes afford to separate material into sublots dictate the use of varieties other than adapted to different uses depends those known to be best. Less desirable largely on the diversity of his line of varieties may be included in the total products. Some persons believe that pack in a year in order to extend the separations based on appearance have processing season beyond the short been carried too far and those on flavor time the best variety is available. not far enough. Having decided what raw material Many foods are transported in the to buy, the processor must next make plant in a trough—a flume—of water. sure it arrives at the plant in good Some of the flavoring constituents and condition—as quickly and as cool as , the B vitamins, and min- possible. erals are lost thereby. Some processors Fish and shellfish used to be subject have replaced flumes with conveyor to long delays, but the situation has belts. improved. Much fish is packed heavily After they are prepared for table use, with crushed ice immediately after it most foods receive some kind of treat- is caught. Large quantities are frozen ment, such as blanching, pasteurizing, on ships and are thawed and eviscer- concentrating, or sulfiting. (Each of ated in plants on shore. Some is com- these terms we explain later.) pletely processed—canned or frozen— Many liquid products—milk, cream, aboard ship. These procedures help eggs, fruit juices—are pasteurized. preserve flavor and quality. is mild heating, which Rapid cooling and refrigeration of destroys all or most micro-organisms, milk, eggs, , and poultry are nec- depending on the product. It also in- essary whether they are used in fresh activates enzymes and so helps in re- form or in processing. tention of flavor and color of the foods. Asparagus, sweet corn, peas, and Pasteurization of orange juice that is lima beans are the most perishable of to be concentrated and frozen reduces the processed . They rapidly the amount of separation into pulp and lose flavor, sweetness, general excel- clear layers during storage but tends lence, and vitamins B2 and C unless to take away the fresh flavor. 420 YEARBOOK OF 1959 Batch pasteurization, which involves is lost. Sulfite aids in the retention of heating Hquids at about 165° F. for 15 vitamin C, but it destroys vitamin Bj. or 30 minutes, is giving way to con- Too much sulfite gives a flavor that tinuous high-temperature, short-time most persons consider objectionable. procedures, in which the fluid is rapid- Because we want berries, peaches, ly heated and then cooled as it flows apricots, and cherries for dessert to through a series of coiled tubes. It may as uncooked as possible, they arc take only a fraction of a second and not blanched, but are covered with gives better flavor and color. sirup, which shuts out air and Most vegetables and some fruits are gives them some protection from blanched. Blanching consists of cook- oxidation. ing pieces of food for a short time in Vitamin C sometimes is added to the water or steam. Small pieces, such as sirup for apricots, peaches, and cher- peas, are cooked for about a minute at ries to increase their stability. Oxygen the boiling temperature or for a slight- combines with the added vitamin ly longer time at lower temperatures. instead of with the fruit constituents. Larger pieces are cooked longer. The The vitamin may be used up during purpose of blanching is to inactivate storage. enzymes and thus enhance the reten- Soups, milk, fruit juice, and other tion of color and flavor during storage. liquids sometimes are partly concen- Blanching procedures are not stand- trated before they are canned and ardized. Some processors have a leach- frozen in order to reduce the amount of ing loss of 5 to 10 percent of each material to be packaged, shipped, and water-soluble vitamin or other con- stored. The water is removed at a re- stituent. Others have losses of 40 to 50 duced temperature by means of a percent—or even higher with the same vacuum. There is little impairment of food. quality or nutritive value in this step. Losses are larger in water blanch- The recovery of fruit essence is a ing than in steam blanching and larger special application of concentrating. with long-low temperature treatment It saves the components of flavor. The than with quick-high temperature flavorful vapors that boil oflf during treatment. Industry has changed large- the early of jelly and other ly to quick-high temperature blanch- fruit products are collected, con- ing for frozen green beans, and the densed, and concentrated. The essence color of the product has been greatly may be added to jelly in the final improved. cooking stage, to fruit beverages and Considerable research has been con- juices, fruit-flavored ice creams, and ducted to develop electronic blanch- other fruit products. ing, which would avoid losses through leaching, but a satisfactory procedure IRRADIATION is a potential process- had not been worked out in 1959. ing method for foods. Although no Some dehydrated and frozen fruits irradiated food was on the market in and vegetables are sulfited instead of 1958—in fact, the law did not permit blanched. A few are both blanched and it—millions of dollars have been spent sulfited. Sulfiting consists of exposing on research on irradiation. the food to sulfur dioxide gas or Just as X-rays can be used to destroy dipping the food in a liquid containing cancer cells in the human body, a similar substance. Either way, the gamma rays or high-speed electrons sulfite protects color and flavor of the can be used to kill micro-organisms food by combining with the enzymes and insects in foods. Irradiation does and thus inhibiting them. The chemi- not make the foods radioactive. cal may disappear gradually during The first patent related to irradiated storage at the temperatures used for foods was taken out in France in 1930 dehydrated foods. The protection then by Otto Wüst, but extensive research MODERN FOOD PROCESSING 421 did not start until 1947. Hundreds of as the propionates in ; antioxi- papers have been published since dants, which delay development of one then by universities. Government kind of fat rancidity; emulsifiers, such