Soy processing: From beans to ingredients

Soybean processing does not end with the products oil and meal. To the food ingredient business, this is only the beginning. This presentation is a simplified general scheme to show the processing of soybeans from the whole bean to each of its end protein ingredients and to show where they might fit into the food business. It portrays bean preparation and oil extraction, meal handling, and conversion of the meal into food ingredients. Soy flour, soy concentrates, soy isolates, and modified protein products, such as spun fibers and textured vegetable protein products, are covered. Some values and applications of the ingredients also are discussed. One of 13 papers presented in the symposium, “Soy Protein,” at the AOCS Spring Meeting, Mexico City, April 1974.     

Designing vegetable proteins to fit market needs

The needs and wants of the market are discussed as well as the regulatory practices that frequently inhibit the fulfillment of the market’s requirements. The advantages and short comings of the various types of protein ingredients are described, and appeals are made to the soy protein-producing industry to protect the integrity of traditional products by recommending extension of meat and other products in such a manner as to preserve their traditional character. Improved technical service offered to the food processors can bring added assurance to the consumer of a continuing supply of quality traditional products. The soy protein industry must continue the development of their own products so that broader application is possible. The inherent nutritional and functional values of soy proteins are such as to make a new generation of textured products, and improvement in the functional properties of concentrates and isolates a very realistic goal. Compatibilities of soy proteins with other proteins and ingredients are discussed; suggestions are made that the inherent synergism in many of these combinations is an untapped developmental area that will enable us to design protein ingredients for specific applications and thus benefit the consuming public, as well as the food processing industry.     

Soya products in meat,poultry and seafood

The soya protein industry has produced a wide variety of products with specific functionality properties to meet the targeted needs required by the food industry. It is important to recognize that certain of these soya protein products have and perform specific functions in these foods, such as texture forming, gelation, fat and water binding, and emulsification. They contribute to the nutritional and general overall eating quality. Also important is to recognize the limits of application of soya protein technology based on maintaining the traditional quality of the meat, poultry or seafood products. Today, unlike just a few years ago, soya protein products are able to contribute to, not just extend, high-quality meat, poultry and seafood products. The combination of resource efficiency of soya proteins and new technological advances is constantly expanding the long list of applications worldwide. The function of soy protein products in a variety of processed meat, poultry and seafood products is discussed. Paper presented by C.W. Kolar.     

The U.K. legislative approach to the use of soy proteins in food

The food and drugs acts applicable within the U.K. provide a framework within which the sale of all foods is controlled. In particular the main clauses place responsibility for safety and avoidance of deception firmly on the manufacturer and seller of the food. The significance of compositional regulations, made under powers contained in the acts, is illustrated by the various meat product regulations and their relevance to the use of soy materials. Food labeling regulations also are discussed. The directions in which the laws may have to be revised to accommodate the introduction of new protein rich foods are outlined and the relevance to soy products is discussed.     

Processing and product characteristics for textured soy flours,concentrates and isolates

During the last 25 years, the development of processes to provide textural properties in soy proteins has greatly increased the market potential for soy protein products. Many different processes based on soy flour, concentrates and isolates have been developed. They have ranged from products to be used in extension of meats to meat analogs themselves. The real success of new processes is measured by their success in the commercial marketplace. The most successful products have been based on thermoplastic extrusion of soy flour. More recently, second generation products made by the thermoplastic extrusion of soy protein concentrates have been introduced. These products have less flavor, wider variety of functional characteristics and greatly reduced flatulence characteristics compared to textured soy flour products. This paper describes processes used to texturize soy proteins and characteristics of the various products. Product characteristics, functionally and economics are key factors in deciding which product to use in end-product formulations. The wide variety of textured soy proteins available provides a product for each individual need.     

Comparative functionality of soy proteins used in commercial meat food products

The use of soy isolates, concentrates, and texturized flours in meat food products is discussed. Functional characteristics of soy products in relation to their market application are reviewed. Soy isolates find more limited usage in meat food systems (2%) than the concentrates and textured soy flours (8–12%). In weak meat systems containing large amounts of fat (30–45%), the concentrate emulsifier and isolate are more important than the texturized soy flour. In chopped meat systems with 18–25% fat, the textural properties of soy flour (extruded) are more important than the use of an isolate. However, combinations of concentrate emulsifier and texturized flour are used. The method of cooking, i.e. fresh, deep fat-fried, or char-broiled, will affect the usage of soy combinations. In comminuted cooked cured meat food mixes, soy concentrates, and textured flours currently are being used. Nutritional properties are improved by inclusion of available ingredients high in lysine and methionine. Functional measurements of textural properties have been completed using the Instron with a Lee Kramer cell. Both model emulsion systems and finished product results substantiate the accuracy of textural properties in soy-meat mixes using the Instron.     

