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.     

Soy protein products in other foods

Both long-term and emerging patterns of utilization underscore the diversity of the use of soy protein products in processed foods other than meat foods. The purpose of this paper is to present a selective overview of this diverse usage.     

Authorizations and restrictions on soy protein in foods in the U.S.

The Food and Drug Administration makes the basic decisions on what materials will be permitted in U.S. foods. The U.S. Department of Agriculture then selects those items which it will allow in meats and poultry products. The Food and Drug Administration is in the process of developing definitions for soy products and issuing the regulatory controls over their uses. Care is being taken not to impose burdensome regulatory restrictions on a technology that is in a rapid state of development.     

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.     

Requirements for foods containing soy protein in the food for peace program

Under the Food for Peace Program, whole grains, milled wheat flour, milled rice, soybean oil, soybean flour, nonfat dry milk, soyacontaining blended food supplements, and soya-fortified processed foods are provided by the U.S. to needy people abroad to alleviate malnutrition. These commodities are used in maternal/child health programs, school feeding, food for work projects and disaster relief. The wide diversity of nutritional requirements and traditional food preferences has led to development of nine soya-containing food types, which are used in the PL-480 Title II donation program as blended food supplements or fortified processed foods. Research studies have led to the development of product specifications. Blended food supplements include the standardized mixtures of corn-soya-milk (CSM), instant CSM, wheat-soy blend and whey-soy drink mix. These foods, developed to fulfill the nutritional requirements of preschool children, contain from 17.5 to 29.7% either toasted-defatted or equivalent full-fat soya flour, along with vitamins and minerals. In addition, 4–19% soya oil is added to improve caloric density. These products contain 19 or 20% minimum protein and 6 or 19% minimum fat content. Fortified processed foods include soya-fortified bulgur (SFB), soya-fortified bread wheat flour (SFWF), soya-fortified cornmeal (SFCM), soya-fortified sorghum grits (SFSG), and soya-fortified rolled oats (SFRO). These foods contain toasted soya flour, grits, or flakes added at 12–15% levels. Fortified foods are generally consumed by people other than infants.     

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.     

Effects of dietary casein and soy protein on metabolism of radiolabelled low density apolipoprotein B in rabbits

Rabbits fed semipurified diets containing casein have elevated plasma cholesterol levels compared to those fed soy protein. As part of continuing studies on the mechanism of casein-induced hypercholesterolemia, two groups of six rabbits were fed these diets for 14 to 16 weeks. Animals fed the casein diet were found to have significantly higher plasma concentrations of protein, cholesterol, triacylglycerol, phospholipid and apolipoprotein B (apo B) associated with low density lipoprotein (LDL) than those fed the soy protein diet. Kinetic studies showed that the fractional catabolic rate of LDL-apo B was significantly lower in animals fed casein than in those fed soy protein regardless of whether the tracer LDL was obtained from donors fed casein or soy protein. The production rate of LDL-apo B was higher in casein-fed animals but this was not statistically significant. These results show that the efficiency of removal of LDL is significantly reduced in animals fed casein compared to those fed soy protein, and that the source of LDL did not affect the efficiency of its subsequent removal. The acumulation of LDL in casein-fed animals is consistent with down-regulation of the LDL receptor.     

Nutritional value and economic aspects of fortification of foods of plant origin with soy protein

The protein requirements of children and adults are reviewed in comparison with the protein qualities of several foods with and without added soy. The economic considerations greatly favor soy containing foods for equivalent nutrition.     

Interaction between dietary protein and fat in triglyceride metabolism in the rat: Effects of soy protein and menhaden oil