agencies, and private industries. as the ones used to prevent separation Small exposures to radiation (less of french dressing; bleaching agents, as than 100 thousand rads) have been for ; thickening agents; and sub- used experimentally to prevent sprout- stances to prevent caking of powders. ing of potatoes, destroy insects in flour They are called additives. and spices, and delay the ripening of Relatively few additives were used in fruit. Such low levels usually have 1938. The Federal Food, Drug, and little or no effect on the flavor or color Cosmetic Act passed that year pro- of foods. Radiation dosages in foods tected the consumer at the time. But are now almost always expressed in technologists learned soon thereafter rads. The rad represents 100 ergs of that additives can help food processing energy per gram of the irradiated in many ways. Hundreds of chemicals material. not used in 1938 and many not then In the range of 100 thousand to i known came into use. People became million rads, a medium level, a sort of concerned about the safety of some of "pasteurization" takes place—that is, the substances. After much controversy nearly all the micro-organisms are and study, the Congress passed in 1958 destroyed, but the product is not made the Federal Food, Drug, and Cosmetic completely sterile. After exposure in Act, as amended. this range, , fish, and certain Let us look at these developments in other foods can be kept longer under more detail. refrigeration, and the of The 1938 law did not provide for ad- fruits and vegetables is extended. vance clearance of safety of food addi- Many products sufí'er a serious loss tives. It left it up to the Food and Drug of quality at i million rads, but a Administration to discover their use in lower level can often be found which foods already on the grocers' shelves will improve keeping quality without and to make tests to prove them *'poi- substantial changes in flavor, color, or sonous or deleterious" to the satisfac- texture. Irradiation at these levels may tion of the court in order to remove be used in conjunction with other them from the market. methods of preservation, such as So many additives came into use canning, freezing, or dehydrating. that it was impossible for the Food and Large exposure to radiation (a few Drug Administration to keep up. million rads) sterilizes foods so that Even those for which testing could be they can be stored like canned foods undertaken could stay on the market when they are suitably packaged. Such while the lengthy tests (usually 2 years levels, however, often cause serious of feeding tests with animals) were be- ofí*-flavor, especially in meat and fat, ing conducted. A congressional com- and marked softening of vegetables. mittee investigated chemicals in foods Research is being continued to try and reported that only 428 of the 704 to achieve stability without damaging chemicals used in foods were definitely foods and to reduce the rather high known to be safe. cost of the method. Many sponsors of new food additives Research results as to the safety of made the necessary tests and checked continued eating of irradiated foods with the Food and Drug Administra- are encouraging, but safety had not tion before using the additives. But been proved in 1959. some did not—and the law did not require it. MANY CHEMICALS are added to foods. The 1958 amendment to the food They include coloring agents; fla- and drug law provides that industry voring materials; mold inhibitors, such must prove the safety of chemicals used 422 YEARBOOK OF AGRICULTURE 1959 Variety in Foods^from Processing

DEHYDRO-CANNED

DEHYDRATED

EVISCERATED WHOLE MODERN FOOD PROCESSING 423 in the processing of foods before the Aseptic canning uses these principles. chemicals can be sold for use in foods. The food is processed under conditions The promoter of the additive has to that provide rapid heat penetration. test it for safety on animals and submit Then it is filled into cans and sealed in the test results to the Food and Drug an aseptic chamber to avoid contam- Administration. If the evidence seems ination during these operations. satisfactory under proper conditions of Products prepared by the new proc- use, the Food and Drug Administra- ess in 1959 included several milk, fruit tion issues a specifying the juice, and creamed-soup goods. Many amount that may be used, the foods in other foods have been successfully pre- which it may be used, and any other pared experimentally—baby foods, necessary conditions of use. corn, peas, diced vegetables, tomato If the safety of the additive is not juice, and several kinds of fruit. Very established, the petition is denied. A likely almost any liquid, puree, or promoter who is not satisfied with the small-piece food can be canned suc- decision can ask for a public hearing cessfully by the new process. Foods and court review. that are packed in chunks, such as meat and fish, will have to wait for de- WE ALL KNOW the advantages and velopments in other processes, such as limitations of canned foods. high frequency electronic heating. They are convenient to use, reason- Another new way to reduce the heat ably stable during storage at room damage in canning involves adding temperature, and as safe as we can ex- substances that increase the killing ef- pect any food to be. No case of illness fect of heat on bacterial spores (the traceable to microbial spoilage of com- form in which bacteria are hardest to mercially canned foods has been kill). The substances make it possible reported since the late 1920's. to destroy the bacteria with less heat The color, flavor, and texture of than the usual canning process re- many canned foods are different (be- quires. cause of the long cooking required to Of the 650 substances tested up to make them safe) from those of home- 1958, 26 speeded up the killing of cooked fresh foods. Some people like spores, but some of them are unsuitable the canned foods and simply think of for use with food because of odor or them as different from the fresh foods. toxicity. Among the most promising Canners worked for a long time to are two antibiotics, subtilin and nisin. develop a safe heat process that would