Defatted soy flour and grits

Defatted soy flour and grits are the most rudimentary forms of high protein products processed from the soybean, yet they are the soy products used in the largest volume by the food industry. To appreciate fully the contribution of defatted soy flour and grits to any food system, it is essential that a knowledge of the composition, nutritional value, and functionality of these products be well understood. Major emphasis is given to applications for defatted soy flour and grits with cereals.     

Soy protein products and their production

The soybean industry in the U.S. started in the first years of this century and was only 5,000,000 bushels just 50 years ago. This year it is expected to be over 1.5 billion bushels, reflecting a remarkable growth. Beans are processed primarily for soybean oil and for meal to be used in poultry and livestock feeds. Only ca. 3% soy protein is used in human food today. Special processing is required to prepare proteins to meet the various specifications of products for the food industry. Methods used to produce flour and grits, spun fibers, textured proteins, concentrates, and isolates are described.     

Textural contribution of vegetable protein products

Many textural characteristics of food products may be affected by soy protein products. Texture may produce, may limit, may restrict certain of the functional properties of soybean products which have been discussed at this meeting. This paper describes some of the types of textures which soybean products contribute to food products, some of the methodology employed in producing the more common textures, and the rationale for the production of varying textures.     

Soy protein foods in U.S. assistance programs

Soy protein food products occupy an important place in both U.S. overseas and domestic food assistance programs. In the overseas food donation program the products serve as the source of protein for the fortification of conventional processed commodities—wheat flour, corn meal, rolled oats, bulgur, and sorghum grits—and as a major source of protein in several cereal soy products designed for special use as child food supplements. Acceptance of these products has been good and more than 1 billion lb. of soy-fortified foods were distributed in the overseas program during July 1, 1972-June 30, 1973. In domestic food assistance programs, soy protein foods which meet U.S. Department of Agriculture requirements have been introduced into both school lunch and breakfast programs and also are distributed to needy families. Two products, textured soy protein and protein-fortified enriched macaroni, are permitted to meet part of the meat requirement in the Type A school lunch. In the school breakfast program, soy protein is a permitted ingredient in protein-fortified foods such as doughnuts, cake-like baked products, and cereal-fruit products. They were introduced primarily to meet the need for nutritious food items that require no kitchen facilities to prepare and are convenient to serve in schools that lack food service facilities. Specifications for the various food products are presented.     

Technical problems and opportunities in using vegetable proteins in dairy products

The food processing industry is giving increased emphasis to the production and utilization of alternate protein isolate products as functional and nutritional ingredients in an expanding number of formulated food products. Alternate protein sources such as soy and other vegetable proteins offer additional flexibility in formulating foods due to their economics, availability, functionality and nutritional properties. This paper discusses needs for developing soy and vegetable protein isolates with improved flavor, color and functionality for producing simulated dairy foods. It also considers alternative technologies for incorporating soy and vegetable proteins into the formulation so that they may function properly for forming stable solutions, emulsions, foams and gels that resemble those in their natural dairy food counterparts.     

Melt-spun poly(lactic acid) fibers modified with soy fillers: Toward environment-friendly disposable nonwovens

Poly(lactic acid) (PLA) has a significant potential as a biodegradable polymer, but its high cost and slow biodegradability restrict its use in disposable products. This study establishes a novel route to accomplish both objectives by the addition of low-cost soy fillers into PLA, which reduced material cost and increased the degradation rate of resulting soy-PLA fibers. Due to partial thermal degradation of soy fillers at PLA melt temperature, they could be melt-compounded into PLA up to 5 wt%. Fine continuous fibers (D ∼ 25-50 μm) were successfully produced via melt spinning, and further melt-consolidated into prototypical nonwovens. The tensile strength of soy-PLA fibers containing soy reside and soy flour were 56 ± 9 and 44 ± 5 MPa, respectively. Although slightly lower than that of neat PLA fibers (74 ± 2 MPa), the fibers possessed adequate tenacity for use as nonwoven fabrics. Fiber modulus remained unaffected at about 2.5 GPa. The soy-PLA fibers displayed a relatively rough exterior surface and provided a natural-fiber feel. The overall degradation of soy-PLA fibers was accelerated about 2-fold in a basic medium due to the preferential dissolution of soy that led to increased surface area within the PLA matrix indicating their potential for use in biodegradable nonwovens.     

