Use of soy proteins in baked foods

Technology for the utilization of soy products in bakery foods is well established and reasonably simple. We can expect the functional properties and flavor of soy products to be continually improved through major research efforts in the soy industry. Large scale protein fortification programs will be forthcoming as the world population continues to grow, and economics dictate more and more efficient sources of nutrients. Before this will be realized, however, careful evaluations of the nutritional requirements and the technical, economic and political situations in a country will have to be made and the constraints removed before widespread use of fortified bakery foods in the commercial sector can be realized. In developed as well as developing countries, the near term constraints for usage of soy proteins in bakery products are represented by food regulations or laws which must be changed before the full nutritional and functional assets of soy proteins can be realized to the benefit of the baking industry.     

Some aspects of research in the application of soy proteins in foods

Some of the work on soy products being conducted at Unilever Laboratories is described. Two off-flavor precursors and several meat flavors have been identified. By studying protein solubility relationships, a new method of concentrating soy proteins has been developed.     

Soy proteins for foods centering around soy sauce and tofu

In the Orient, soy proteins have been used for human consumption for centuries, during which various kinds of unique soy protein foods have been established. Some of these products, such as tofu, have a bland flavor, but there are also those products having a distinctive flavor and an aroma like fermented soy sauce. Both types are acceptable for worldwide populations. In earlier times, the consumption of these soy protein foods in the U.S. was mostly confined to Orientals. Recently, however, the koikuchi type of soy sauce has been consumed widely by non-Orientals through nationwide supermarkets. Annual production in the U.S. has reached more than 16,500 kl. Tofu has also become popular in the U.S. because of its bland flavor which enables it to be used in many dishes. Fermented soy sauce is completely different in the constituents of aroma and flavor from chemical soy sauce. Koikuchi shoyu is a typical Japanese type of fermented soy sauce characterized by a strong, appetizing aroma. The fermentation process consists of koji fermentation byAspergillus species and the subsequent brine fermentation, which contains lactic acid and alcoholic fermentations. Miso is a paste product produced through a similar fermentation. Tofu is a soy milk curd product made through a nonfermented process from soy milk.     

Future of soy protein foods in the marketplace

The food and commodity markets of 1973 signal a fundamental change in values of foods and agricultural products in relation to other goods and services. By 1985 non-traditional protein sources will be depended upon to supply a greater share of world demand for all proteins. By that time use of soy proteins for feeds and specialty foods can be expected to take 2 1/2–3% of an estimated world production of 81 million metric tons/year.     

Nutritional effectiveness of soy cereal foods in undernourished infants

These studies show that a variety of cereal-soy foods can be the major or only source of protein in the diet of growing infants and children. These included various combinations of cornmeal and soy flour, with and without added dry skim milk or methionine; a wheat flour-wheat concentrate mixture or whole wheat flour with soy flour; oat and soy flours; and a corn-wheat-soy flour macaroni. Apparent absorption of nitrogen from each of these mixtures was similar, averaging 76.3±0.6 (SEM) % of intake, but was inferior to that from casein in the same children, which averaged 86.8±0.4% of intake. Apparent retentions of nitrogen averaged 26.6±0.8 and 33.8±1.0% of intake respectively, with all but one of the soy-cereal combinations being similar. This one had a mean retention equal to that from casein, possibly as the result of “instantizing” of the cornmeal which probably resulted in increased availability of dietary energy. For all the mixtures, nitrogen retention was influenced by the efficiency of nitrogen absorption, suggesting that processing methods can improve the nutritional quality of these foods.     

Functional properties of soy proteins

Soy protein ingredients must possess appropriate functional properties for food applications and consumer acceptability. these are the intrinsic physicochemical characteristics which affect the behavior of protein in food systems during processing, manufacturing, storage and preparation, e.g., sorption, solubility, gelation, surfactancy, ligand-binding, and film formation. These properties reflect the composition and conformation of the proteins, their interactions with other food components, and they are affected by processing treatments and the environment. Because functional properties are influenced by the composition, structure and conformation of ingredient proteins, systematic elucidation of the physical properties of component protein is expedient for understanding the mechanism of particular functional traints. The composition and properties of the major components of soy proteins are summarized, and the functional properties of soy proteins of importance in current applications (e.g., hydration, gelation, emulsifying, foaming and flavorbinding characteristics) are briefly reviewed.     

Nutritional aspects in textured soy proteins

Textured soy protein products have found extensive use in pet foods and many human foods. They extend and complement meats in formulated foods. Numerous feeding tests with people and experimental animals show that biological values are high and protein efficiency ratios compare favorably with pure meat products. By careful processing of the textured soy products, high quality, safe, low cost protein food can be prepared. Textured soy proteins are an excellent example of man’s creative ability to engineer a supplementary food that is nutritious, palatable, and economical.     

Soybean proteins in prudent-diet foods

A review is presented on soybean proteins and their health, nutritional, convenience, stability, and economic attributes that justify usage in prudent-diet foods. The concept of these foods is discussed with consideration the contributions of soybean proteins to caloric energy, ratios of polyunsaturated to saturated fatty acid, ratios of polyunsaturated to saturated fatty acids, cholesterol, sodium ion, and levels of sugars. Soybean proteins provide technologists with a cheap, functional protein source for developing meat analogs. Inherent soybean flavors are considered the major unstabilizing problem in prudendiet foods. The energy requirement for producing one pound of meat analog is estimated at 12,300 BTU; soy flour used in it requires only 330 BTU, while cooked meat requires approximately 52,250 BTU per pound.     

Functional properties of proteins in foods

The measurement of functionality of protein food ingredients has developed somewhat haphazardly, probably due to the wide range of proteins used as ingredients and the diversity of foods. Studies of the physiochemical properties of proteins should enable prediction of a proteins response to process environments and prove more fruitful than many of the empirical measurements of functionality. The effects of pH, salt type and concentration on the phase behaviour of the oilseed globulin and arachin, demonstrates the complexity of protein solubility and the inadequacies of simple tests that have arisen. Studies of the effects of salts and conditioning on meat fibres, coupled with measurement of the location of water in pellets from water holding tests enable the latter to be applied with increased confidence. Comparison of the endothermic transitions observed on heating with the development of storage and loss moduli allow the contributions of domains of skeletal muscle myosin to gel structure to be investigated.     

The marketing of isolated soy proteins

The soy protein industry is an established industry today. Current isolated soy protein technology and know-how are practical and being used today. Isolated soy proteins are comparable in protein quality to traditional proteins. Cost effectiveness of isolated soy proteins will offer an economic advantage to processor and consumer. These products are available and strategically located to support commercial utilization anywhere in the world.     

Government role and participation in development and marketing of soy protein foods

Japan has a history of utilizing soybeans as human foods. Currently, a great quantity of defatted soybeans is used as animal feed in Japan, and governmental and commercial enterprises are anxious to turn the defatted soybeans directly into foods for humans. Therefore, they are putting great efforts into soybean research and development. Since the demands for better foods are rising and their resources are not abundant, I feel that soybean protein will play an important role by exerting its unique properties, not only to supplement other foods, but also to grow into new types of foods when their unknown properties are disclosed.     

International programs utilizing soy foods: The world food program

The World Food Program was set up 10 years ago by the United Nations and Food and Agriculture Organization as a multilateral agency to provide food aid where needed. Soy products in the form of corn-soy milk and wheat-soy blend are playing increasing roles in this program described in this paper.