Nisin occurs naturally in some types not overcook foods. Now they have one of . Other efí^ective substances that keeps the good quality of many are propylene oxide (which is now used products. It involves heating the food in dried fruit), diepoxybutane, dode- for only a few seconds—at most, a few cylguanidine, and hydrogen peroxide. minutes—at about 285° F. These times Before any of them can be added to and temperatures are approximate. commercially canned food, it must be Many factors determine the exact demonstrated that they kill the spores conditions for a particular food. that have been put in experimentally The new process is called high-tem- canned food. Some canning tests have perature, short-time, or high-short given favorable results. It must be processing. Its principle is that destruc- proved by feeding tests with animals tion of bacteria increases about tenfold that any substance proposed for com- for each 18 degrees of rise in processing mercial application is not toxic under temperature, while the chemical reac- prolonged use. The tests may take 2 tions responsible for the deterioration years. of the product are only doubled. Thus the food is made safe without being DEHYDRATED FOODS usually are eco- overcooked. nomical. Most of them are relatively 424 YEARBOOK OF AGRICULTURE 1959 easy to prepare. Their small weight we described. With the fluidized-bed and volume make them convenient to dryer, enough hot air is blown into store. They are well adapted to use granular-type food so that it flow^s like whenever transportation is a problem. a liquid and is kept in suspension in Much has been done to improve the air throughout the drying time. This quality of dehydrated food. Among the equipment is used commercially in things that have led to improvement the final drying stage for dried mashed are the use of raw material that is bet- potatoes in the form called granules. ter adapted to the requirements of The new belt-trough continuous dehydration; new^ processing technol- dryer tumbles the food on the belt to ogy; more careful application of known give uniform drying. Another dryer processing procedures; less dependence gets uniform heating by turning the on sulfiting for vegetables; improved food from one conveyor belt to another equipment, especially dryers; lower at intervals. moisture content in the finished prod- In prospect is dehydration under uct; and packaging with inert gas. high vacuum—thus at very low drying The aim in dehydrating is to remove temperature and in the absence of air. most of the water from food—some- The drying step can then be done with times 99 percent of it—without dam- little or no loss in the overall quality aging the product. Heat damage causes of the original, unprocessed product. a brown color, scorched flavor, and High-vacuum drying also makes it changes in texture. The first portion of possible to remove practically all of water is removed rapidly, with little the water from foods so that, suitably impairment of quality. Most of the packaged, they store well. damage occurs when the food is almost The high-vacuum process works well dry and water is removed slowly. for the dehydration of fruit juices, Better equipment for spray drying, which are difficult to handle by con- which gives less heat damage during ventional drying procedures because drying, has improved the quality of their high sugar content causes caking dried eggs. A treatment applied to the and sticking. Besides, some fruit juices, egg mix before drying also has helped. especially citrus juice, develop off- An important cause of deterioration of quickly in the presence of air. dried eggs in storage is that the natural Considerable quantities of orange sugar and a constituent of the and grapefruit juice powders produced egg combine to make a substance that by the method were sold in 1958. It is objectionable. The new treatment was expected that blended orange- adds substances that change the sugar grapefruit juice powder and tomato so it cannot combine with the protein. juice powder would be available before Better spray dryers also have im- long. The latter can be reconstituted proved the drying of milk. The quick to single-strength juice or (with less rehydrating quality of the new skim water) to a puree or . The tomato milk powder, how^ever, is due to a sec- powder can be used in dry mixes for ond drying step, which gives the par- tomato , spaghetti sauce, and ticles a fluffy, porous, spongelike struc- similar products. ture. It took 30 years of research to Vacuum can be used with both shelf achieve the powdered—instant—skim and continuous-belt drying of bever- milk that came on the market in 1954. ages, eggs, and fruit and vegetables in Many piece foods are dried on trays piece or juice form. The process is in a forced-draft tunnel, where air cir- rather expensive, however, and was culates past them. Often part of the not widely used commercially in 1959. material is damaged by heat before the Freeze drying, another low-temper- rest is dry enough to store. ature drying method, has produced Several new dryers provide more excellent products, especially meats, uniform and better results than the one which are hard to dry satisfactorily. MODERN FOOD PROCESSING 425 In-package desiccation sometimes ard in a given formula. Thus bakery is used to remove the last small amount products—those the homemaker buys of water from dehydrated foods. A and those she makes—arc likely to be small envelope containing a chemical better and more uniform. (activated lime) is put into the final Cereal foods are enriched to com- package. It absorbs water from the pensate for the nutrients lost in proc- food during storage. The procedure essing to make them stable. A finely avoids the damage to quality that powdered mixture of vitamin Bi, occurs in the late stage of usual de- niacin, iron, and vitamin B2 is added hydration, but it raises the cost a to flour during milling. Stand- little. ards of enrichment have been estab- Many dehydrated foods—including lished for a number of staple foods. many experimental packs produced The National Academy of Sciences- by the newest techniques—were used National Research Council has en- in