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Food Technology

( Originally Published 1939 )

Scope. The development of the food industry to its present status has been brought about by the application to commercial practice of the findings of chemists, bacteriologists, physicians, engineers and veterinarians. Science furnishes the principles; commerce supplies the financial means and utilitarian interest; and engineering connects the two by translating ideas into practice. All this is the basis of food technology.

The field has been described by Cruess as a combination of chemistry, bacteriology, and biology. Food technologists have been characterized by Cronshaw as enzymes who sort out the data supplied by the laboratory and build up the selected parts into the form best suited to the requirements of the industry which they serve. Lewis states that they should be able to rise to the responsibilities of public health, national economics, and the ethics of food nutrition and advertising, and that they should be well-trained scientists who have acquired the tempo of the commercial world. Food technology embraces the sum total of the knowledge acquired by the plant chemist or the bacteriologist who has found out how to apply scientific information to the practical operation of food manufacture. It is more than this. It involves, in addition, some knowledge of the subjects of engineering, public relations, advertising, purchasing, merchandising, economics, cost accounting, law and patents, plant management, regulatory control, and quality supervision.

The food technologist is the plant official to whom the public-health officials should look for the proper application of the regulatory standards of product and operation, and one who would be expected to understand their objectives and methods. However, decisions regarding labeling are often made by merchandising or advertising men who overrule the recommendations of the food technologist. This is a common source of misbranding. The food technologist is the liaison officer between business management and the professional groups such as the health department, the regulatory officials, the educational interests, and the world of scientific progress.

An extension or special application of food technology is food engineering, somewhat analogous to such specialized engineering as the mining, aeronautic, and communications branches. The food engineer could serve the food industries as profitably as the chemical engineer has the chemical industries. Moss points out 6 that many problems which arise in commercial food operations cannot be handled by the food chemist because of his lack of technical training, or by the food technologist because of his lack of formal engineering training. Food technology is a field for the executive type of trained food chemist with many years of practical experience and with a fair knowledge of the principles of chemical engineering.

Other special applications are in the fields of writing, economics, patents, regulatory control, and business. Through this route of food technology, the food chemist and the bacteriologist outgrow the laboratory and make places for themselves in larger fields of food handling.

Principles of production practice. The food industry is built on practices which originated in the remote past. Each particular industry like dairying, baking, meat packing, fishing, and food preservation grew more or less independently of the others. Their occupations became highly developed commercial arts which were perpetuated by the teaching of the accumulated results of experience to succeeding generations. An analysis of these practices shows that in principle they are similar to those which have been observed for a long time in the chemical industry. As Burton has pointed out, food processing differs but little in its fundamentals from other forms of chemical processing. It constitutes a specialized form of chemical engineering. It deals almost entirely with the production of materials of biological origin, using operations which are fundamental in the chemical industry.

Unit operations. The editors of the journal Food Industries analyzed the practices of 107 different food-manufacturing procedures, and grouped them into a relatively few operations, in fact 15, which are common to the entire food industry (Food Industries, February 1937). These are called unit physical operations, defined later as follows:

A unit physical operation in food engineering is a controllable or intentional change of form or place of a food material or ingredient.

This list can be condensed to 12 unit physical operations illustrated respectively by some of the more common food-handling procedures, as follows:

1. Coating—dipping, enrobing, glazing, icing, panning, sugaring, topping.

2. Controlling—air conditioning, humidity control, inspecting, level control, measuring, pressure control, temperature control, tempering, weighing.

3. Disintegrating—breaking, chipping, chopping, crushing, cutting, grinding, macerating, milling, pulverizing, refining (by conge, roll, or melangeur), shredding, spraying.

4. Drying—air or spray drying, atmosphere drying, heat drying, mechanical drying, vacuum drying.

5. Evaporating—atmospheric pressure or vacuum evaporating.

6. Forming—casting, embossing, extruding, flaking, imprinting, molding, rolling, sawing, shaping, slicing, splitting, stamping or die casting.

7. Heat exchanging—blanching, chilling, cooling, dissolving, exhausting, freezing, hardening, melting, pasteurizing, refrigerating, sterilizing.

8. Materials handling—conveying, factory trucking, gas compressing and handling, liquid handling, liquid pumping, semi-solids pumping, shipping, trucking.

9. Mixing—agitating, beating, blending, diffusing, dispersing, emulsifying, homogenizing, kneading, stirring, whipping, working.

10. Packaging—boxing, capping, cartoning, closing, double seaming, filling labeling, wrapping.

11. Separating or concentrating—centrifuging, clarifying, cleaning, crystallizing, cycloning, draining, evacuating, exhausting, freezing for concentrating, filtering, percolating, pitting, pressing, refining, riffling, screening, sedimenting, sifting, skimming, sorting, tabling, trimming, vacuumizing, washing.