Entwicklung und Bedeutung pflanzlicher Proteine in der menschlichen Ernährung

Development and Importance of Vegetable Protein in Nutrition For several decades it has been a common practise to use concentrated vegetable fat and carbohydrate products in food processing, as well as institutional and house-hold food preparation. This is not true for vegetable protein products. Now, a new list of products are available, which have a wide protein range (50–90% crude protein) and which are ground, textured and spun and which have useful diversified functional properties. These products are finding a growing need and interests in the food industry. For 1975, the total U. S. consumption of soyprotein products reached about 170 000 t with an annual growth rate ranging from 3–25% for the individual types of products. The costs of the common soy protein products range from DM 1.50–5.30/kg crude protein for industrial uses in 1976. Comparing the costs for 100 g crude protein in soy products with other selected food items, which mainly cover the protein requirement, soy products range from 0.18–0.55 DM. This compares to a fraction of the protein costs of other foods. The principle functional properties, resulting from the protein dispersability and enzyme activity are: 1) 3–4 fold capacity to absorb moisture; 2) the emulsifying and stabilizing effects; 3) the improved fat-binding with meat products and 4) the reduced fat absorption with bakery products during frying. According to the “Ernährungsbericht 1976” of the DGE, growing importance has to be paid to an increased consumption of vegetable protein sources for better nutrition.     

Composition,nutritional, and functional properties,and quality criteria of soy protein concentrates and soy protein isolates

The available commercial soy protein concentrates and soy protein isolates afford the food processor concentrated sources of protein with some interesting and varied functional properties. Each class of products is mild to bland in flavor and light in color. The concentrates contain at least 70% protein and the isolates 90%. The nutritional quality of the proteins is fair to good and can be excellent either by supplementation with 1.5% methionine or by appropriate blending with other sources of proteins. The concentrates provide the food manufacturer with products where a high protein content for unit of volume or wt is needed. The isolates are available for uses where the functional properties reside solely in the protein and the nonprotein components may interfere. The adaptability of the proteins to modification by controlled processing conditions has made it possible for the manufacturers to produce a diversity of products that should be of interest to practically all food formulators.     

Soy protein ingredients prepared by new processes—Aqueous processing and industrial membrane isolation

The production of food ingredients from undefatted soybeans by aqueous processing and isolation of protein from soy flour by ultrafiltration membranes has been demonstrated adequately during the past decade. These relatively new techniques offer significant advantages over conventional soy processing methods. Aqueous processing requires no petroleum-based solvent and consequently provides increased safety and flexibility of operation (because start-up and shutdown are safe and easy). It also provides opportunities for removal or deactivation of undesirable constituents of raw materials with appropriate water-soluble chemicals. It is, however, less efficient in oil extraction, and demulsification is required to recover clear oil when emulsions form. Ultrafiltration processes recover protein directly from soy flour extracts and thereby avoid generation of the whey which results from the conventional isoelectric precipitation. These processes have the advantages of increased isolate yield (as whey proteins are recovered in the isolate), and produce products having enhanced functionality and nitrogen solubility. The two processing techniques have subsequently been combined to obtain a single procedure with the advantages of each. Extracts from undefatted soybeans have been membrane processed with and without separating the oil to produce a variety of new soy protein ingredients.     

Meat and dairy analogs from vegetable proteins

The enormous pressures for protein food products in the coming decades, brought on by world population increases, will be solved through the extension of traditional animal protein foods with vegetable proteins and through the development of food products based on vegetable proteins alone. Analogs of beef, fish, poultry and other traditional animal protein products, which are based solely on vegetable proteins, are an established food category, and are expected to increase market share. Dairy analogs based on vegetable cow’s milk and dairy desserts. Vegetable forms of cheese and other milk protein products are also expected to increase. Nutritional equivalence of vegetable protein products is fundamental to product design. Protein and fat content must be standardized. Vegetable proteins are blended to reach desirable protein quality. Analogs currently marketed are primarily blends of soy and wheat proteins containing lesser amounts of yeast and egg albumen. The products are fortified with vitamins and minerals to levels present in animal protein foods. Processed meat manufacturing facilities, which exist in most developed countries, can be readily adapted to produce meat analogs. The technology which has been developed to date is based on soy or soy/wheat combinations. The technology can readily be adapted to other vegetable proteins such as rapeseed, cotton-seed, sesame or sunflower. These protein sources, while in abundance in many countries, need process research which can refine them for human use. The vegetable proteins offer the world’s exploding population a virtually untapped resource for its burgeoning food requirements.     