the ration for Antarctic explorers dorsed the enrichment of flour, bread, during the International Geophysical cornmeal, and white rice. The other Year. A typical meal, weighing a chemicals used in flour, as well as pound, consisted of two dehydrated those in bread, have been evaluated, beefsteaks, dehydrated onions, mashed and specified amounts of each have potatoes, green beans, crackers, been approved by the Food and Drug canned butter, canned fruit cake, Administration. and dried, instant chocolate milk. The protein quality of breakfast cereals—both the prepared cereals CEREALS we may not think of as and the ones you cook—is improved dried foods, but their stability is due in two ways. Sometimes several cere- largely to their dryness. The cereal als, such as wheat, oats, barley, and are dried partly or completely even flaxseed, are combined to pro- in the field. vide a better balance of . The first thing a consumer wants to Sometimes proteins from other foods— know about a cereal food is whether wheat gluten, soybean protein, or the whole seed or only the endo- casein from milk—arc added. sperm—the inner portions of the A growing proportion of cereals kernel—was used in it. The outer reaches the consumer as ready-to- bran layer of the seed and the oily serve breakfast foods—flaked, shred- germ contain important nutrients, but ded, granular, pufled, and toasted they may be discarded because they cereals. Some have sugar coating. do not keep well or because people do The consumer usually pays more for not like them. the prepared cereals than for equal The miller of white flour reduces the nutrients obtained from cereals she endosperm part of the seed to the cooks herself. particle size of flour, blends difl'erent Cereals and foods made from cereals lots to get the properties he wants for account for more than 20 percent of particular uses, and adds chemicals to our food calories, and they furnish speed up the normal bleaching and nearly all of our vitamin Bi. maturing of the flour. A new procedure in milling involves WE BUY much white flour in the separating batches of flour into smaller form of dry bakery mixes, which one lots, each of which is adapted to a can prepare for the oven in a few particular use. Streams of air at minutes. They are scientifically pre- difí'erent speeds separate the heavy pared and yield uniform quality time particles from the light ones. after time when they are finished at Bakers and manufacturers of dry home. There are mixes for angei- bakery mixes often buy flour that cake, butter and fruit cakes, cookies, meets a specified performance stand- piecrust, rolls, muffins, and others. 426 YEARBOOK OF AGRICULTURE 1959 The mixes are prepared in the plant usually find that poor raw material primarily by mixing automatically was used, or it was handled poorly the weighed dry together prior to freezing, or the by hoppers, feeders, and conveyors. was stored too long at too high a Then oil is incorporated into it by temperature. spraying it on the dry ingredients It is possible to freeze so slowly that or by cutting fat into the mix by flavor, color, and nutritive value are machines. impaired, but that is not a common A big problem has been the de- cause of trouble. velopment of rancidity in the mixes. The texture of frozen food is some- It gives an objectionable flavor and thing else. The texture of several is impairs baking quality. Another prob- changed by the freezing itself. Raw lem concerns the leavening agents. salad vegetables, such as lettuce and Sometimes they react before baking tomatoes, become too limp for use. time and cause the finished product Most fruit is softened. Raw ^gg yolk— to have poor volume. Both diffi- but not ^%g white—jells and does not culties have been lessened by drying regain fluidity after thawing unless salt the flour to a water content of 6 to or sugar or glycerine is added. These 7 percent instead of the usual 13 or additives limit the later use of the 14 percent. A strong taste of baking frozen eggs. powder in the baked product means Packages for frozen foods have un- the processor has been apprehensive dergone many changes. Many frozen about having enough leavening agent foods would retain high quality longer left by baking time. if they were packaged in hermetic Other combinations of several dried containers—in the absence of air— ingredients in one package are the instead of in paperboard or other non- dried soups. Each is dried hermetic materials. Only a few foods separately. The extract may be are so packaged, mainly because dried on a drum dryer, the vegetables hermetic containers cost more. in a belt-trough dryer, and noodles Poultry is especially vulnerable to on trays in a tunnel. Finally the drying out, which causes discolored dried spices and seasonings are mixed skin. To minimize this eff'ect, birds with the other ingredients, and the may be wrapped in moisture-imperme- complete mix is redricd. able materials, such as polyethylene. The finished soup is no better than its ingredients. The manufacturers DEHYDROFREEZING of fruits and are looking always for better ingre- vegetables aims to combine the best dients and a more convenient prod- features of both drying and freezing. uct—soup that rehydrates instantly Dehydrated fruits and vegetables oflfer with boiling water, for instance. the economies of greatly reduced weight and volume, but quality may PRODUCTION of frozen foods in- be impaired in the late stages of dry- creased from 275 million pounds of ing. Freezing has advantages, but edible weight in 1932 to 7,329 million costs of storage and transportation are pounds in 1955. Ice cream, cream, relatively high. eggs, poultry, and wholesale cuts of Dehydrofreezing consists of drying meat are not included in the figures. the fruit or to about 50 per- When they are added, the production cent of its original weight and vol- was about 10 billion pounds in 1955. ume—but not to the stage where Flavor, color, and nutritive value of quality impairment occurs—and then most foods change little or not at all freezing the food to preserve it. during the freezing step itself by pres- The quality of dehydrofrozen fruit ent commercial procedures. If a