12. Storing—piling, stacking, tanking, warehousing.

It is not likely that such a classification in every particular will receive the unqualified approval of all food technologists and engineers. Some of the groupings are arbitrary; possibly some have been omitted. However, this or a similar classification systematizes our knowledge of many seemingly diverse operations and directs attention to a few principles which are broadly applicable.

Unit chemical processes. The manufacture of foods also involves changes in chemical composition. A unit chemical process may be defined as follows:

A unit chemical process in food engineering is an intentional or controllable change of composition of a food material or ingredient.

It is difficult to group all the processes of the food industry in terms of their chemical reactions. Certain ones like fermentation, hydrolysis, oxidation, and reduction are easily classified. Other processes like cooking, ripening, staling, denaturing, brewing, roasting, and others are not well understood from the standpoint of all the chemistry involved. The main chemical changes are known, but the production of bouquet, "nose," and, other elusive organoleptic qualities involves reactions whose measure is almost entirely sensory or subjective.

Progress in understanding these reactions will probably be slow and empirical until we find a means of measuring objectively these imponderable properties. At the present time, it is impossible to classify these processes in any other terms than descriptions of the operations themselves.

Problems in food technology. As old problems in the food industry are solved one after another, new ones are continually arising. The sudden appearance of a peculiarly heat-resistant strain of microorganisms in milk to be pasteurized or in vegetables to be sterilized may require a drastic examination of the raw supply to locate the trouble for correction or elimination, and to adapt the processing procedure to meet the new conditions for as long as they may last. The production of a new food product, the use of a new source of raw materials, the application of a new type of equipment, seasonal changes in temperature, the adoption of new regulatory standards, the appearance in the market of some new competitive product—these and many more factors indicate some of the problems which the industry must solve within the limits of approved regulatory and sanitary practices. It is customary to endeavor to manufacture new products in the light of the knowledge gained in the treatment of similar products. Sometimes this procedure works out fairly well, but never to complete satisfaction, and usually it needs more or less drastic change, as experience in its handling demonstrates that no two commodities ever have precisely the same properties. When sudden and other unusual difficulties in food processing are encountered, some of the finished food may not be quite up to standard.

The food-control official must know how to recognize and interpret these special conditions. He can ignore the unusual nature of the operating difficulties and drastically enforce the regulatory standards, regardless of whether or not the producer is endeavoring to correct the difficulty. The price that he pays for being that kind of enforcement officer is the loss of the opportunity of collaborating with the plant personnel in learning what caused the unusual condition. The knowledge of the cause indicates the means that may be used to prevent a recurrence of the same difficulty in other plants. By following such a program, the inspector maintains the respect of the plant operating personnel, increases his own knowledge, and constructively serves the public interest.

The last service becomes apparent when the food-control official can take the initiative in designing better types of equipment or devising improvements in food processing. If he is adequately trained and widely experienced, he possesses a wealth of knowledge of operating conditions which often enables him to apply to certain difficulties the remedies found to be effective elsewhere. He is in a unique position to guide the developments in new equipment designs by indicating where present designs are unsatisfactory and what standards of performance are desired. Thorough training in food technology is as important to the food-control officer as the knowledge of chemistry is to the sanitary engineer or bacteriology to the health officer.

Trends in the food industry. The food industry, like all other industries today, is not confined to permanently fixed practices. It is undergoing change and development like other businesses, in legal regulation, in political conditions, in economic periods, in market demands, and in consumer preference. Increasing shipping distances, widening distribution, and increasing demands for quality are trends of the times. New equipment is being designed, merchandising methods are changing, public taste is varying, and regulatory super-vision is increasing. Other commercial trends in the food industry may be listed in part as follows:

Improved appearance of product.

Greater convenience to consumer.

Better packaging.

Greater nutritive value by natural or artificial means.

More protection from dust, microbic infection, and human handling.

Better maintenance of original quality and flavor, and less deterioration during processing and manufacture.

Improvement in methods of preservation. Economies in operations.

Introduction of continuity in operations. More effective quality control.

Greater dependence of production and operations on technology.

Greater dependence of advertising on scientific information.

More aggressive merchandising.

Development of tray agriculture.

Preparation of menus and recipes.

Expansion of variety of products.

Development of new non-competitive products. Utilization of by-products.

Training of personnel to greater efficiency in the particular business. Welfare of employees.

Improved industrial hygiene.

Improvement of public relations.