The objective of the present study was to determine the mechanisms by which dietary proteins interact with dietary lipids in the regulation of triglyceridemia in rats. Male Sprague-Dawley rats (n=56) were subjected to 28-d experimental diets containing different combinations of proteins (20% w/w) and lipid sources (14% w/w): (i) casein-menhaden oil, (ii) casein-beef tallow, (iii) soy protein-menhaden oil, and (iv) soy protein-beef tallow. Significant protein-lipid interactions were observed on triglyceridemia and hepatic cholesterol in fasted rats. The combination of casein and beef tallow was associated with high plasma TG and hepatic cholesterol concentrations, which were reduced by substitution either of soy for casein or of menhaden oil for beef tallow. Therefore, triglyceridemia and liver cholesterol remained low with soy protein feeding, independently of the lipid source, as well as with menhaden oil feeding, regardless of the protein source. The menhaden oil diets reduced plasma cholesterol, hepatic TG, and TG secretion compared with beef tallow diets independently of the dietary protein source. Modifying the source of dietary proteins and lipids had no effect on post-heparin plasma lipoprotein lipase activity. These results demonstrate that soy protein can lower rat triglyceridemia relative to casein when associated with beef tallow consumption, whereas menhaden oil can attenuate hypertriglyceridemia when rats are fed casein. The data further suggest that part of the hypotriglyceridemic effect of soy protein in the rat may be mediated by reduced hepatic lipid synthesis, as is the case for menhaden oil.     

Uses of soy protein in mixed protein systems to meet nutritional needs

Soya products can be introduced into animal protein food systems to supplement animal protein. This can serve to increase the total protein available to target populations. Nutritional studies have demonstrated that mixtures of soya protein and meat or soya protein and fish are of a biological quality similar to that of meat or fish protein when fed alone. Soya products also can be used in mixed protein systems with vegetable proteins to complement amino acids. Many studies with human subjects have demonstrated the utility of soya products in a variety of soya-cereal foods that can serve as the major source of protein for infants and children.     

The dietary fiber fraction in raw and processed foods

The purpose of the present study was to estimate dietary fiber components in raw vegetables and processed by different methods. Samples of 8 raw, 15 boiled, 5 fermented, 5 fried and 2 canned vegetables were analyzed. Results indicated the sample vegetables after being boiled, canned, fermented and fried, presented alterations in the dietary fiber insoluble and soluble components, e.i., by interaction or solubility tending to an increase or decrease of its components. Results obtained in the dietary fiber components of processed vegetables, in the sample analyzed, presented variations among them with the different processing techniques.     

Position of soy protein processors in relation to laws and regulations

Soy protein products in the U.S. fall under the regulatory powers of the Food and Drug Administration as far as processing plants are concerned. The U.S. Department of Agriculture controls their use in meat and poultry products. Many states have separate regulations. The industry is expected to know federal and state regulations and interpret them for the customer. Difficulties arise for the processor when there are so many different state, Food and Drug Administration, U.S. Department of Agriculture, and foreign regulations that affect the products. This Conference might spearhead world-wide cooperation in the development of future regulations.     

Enzymatic hydrolysis and fermentation of soy flour to produce ethanol and soy protein concentrate with increased polyphenols

There is a need to effectively concentrate soy protein from defatted soy flour (DSF) while simultaneously valorizing the carbohydrate-rich byproduct, which would otherwise be a waste. This study aims to evaluate a process developed to produce soy protein concentrates (SPC) by substantially hydrolyzing carbohydrates from DSF with the help of enzymes into water-soluble saccharides and monomeric sugars, which were simultaneously utilized by Saccharomyces cerevisiae for fermentation into ethanol. The enzyme mixture consisted of cellulase, pectinase, and $\mathrm{\alpha }$-galactosidase blend. The effect of process time on SPC, overall protein recovery, carbohydrate hydrolysis, yeast growth, ethanol concentration, and total polyphenol concentration (TPC) of SPC and hydrolysate was evaluated. Control and enzymes-only (EO) systems were maintained in conjunction with the enzymes + yeast (EY) system to individually assess the impact of isoelectric precipitation of soy proteins and enzymatic hydrolysis of carbohydrates without yeasts. After 12.25 h of EY process, 100 g of dry DSF produced 68.45 g dry SPC containing $72.23\pm 0.25$% protein and 384 ml hydrolysate containing $9.76\pm 0.05$ mg/ml ethanol. Flatulence-causing raffinose-series-oligosaccharides (RSOs) were completely hydrolyzed. Soluble carbohydrates in the EY treatment were consistently lower than in the control and EO treatment. TPC of SPC prepared by EY treatment increased by 2.5 times compared to the control. Thus, this novel process successfully produced a high-protein SPC with hydrolyzed RSOs, lower insoluble carbohydrates, high TPC, and a coproduct ethanol.     