frozen and vegetables is equal to that of the food is poor in these respects, we frozen products, but they cost less (be- MODERN FOOD PROCESSING 427 cause of smaller weight and bulk) to Many micro-organisms are de- package, freeze, store, and ship. stroyed during processing, but some The foods that have been satisfac- almost always remain in the food. torily dehydrofrozcn include peas, They begin to multiply when the food carrots, potatoes, apricots, cherries, thaws. If the food is held too long after boysenberries, and apples. The home- defrosting, ofí'-odors and ofl'-flavors maker buys dehydrofrozcn foods now develop, consistency and appearance only in remanufactured foods—vege- change, and finally the food spoils tables in soup, for example, and fruits completely. Some frozen foods spoil in bakery pies. faster than similar fresh foods, and so they should be eaten reasonably soon FROZEN PRECOOKED foods have de- after they are defrosted. veloped mostly since the late 1940's. The bacteriologist carries out two Today almost a billion pounds of kinds of tests on frozen foods—tests to 200 kinds of these foods are sold. determine the number of organisms They include almost every food pre- and tests to determine whether the pared in the home—soups, meat, food is likely to contain the kind of poultry, fish dishes, nationality foods, organisms that might make people ill. bakery products, desserts, and com- Frozen foods produced under highly plete dinners. sanitary conditions contain only a A number of frozen precooked foods small number of bacteria. They are can be made in almost the same way less likely than foods with a high bac- as the unfrozen foods. They include terial count to contain food-poisoning most , rolls, cakes, pies, other or disease-producing bacteria. Fur- pastries, and waffles. They have essen- thermore, foods prepared under condi- tially the same quality after relatively tions that give low bacterial count also long storage as the product before are likely to be more nutritious and, freezing. They require wrappings that in general, higher in quality. keep the food surfaces from being Although we want frozen foods of soaked with the moisture that con- low total count of bacteria, we are denses on the package during thawing. more concerned about the possible A good many products are relatively presence of even a few bacteria of the unstable. Sometimes the storage life kind that could cause illness. can be lengthened by adding sauces The possible sources of disease-pro- and gravies, which displace the air of ducing bacteria are the soil on which the package. The absence of air re- foods grow, people who handle foods tards the change in flavor that oxida- in processing plants, and, in the case tion would cause—a common cause of of animals, the foods themselves. warmed-over and other undesirable Most specialists believe that the flavors in precooked dishes. frozen foods we cook in the same way The sauces that contain egg or as fresh foods are as safe as similar the usual starchy thickeners—gravies, fresh foods. Examples of such foods are white sauces, puddings, and fillings for frozen vegetables and frozen raw cream pun's—separate or curdle on meats. Both are cooked—not just freezing. Curdling can be overcome warmed—before they are eaten. commercially by the use of special The situation with frozen precooked thickening agents and stabilizers that foods is quite difl'erent. They present are not readily available to home- several special problems and require makers. extra precautions in the processing plant and at all stages until the food is eaten. As FROZEN foods are not sterile, they Precooked foods ofí"er more chances must be handled as perishables from for contamination before freezing than the time they are processed until they do the simpler frozen foods. Most of are eaten. them contain several ingredients, each 428 TEARBOOK OF AGRICULTURE 1959 of which may be contaminated. Op- baked cake. But when we cannot get erations often are carried out by hand, the farm-fresh foods and do not have such as hand boning of chicken. time to bake the cake we are glad to Some of the preparations take time, have the processed foods. and bacteria may increase during delays—especially when various foods BEFORE CONSIDERING the eñ'ects of for one package are cooked separately. the specific processes on costs of foods, The gravy for a plate dinner might be let us look at total costs of food. ready before the french-fried potatoes, Americans spent about 20 billion for example. dollars for food products in 1941. They Another reason some precooked spent nearly 70 billion dollars in 1958. foods require special precautions is They spent 25 percent of their cash that they are not cooked so long at income on foods in 1958. For the same serving time as the similar home-pre- kinds and quantities of food that con- pared foods. Many of the frozen sumers bought in 1935-1939, they precooked foods are not really cooked would have spent only 16 percent of in the home. They are just warmed. their income in 1958. It is obvious that We need therefore to keep such foods our food does cost more. Many factors frozen until we are ready to cook them contribute to this increase besides the so that any bacteria in them cannot additional costs that might be attrib- multiply. uted to processing. Consumption of There have been few authenticated more expensive food items, higher cases of illness traceable to frozen marketing margins, and more food foods. But new processors and new eaten in restaurants are other factors. products enter the field all the time, The Census of Manufactures gives and great care must be taken to insure some indication of the total bill for the production of wholesome products. processing. The value added by manu- The food industries that produce and facturing in food and kindred products distribute frozen foods, as well as amounted to 3.5 billion dollars in homemakers and regulatory agencies, 1939. The comparable figure in 1954 have responsibilities for the sanitary was 13.5 billion dollars. conditions of foods. Early in 1956 The figure for 1939. adjusted to 1954 representatives of industry and food prices and for increased