Soy flour and grits for use in food products

Processing alternatives enable the soybean processor to manufacture soy flour products which vary in fat content, granulation and degree of heat treatment. By controlling these variables, the processor is able to regulate the nutritional value and functional properties of these products. The application of soy flour products is dependent upon their functional properties, nutritional value and low cost. Currently, the major markets for soy flour and grits are in pet foods and animal feeds, cereal based foods and ingredients, meat based foods, and as a substrate for refined protein products such as the textured vegetable proteins, soy protein concentrates, isolates and hydrolysates. These soy protein products are generally marketed as functional and nutritional substitutes for meat, milk and egg protein. For example, soy flour is a functional replacement for milk in many cereal-based foods, e.g., bread, and also enhances the nutritional value of the cereal protein by supplying lysine to the formulation. The United States government has pioneered the development and marketing of protein-enriched, cereal-based foods designed to combat worldwide starvation. The government has directly supported the research and development of corn and wheat-based food substrates supplemented with soy flour, and has purchased over one billion pounds of these products since 1966 for worldwide distribution. One of 21 papers presented at the Symposium, “Oilseed Processors Challenged by World Protein Need,” ISF-AOCS World Congress, Chicago, September 1970.     

Nutritional role of soya protein for humans

This paper reviews the role played by soya protein in human nutrition on the basis of protein quality, energy and protein densities, and availability of trace minerals. The importance of supplementation with methionine was analyzed and it was concluded that there is little nutritional or public health justification for such supplementation when the intake of protein is adequate. The use of refatted soy products has good potential to increase the dietary concentrations of protein and energy, which may be particularly important for children in developing countries and for the elderly or other persons with limited dietary intakes and digestive capacity. Investigations based on chemical balance and on the use of stable isotopes indicate that the iron from soybean is well absorbed by humans, as are inorganic iron and zinc in the presence of soy protein. Soybeans and properly processed soy products have a good protein quality, and when fed in adequate amounts, they can satisfy the total nitrogen and essential amino acid needs of children and adults. Further research related to soy products should be directed mainly toward establishing their overall nutritional value as part of mixed diets or food systems, and not just assess their protein quality. Assessing the protein quality of soy products may be required when major processing modifications are made in the manufacture of soy products for human consumption. INCAP Publication #I-1145.     

Use of vegetable protein in processed seafood products

In comparison to other muscle foods like red meats, utilization of vegetable protein products in seafood is limited, and can be considered to be in its infancy. The opportunities are not predicated entirely on the future. Opportunities exist today, and vegetable protein products such as soy can and will impact on the seafood market. The opportunities for soy protein products in seafood are and will be realized in terms of nutrition, functionality, and economics. The change in price of frozen fish paste caused by the influence of the 200-mile zones was 2 to 2.5 times in one year. In contrast, the price of soy protein products has not changed during the same period. Obviously, this price difference has an important impact on the demand for soy protein products. As the price of fish in Japan has risen, consumers have tended to avoid buying fish products, and there has been a trend toward buying animal products. Consequently, the use of textured soy proteins in these animal protein foods has also increased. Japan has a long and well developed tradition of eating soybean foods, and at the same time, Japan possesses a high level of scientific technology concerned with new soy protein foods. The whole nation, including the consumers, producers, academic societies and the government, is of the consensus that soybeans are a good food source whose consumption should be encouraged and increased. In spite of such favored conditions, utilization of soy protein foods in Japan has not really taken off even after almost 20 years of development. Reasons for the slow expansion of the market are many. However, the definite factor which decisively affects the increased use seems ultimately to be a balance between the quality and price of the products. In Japan the balance would become favorable to soy protein because of the limited fish resources as well as recent advances in the technology of soy protein foods. Several formulations for fish/soy products are presented.     

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.