Future developments in soy protein research and technology

The many successful and desirable uses of soy products have been recounted in the talks during the past three days. We will attempt to emphasize: (A.) That practically every natural food can be improved in its adaptation to food for man. This includes milk. Improvement may be made by deleting certain undesirable factors such as flavors, odor, or anti-nutritional factors. We will attempt to point out that many of these undesirable factors have been recognized and either eliminated or reduced to insignificance. We also will point out that further improvement may be made by enhancing functional and nutritional characteristics; (B.) That acceptance of soybean products as desired food constituents can result in further improvement in both yield and quality of the basic product as well as of the flours, concentrates, and isolates, which in turn may result in more economical production and processing costs; (C.) That the best progress is accomplished by those who recognize the inherent problems in the products and who are honestly willing to do something about them. It is the responsibility of every processor of food products, in the U.S. and elsewhere, to produce food products worthy of the quality of the raw product from which they are produced. This is particularly true of soybeans. The observance of all these factors will result in a real contribution to the food industry throughout the world.     

Effects of interactions between soy protein isolate and pectin on properties of soy protein-based films

Composite films in coacervation condition offer an alternative to change properties of protein-based films, and they present potential applications such as inclusion, stabilization, and release of bioactive compounds in foods. Maximum interactions between soy protein isolate (SPI) (5%) and high methoxyl pectin (PEC) (0.5, 1, 1.5, and 2%), by zeta potential analysis, are found at a pH of 3. The transparency of the SPI films is lost at this pH. When PEC is added to SPI films, the elasticity, solubility, and permeability to water vapor are not significantly altered, but the tensile strength increases. Permeabilities to oxygen are higher for low PEC contents, but as PEC is added, their values are typical of SPI films produced at a pH of 11. A homogeneous structure is found at the higher PEC concentrations. The interactions of PEC–SPI can be useful to tailor films and coatings for applications such as to carry and protect substances of interest. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48732.     

Effect of soy oil supplementation and protein level in laying hen diets on praecaecal nutrient digestibility,performance, reproductive performance,fatty acid composition of yolk fat,and on other egg quality parameters

An experiment was carried out with laying hens in the age of 22—45 weeks to examine the effects of added soy oil (0%, 3.5%, 7%, 10.5%, and 14%) and dietary protein level (13.2% and 16.3%) on laying and reproductive performance, fatty acid composition of yolk fat, and other egg quality parameters. Moreover, digestibility of nutrients and of energy was determined by using a marker technique. Laying intensity and feed intake were not influenced by dietary treatments whereas egg weight and daily egg mass production were significantly improved by soy oil addition in a non‐linear related manner. The feed conversion ratio reached a minimum at soy oil proportions between 3.5% and 10.5%. Reproductive performance in terms of fertilized eggs, hatchability, and mortality of chicks was not affected by dietary treatments. The increase of egg weights due to soy oil addition was accompanied by a simultaneous increase in the proportion of albumen and a decrease of yolk and shell percentage. Palmitic acid (C16:0) and oleic acid (C18:1) proportions in yolk fat decreased as soy oil addition was increased whereas the proportions of linoleic acid (C18:2 n‐6), linolenic acid (C18:3 n‐3), and docosahexaenoic acid (C22:6 n‐3) were increased at the same time. Praecaecal digestibility of crude fat and fatty acids of the diets were non‐linearly improved by soy oil addition. Digestibility of crude protein and amino acids were not affected by either protein content of the diet or by soy oil supplementation. In conclusion, a decrease in dietary protein content from 16.3% to 13.2% did not negatively influence performance of hens and egg quality under the experimental conditions applied. Soy oil addition improved egg quality.     

Conjugated linoleic acid (CLA) isomers: formation,analysis, amounts in foods,and dietary intake

The analysis, content, and daily intake of conjugated linoleic acid isomers (CLA) are presented in the following review. Modern analytical techniques such as capillary gas chromatography (GC), silverion high performance liquid chromatography (Ag⁺-HPLC) combined with different detection methods (flame ionisation, mass spectroscopic, ultra violet) are mandatory for the unequivocal determination of geometric and positional CLA isomers. An overview is given on the CLA contents in 139 German foods, e. g. milk/dairy products, meat/meat products, edible oils, margarines, fish, and deep fried products. The dietary intake for men and women is estimated using consumption data.