population, and drug officials started a large becomes 9.5 billion dollars. This, then, project of great interest. The purpose is evidence that our homemakers are is to establish sanitary codes for now^ paying 4 billion dollars a year frozen foods from producing plant more than they did in 1939 for the through warehousing and transporta- convenience of having some of the tion to handling at the retail level. work of food preparation transferred The code, a voluntary one, would be to the factory. used as a guide by the various States This figure, how^evcr, does not and municipal food and drug enforce- represent the net cost for this transfer ment agencies. The first draft of the of functions. Having foods in prepared code for frozen precooked foods was form instead of raw form necessarily expected to be ready in 1959. afí*ects the costs of transportation and When we consider all the processes distribution. In some instances, these a food goes through, we realize how costs are less; in others, they are more, hard it is to produce a high-quality mainly because of such factors as food, even with all our scientific con- weight, bulk, and type of storage trols. Quality can be lost at almost required. While the total food process- every step in processing. ing bill has increased on a comparable Most processed foods therefore are basis, processing has lowered costs in not fully equal to strictly farm-fresh many instances. foods or freshly caught fish or home- The first factor that affects proc- MODERN FOOD PROCESSLYG 429 Ejfect of Processing on Cost of Food

COST COST DECREASE INCREASE

Lower purchase price for raw material Decreased waste Upgrading Complete utilization of all grades Processing labor, equipment, and supplies and portions Additives Reduced bulk and weight Quality maintenance Efficiency Packaging Portion control Refrigeration Storage stability Reduced preparation time and cost by user essing costs is the cost of the raw consumer. The shipment of raw mate- material. rial in fresh form and the subsequent Factory purchases of raw material distribution often result in considerable often are made under contracts with wastage and spoilage. Perhaps this loss farmers. Prices so agreed on usually is most obvious in retail stores, where are lower than prices farmers get from often much raw produce is discarded. fresh-market sales, because farmers One source estimates this loss to total may prefer the security of a fixed price 125 million dollars a year for fresh contract over the insecurity of possibly eggs alone. higher but greatly variable prices Elimination of waste parts of the received from the fresh market. Thus, material in processing ofí'ers sub- asparagus for processing in 1957 aver- stantial savings in the costs of packag- aged 168 dollars a ton in California; ing, storing, and transporting food fresh-market asparagus averaged 272 products from farm to market. The dollars. pod, representing more than half the Another factor that helps reduce weight of green peas and lima beans, costs associated with processing is that is eliminated in processed products. factories can use grades of raw Cut sweet corn is only one-third the material that would not be suitable weight of the corn in the husk. Thirty for fresh-market sales. The factories percent of the weight of the wheat can use poorly colored apples, mis- kernel is removed in the production shapen potatoes, jumbo sweetpotatoes, of flour. Canned orange juice repre- small oranges, and eggs having dis- sents about 60 percent of the weight colored shells, all of which are avail- of fresh oranges. able at much lower prices. These A part of these savings in weight is imperfections are meaningless in some offset if , sirup, or sugar is added processes, because the raw material is as in canning. A No. 2V2 can of peaches peeled and cut into pieces, or made may contain 11 or 12 ounces of sirup into juice, or handled in some such and 18 ounces of peach halves. The way. total weight of the canned product Processing converts perishable raw shipped thus is likely to be greater material to a stable form, of which than the weight of fresh peaches used very little is lost before it reaches the in making the pack. 430 YEARBOOK OF AGRICULTURE 1959 Food Costs in Dollars and Hours Expenditures per day for a family of four

3.1 1.6 HOURS HOURS

i $4.50 ^B $5.80 i $6.70 HOME PREPARED PARTIALLY PREPARED READY-TO-SERVE

Processing makes savings possible by packs of apples and apricots containing complete utilization of a crop or ani- no added liquid at all. Concentrated mal. Most meats are sold in fresh products eliminate even more weight. form, but complete utilization of the A can of frozen orange juice concen- carcass is possible only because parts trate represents the equivalent of four not sold fresh are processed into cans of juice. Dehydrofreezing reduces canned-meat products and byprod- the weight and bulk of fruits and vege- ucts. Peel from citrus-fruit processes is tables by 50 percent before freezing. made into feed products. Processing Condensed canned soups represent a of milk makes possible a wide range of 50-percent reduction in weight and products, each utilizing a fraction of bulk. the original—for example, butter, These savings make possible sizable cheese, skim milk, milk powders, and reductions in the cost of packaging, whey. Apples that are rejected from storing, and shipping. Dehydrofrozen fresh-market packinghouses may be peas packed for restaurants could save made into juice; the peel may be the user more than 2 cents a pound, processed for pectin; and the remain- compared with conventional frozen ing cake made into cattle feed. peas. Frozen orange juice concentrate Processing can also, in effect, in- generally sells at prices that are lower crease costs of raw materials and than those for equivalent amounts of produce a product for a special canned juice. market. By selecting a high-quality A complete list of technological part of the original material, a proces- advances would be impossible to make, sor can upgrade the product consider- but we mention some notable ones. ably. Perfect peach halves, packed in heavy sirup, can be sold at premium DEVELOPMENTS