Research activity in the food industry is increasing. Although one of our largest basic industries, it has been one of the slowest to recognize that its continued progress must be built on a solid foundation of research. It explores the market possibilities for new developments in the expansion of the business. It examines competitors' products in order to appraise its own relative position. It sifts and evaluates the newer discoveries in science, and interprets them in the interest of the business. Research that is industrially supported is engaged almost exclusively in applying available knowledge to commercial operations; it is not contributing much to opening up new fields of knowledge. Fundamental research in the production and composition of food, human nutrition, food chemistry and technology, and food preservation is being actively prosecuted by government, state, and university laboratories. Examples of some present activities in both fields are as follows:

Search for factors which affect flavor.

Preservation of fruits, vegetables, and animal products by freezing, drying, heating, treatment with light, and storage under gas pressure.

High temperature-short time (high-short) heat treatment for pasteurization and pressure sterilization.

Air conditioning by control of temperature, humidity, content of suspended dirt, content of inert gas, and treatment with ultra-violet light.

Development of metallic alloys resistant to corrosion by foods. Cytology of foods.

Enzymology of foods.

Ecology of food microorganisms.

Microbic effects on foods.

Determination of incipient decomposition.

Improved methods to detect adulteration and contamination.

Vitamin protection and determination.

Factors affecting nutritive values.

Nutritionally important constituents of foods.

Nutritive needs of the body.

Relation of nutrition to infection.

Microbiology of foods.

Study of flavors.

Study of staling.

Relation of food to the publie health.

Conservation of nutritional value in the cuisine.

Utilization of by-products.

Chemical methods for the determination of the vitamins.

Chemical methods for the determination of adequate heat treatment.

Research in this field, extending from raw materials to final markets, will probably continue to be active.

Industrial hygiene. Some food manufacturers have been pioneers in supervising the health of their employees. In the early days, this was mostly directed only to manicuring because of its obvious relation to esthetic considerations in the manual handling of foods. This supervision now embraces the medical examination of all employees who work in direct contact with foodstuffs, the wearing of caps or hair-nets to prevent hair or dandruff from falling into the food, the use of clean uniforms to encourage the habit of cleanliness, and the practice of good housekeeping in plant operations. The advent of the various types of liability and compensation insurance, together with increased emphasis on safe plant practices, has led to the improvement of hygienic and other sanitary conditions in many plants. A step beyond this has been taken by some companies whereby well-organized industrial health services are directed by full-time health officers, who not only supervise insurance, injury, and welfare cases, but also instruct the employees in personal hygiene. This sort of protection far out-weighs any number of official regulations concerning employees' con-duct in relation to food infection and contamination. The application of industrial hygiene to food industries makes plants easier to clean and more likely to be kept clean by reason of sanitary construction, better lighting, increased incentive to cleanliness, and more intelligent direction.

Quality control. In industry, quality control reaches farther than official quality control. It covers all provisions that are required by official regulations, such as health of employees, sanitation of plant, wholesomeness of products, and compliance with legal standards, but it also supervises other aspects of quality and public-health values. For example, the flavor of foods is given almost no consideration by regulatory officials, but this is one of the most important commercial considerations. Milk may be pure and yet unpalatable. The texture of a food does not interest control officials, but it is of prime value in business. Ice cream that is coarse or soggy or soft may be legal but unsalable. Bread may comply with the law, but the public may not relish it.

In addition, an aggressive food business must engage in advertising and other activities to attract consumer attention. This often takes the form of instructive leaflets, broadcasts, lectures, demonstrations, and other educational efforts in matters of nutrition and the attractive preparation of food for the table. Such programs usually are closely related to the work of quality-control staffs, and their technical information is sought by the copywriters and the publicity agencies.

Moreover, the quality-control staff of a plant often possesses a detailed knowledge of the performance of processes and the quality of products which cannot be learned by the official inspection force, who necessarily spread their activities over a wide territory and devote only a relatively small amount of attention to any particular one. On the other hand, the official inspectors possess a breadth of experience concerning many different types of operations that cannot be seen by competitors. Collaboration between the two groups checks the tendency of manufacturers to exploit the public and also restrains the regulatory officials from adopting unreasonable standards and from over-emphasizing the non-essentials.


1. W. V. CRuEss, Food Manufacture, 10, 211 (1935).

2. H. B. CRONSHAW, ibid., 288. See also pp. 89, 91, 133, 169, 208, 287, 315, 357.

3. W. L. LEWIS, ibid., 212.

4. Editorial, Food Industries, 3, 462 (1931).

5. Ibid., 8, 79 (1936).

6. W. W. Moss, Chemist, 13, 455 (1936).

7. L. D. BRISTOL, Industrial Health Service, Lea and Febiger, Philadelphia, 1933.


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