food manufacturing

(food engineering) The commercial production and packaging of foods that are fabricated by processing, by combining various ingredients, or both.

A total sequence of food operations, including the growth and selection of raw materials, harvesting, processing, preservation, and distribution. In general, the aim of all food manufacturing operations is to extend the availability of seasonal crops to year-round use.

The products of food manufacturing differ from traditional foods of plant or animal origin which have undergone minimal treatment. For example, the quality of apples sold in the winter can be maintained, through the use of controlled-atmosphere storage, which retards the ripening process by controlling the levels of oxygen, nitrogen, and carbon dioxide in the atmosphere of the storage facility. Atmosphere control is also used to hasten ripening so that fruits may be harvested in the unripe stage for ease of handling and then ripened rapidly in storage. In other cases the package itself allows the diffusion of only certain atmospheric gases and thus maintains quality. There are certain foods that cannot be maintained in a state close to the raw product. Tomatoes, for example, are not amenable to freezing or long periods of storage. Therefore, such products as heat-processed sauces, pastes, and stewed tomatoes have been developed. Other food products are even further removed from the raw product: oil is produced from seed; and plant proteins are used as extenders or substitutes for meat, as additives for nutritious beverages, and as bases for many formulated foods.

There are many other forms of food preservation representing both ancient and modern technologies. The ancient operation of sun-drying was first employed when it was realized that dried fruits remained wholesome and edible for long periods of time. Today, with the additional knowledge that drying, evaporation, and concentration all reduce the water activity or increase the osmotic pressure of a food to the point where bacteria will not grow, this technology is used for sophisticated products such as powdered milk and freeze-dried mushrooms. Food additives, such as salt, sugar, and other solutes, which reduce the water activity or increase the osmotic pressure, and acids, which inhibit bacterial growth, also achieve the preservation effect. Many food additives are natural in origin, and their preservative effect was noted in nature prior to their use as food additives. Freezing, heat sterilization (canning), pasteurization, fermentation, baking, and meat curing are other well-known forms of preservation. Irradiation processes for food have also been developed, and low-level irradiation has been approved in the United States by the Food and Drug Administration (FDA).

Food manufacturing is not solely involved with the preservation of food but is also concerned with the production of high-quality, appealing, wholesome food. To fulfill these goals, five broad categories of food additives are often used: flavors, coloring agents, preservatives, texturizing agents, and miscellaneous. The last category includes a variety of substances that may retain moisture, control acidity, act as leavening agents, or provide nutrients such as vitamins and minerals.

The final operation in the manufacturing process is that of packaging, which is governed by the physicochemical attributes of the food, the preservation process involved, the gaseous permeability desired, the conditions under which the product is to be stored, the desirability of viewing the product through a clear film or glass, and the expense.

Historically, metal and glass have been used to package heat-processed foods; more flexible films are used for foods which undergo less vigorous treatment. Adoption of the regulation allowing the use of hydrogen peroxide as a package sterilant has permitted the use of nonrigid flexible packages for heat-sterilized foods (aseptic packaging). This type of packaging is very cost-effective. See also Food engineering; Food preservation.