that have made im- prices. Other examples of this up- portant reductions in costs are those grading include artichoke hearts, tiny concerned with materials handling peas (petits pois), and white flour. and with continuous processing. One materials handhng method, RECOGNITION of additional costs called hydroconveying, carries the involved in handling and storing un- product in a stream of water, either in necessary weight prompts research open troughs or flumes or in pipes. into ways of reducing these costs. The canning and freezing industries We now have canned vacuum- widely use hydroconveying for mov- packed cut corn containing only a ing such items as fruit and vegetables. small amount of liquid and canned Vegetables of small uniform size, such MODERN FOOD PROCESSING 431 as green peas, lima beans, and cut flaked form. Pneumatic conveyors corn, often are conveyed in water carry flour, milk powder, sugar, beans, through pipes. Specially designed cocoa, coffee, peanuts, malt, and rice. water pumps are used to elevate the Powerful blowers force air at high mixture to higher levels. speed through a duct into which the Continuous or excessive contact product is fed. The duct may run from with water often lowers the quality of one machine or storage container to the product mainly because soluble another within a building, or it may solid components leach into the water. run many hundreds of feet between Products having exposed surfaces re- buildings. The product is separated sulting from peeling or cutting of the from the air in a collector, which per- material are especially susceptible to mits the flow of air greatly to decrease, leaching losses. Hydroconveying does dropping the product at the bottom have some advantages, however, which while the air slowly rises to an exhaust may offset somewhat its disadvantages. vent. It results in transport of material at a These large-scale and continuous minimum of time and labor cost. It transport methods greatly reduce han- reduces desiccation or drying of the dling costs. Older methods use con- product. It partly cools the product, siderable hand labor. The result is a an advantage in the freezing process. lower cost per unit of finished product. Bulk transport also leads to savings. One man can now move hundreds of The material is hauled in large con- tons of product in a large, well-or- tainers, trucks, and tanks without ganized processing plant. being packaged in small units. A tank Factory preparation of food offers car, an example of a bulk transporter, cost advantages to be gained from the can carry dry or liquid materials. large-scale and scientific processing. Sugar in liquid form, which many Newer types of cookers in canneries are factories use, can be delivered in tank continuous. The batch type was used cars or trucks and transported within previously. Even butter, cheese, and the plant through a pumping system. ice cream can now be made in con- More and more milk is handled right tinuous processes. Continuous diffusers from the farm in bulk in tank cars or give an improved extraction of sugar trucks. from beets and drastically reduce labor Bulk transport also is used for , costs. Continuous ovens, automatic peanuts, and soybeans. Many fruits bread depanners, and band slicers that and vegetables for processing are can slice 50 to 60 loaves a minute have carried in bulk. Large containers, become common. called tote boxes, each carrying as A piece of equipment usually is much as a ton or more, are used for classified as continuous if the items it hauling raw material to the plant. handles are fed to it and discharged Within processing plants, large bins without interrupting its operation, are used to carry dry ingredients, such with little if any requirement for labor. as flour. Lift trucks are finding an An oven in the home is a good example ever-increasing application. These effi- of a batch machine. It cooks one loaf, cient machines can lift a tote box or a cake, pie, or load at a time. A con- pallet load of cases or boxes weighing tinuous oven may consist of a very several tons to heights above 20 feet long chamber through which a belt and can carry the loads quickly moves continuously. The burners throughout the plants and loading within the chamber are so located and yards. regulated that items of bakery goods Pneumatic conveying, or carrying can be fed continuously into one end materials in a stream of air, is finding and emerge completely cooked. increasing application in handling Citrus fruits are squeezed for juice products in powdered, ground, or automatically. Peaches, pears, and 432 TEARBOOK OF AGRICULTURE 1959 apricots are automatically filled into ing enough material for serving four cans in contrast to costly hand filling persons. Individual servings of jam previously used. Exhaust boxes have and chocolate-beverage powder are given way to vacuum closing, which other examples. Portion packaging in- saves processing time. High-vacuum, creases container costs, but it may low-temperature, continuous evapo- avoid waste in the kitchen. rators are used extensively in produc- Frozen, canned, and dehydrated ing citrus juice concentrates, tomato foods have advantages and disadvan- pastes, and other concentrates. tages as to costs. New continuous types of dehydrators As a group, dehydrated foods gen- find increasing application. The belt- erally offer the greatest cost savings trough dryer dries fruit and vegetables to the consumer. They are greatly re- uniformly with a minimum of labor. duced in bulk and weight. They do not The investment cost per unit of drying require costly storage temperatures. capacity is low. Packaging requirements generally are AH of these advances have brought not critical. Dehydrated foods are not about important reductions in proc- always the least costly, however. De- essing costs, despite large investments hydrated foods become more expen- generally required to set up factories. sive if vacuum drying is necessary and Low unit costs are made possible by if the output is small in relation to size the large volumes of food that are and cost of equipment. Two examples: efficiently put through the plants. Ordinary dried apples are usually the Costs of packages for processed foods lowest in cost of all processed apples. vary greatly. Sometimes the package A new product, vacuum-dried orange may cost as much as the food itself. juice powder, however, is likely to be Hermetic containers, such as are neces- quite costly, even more than the equiv- sary for canned products, are relatively alent quantity of frozen or canned expensive. So are containers for liquids juice. Not only must dehydration be or products that become liquid. carried out under a high vacuum, a The container cost is reduced if a relatively costly process, but the prod- product can be held so that it does not uct must be hermetically sealed to pre- need a hermetic seal. Thus the paper- vent a gain in moisture content. board package for frozen peas and the Canned and frozen foods ofí"er ad- cellophane bag for dried fruits are less vantages and disadvantages in costs. costly than the tin can for these canned The higher cost of the tin can is a dis- foods. Some of the new materials, such advantage. The higher cost of freezing as foil and a plastic film laminated to- temperatures for transportation and gether, are nearly hermetic and inter- storage of frozen foods also is a dis- mediate in price between tin cans and advantage. The relative importance simple films. Aerosol, or bomb-type^ of these factors differs with each prod- packages are expensive. uct and situation. We might say that Packaging costs can be reduced by frozen peas should usually be sold reducing the amount of water included at a lower price than the equiva- in or with the food to be packaged. lent canned, but that canned con- Dehydrated mashed potatoes repre- densed soups not requiring refrigera- sent about one-fifth the weight of tion should be cheaper than frozen peeled raw potatoes. Orange concen- soups of the same degree of concen- trate represents one-fourth of the tration, because both are packaged weight of the juice. in tins. Portion control has been receiving One question that naturally arises in much attention. A package of meat any discussion of changes in processing may contain four equal-sized servings. costs is whether the increases in costs A package of dried mashed potatoes and the savings have been passed on to may contain two envelopes, each hoid- the consumer. The answer is obviously MODERN FOOD PROCESSING 433 yes, but it would be difficult to deter- study, trained home economists were mine the exact effect on retail selling the cooks. Some homemakers might prices. Any such changes have been not do so well, but most homemakers masked by other changes, such as have the knack of preparing foods the changes in the cost of farming, in- way their families like them. creased marketing margins, changes in package size and types, and even THE RAPID RISE of convenience and changes in process formulas. For some variety foods leads us to expect more items that can be directly compared of them, if the general economic situa- over a period of 20 years, for example, tion is favorable. Consumers have frozen peas, data can be assembled demonstrated that they place con- that show retail prices have not in- venience high in their choice of foods. creased proportionally as much as the Processors will probably pack an in- general price level. creasing percentage of foods in con- A study conducted by the Depart- centrated or semiconcentrated form in ment of Agriculture in 1953 provides order to offset as much as possible comparison of cost of actual meals mounting costs of labor, supplies, and from home prepared, partially pre- distribution. pared, and ready-to-serve foods. The Many processors and food research- study included an evaluation of quality ers expect expansion of what they call and time to prepare the comparable combination processes—the use of meals from different types of foods. It processing steps that have especially included meals for 2 days for a family good features. Dehydrofreezing is an of four, including two teen-age chil- example. The excellent container for dren. The meals were described as canned foods might be more widely being a little more varied and expen- used for dehydrated and frozen foods. sive than the everyday meals of most Canned and dehydrated foods might families. be stored at reduced temperatures (40^ It took the homemaker 5.5 hours a to 60^ F.), but not at freezing tem- day to make home-prepared foods, in perature. Irradiation might serve as a which bakery bread was about the supplementary step for any of the usual only prepared food. When she used preservation methods. Perhaps more partly prepared foods, which included fresh foods will be pasteurized. We such things as apple pie from canned cannot exclude the possibility of radi- apple and bakery mix, about 3.1 hours cally new processes. were required for preparation. When ready-to-serve meals were used, 1.6 MILDRED M. BOGGS has worked in food hours were involved. The latter in- technology research since igj6 at the State cluded frozen apple and beef pies but College of Washington Experiment Station not a frozen complete dinner. The and {since 1942) in the Western Utilization meals cost 4.50 dollars for the home- Research and Development Division of prepared foods, 5.80 dollars for the Agricultural Research Service^ Albany^ partly prepared foods, and 6.70 dollars Calif. She studied at the University of WiS' for the ready-to-serve foods for the consin, Columbia University, and Cornell family of four for a day. University. The home-prepared meals were CLYDE L. RASMUSSEN is in charge of liked best, but those from partly pre- Industrial Analysis Investigations in the pared products were considered nearly laboratory in Albany, Calif., and makes as acceptable. Meals from ready-to- studies concerning the economic feasibility serve foods were less acceptable. Indi- of processes and market potential of products vidual foods within each group, of under study in the Division. He has worked course, differed in acceptability. The in economic and cost analysis in several quality of home-cooked foods would Government agencies and has had experience certainly depend on the cook. In this in various food-processing plants. 477248"—59- -29