Abstract: Soy protein is rich in 8 essential human base acids and does not contain cholesterol. It has incomparable functional properties of animal protein. Its application in the production of traditional soy products can improve the processing methods and edible characteristics of traditional soy products. The application status of soy protein in traditional soy products (beans, dried tofu, soy sauce) is discussed, and its application in traditional soy products is prospected.

Keywords: traditional soy products, soy protein isolate, soy protein concentrate

Related products for this article: Soy protein products

Soy protein is a high-quality plant protein, and its nutritional and health-care value is well known. Following the approval of the U.S. Food and Drug Administration (FDA) on October 26, 1999, the health statement of soy protein, that is, “daily intake of low-fat and low-cholesterol foods containing 25g of soy protein can significantly reduce the risk of heart disease. Since “risk”, soy protein and its products have become the research and development hotspot of many food institutions. my country has a long history of edible soybeans. There are many types of traditional soybean products, but they have the disadvantages of inconvenient processing and heavy beany flavor. The application of soybean protein to traditional soybean products can not only enhance the edible characteristics, but also reduce production costs, facilitate processing and shorten processing. Process. Soy protein has been applied to a variety of traditional soy products.

This article briefly introduces the classification of soy protein, and analyzes the characteristics of different soy protein. The application of different soy protein properties in traditional soy products such as tofu, dried tofu, soy sauce, and yuba was discussed.

According to GB/T 20371-2006 “Soy Protein for Food Industry”, soy protein can be divided into soybean meal (50%～65%), soybean protein concentrate (65%～90%), soybean protein isolate (>90%) due to different protein content. %)3 types. Soy protein is a mixed system of multiple proteins. According to the results of ultracentrifugation analysis, soy protein can be divided into 4 components: 2S, 7S, 11S, and 15S. The protein composition of soy flour is the most complete, followed by soy protein concentrate. Soy protein isolate is relatively missing, mainly due to different processing techniques. Different soy proteins have different functions.

1.1 Soy flour

Soy flour is generally divided into defatted soybean protein powder, low-fat soybean protein powder and full-fat soybean protein powder according to the difference in fat content. The process is defatted soybean meal, defatted soybean meal and dehulled soybean crushing. Residual solvents, poor functionality, and a small range of applications in traditional soy products.

1.2 Soy protein concentrate

There are two main production methods for soybean protein concentrate, alcohol concentration and acid concentration. Soy protein concentrate has good gelling and emulsifying properties, and strong water and oil retention function. Soy protein concentrate is rich in dietary fiber and has good water absorption. Both the alcohol method and the acid method mainly remove the oligosaccharides and soluble fibers in the low-temperature soybean meal, and at the same time remove most of the 2S small molecule protein, so it has functions such as gelation and emulsification compared with soybean meal. Greatly improved.

1.3 Soy protein isolate

Soy protein isolate is a refined soybean protein product obtained by using low-temperature soybean meal as raw material through alkali-dissolving and acid precipitation. Soy protein isolate has good solubility, emulsification, foaming, water retention, oil retention and viscoelasticity. It is widely used in meat products, dairy products, cold drinks, baked goods and health food industries.

Soy protein isolate is divided into three types according to different functional properties: rolling gel type, meat injection type and dispersed brewing type.

2.1 Application of soy protein in tofu

As a traditional food, tofu has a history of more than 2,000 years and is rich in nutritional value. The traditional processing technology of tofu is: soybean→selection→soaking→refining→filtering→boiling→mixing→squatting→squeezing and forming. The production cycle of traditional tofu is long, about 4-6 hours; it is difficult to control microorganisms and has a short shelf life; it is fragile, and its cooking characteristics need to be improved.

With the application of soy protein isolate in the food field, using the characteristics of gelatinity and water holding capacity of soy protein isolate, Chiba tofu made from soy protein isolate as the main material has been developed in the market. The processing technology is to add soy protein isolate, soybean oil and starch and other ingredients and water into the chopping pot, chopping, serving and forming, and steaming. The processing technology is simple, the production cycle is short, and it takes 1 to 2 hours. The effects of time, temperature, lactone and transglutaminase addition on the gel strength of tofu were studied, and the production process of Chiba tofu was optimized. The optimal process conditions of Qianye Tofu were determined as TG enzyme content 0.3%, salad oil and soybean protein isolate mass ratio 3:5, soybean protein isolate and water mass ratio 1:5, cooking temperature 90℃.

In addition, the soybean protein isolate was added to the soy milk slurry, and the yield, quality and microstructure of tofu after the addition of soybean protein isolate were analyzed. The results show that the yield of tofu is higher when the addition amount of soy protein isolate is 1%. With the increase of the addition amount of soybean protein isolate, the yield gradually decreases; the water retention of tofu has been significantly improved, and the addition amount is 2% When soy protein isolate is added, the viscosity and elasticity of tofu first decrease, and then gradually increase; but the hardness and toughness of tofu decrease with the increase of soy protein isolate; in addition, soybean The addition of protein isolate makes the microstructure of tofu change significantly.

Applying soy protein isolate to the field of tofu can not only improve the hardness and water retention of tofu, remove the odor of tofu, but also increase the palatability of tofu, increase the way tofu is eaten in food, provide essential protein, and make up for vegetarian products. The lack of low protein content.

2.2 Application of soy protein in dried tofu

Dried tofu has the reputation of “plant meat”. It is rich in protein, fat, carbohydrates, calcium, phosphorus, iron and other essential nutrients for the human body. It has the advantages of balanced nutrition and easy digestion and absorption by the human body. Dried tofu is entering the scale After chemical production, the traditional process of making tofu with soybeans as raw materials and then making dried tofu has become increasingly unsuitable for market demand. Based on the Chiba tofu made with soy protein isolate, the production process of soy protein tofu has been applied and favored by major manufacturers. This kind of dried bean curd has simple processing technology, low microbial control difficulty, safer and healthier. Domestic well-known tofu brands are committed to applying the new tofu processing technology based on soy protein isolate and soy protein concentrate, and tofu made from soy tissue protein has entered the market.

2.3 Application of soy protein in soy sauce

The traditional brewing process of soy sauce is based on soybean or soybean meal and other vegetable protein as the main raw material, supplemented by starchy raw materials such as flour, wheat, bran, etc., after microbial fermentation, the product contains a variety of amino acids and has a special color and fragrance. , Flavored condiments. Using soybean protein isolate as raw material, the application of soybean protein isolate with different enzymolysis degrees in the preparation of soy sauce was studied. Firstly, the process parameters of enzymatic hydrolysis of soy protein isolate were determined by single factor experiment, and then the quality of soy sauce prepared by adding different degrees of enzymatic hydrolysis of soy protein isolate was studied. The research results showed that the enzymatic hydrolysis temperature was 50℃ and pH was 7.0. , The proteolysis product of soybean separation under the condition of enzymolysis time of 5 h is most suitable for the preparation of soy sauce.

To develop functional soy sauce from soybean peptides obtained by enzymatic hydrolysis with soybean protein isolate as raw material. Comprehensive analysis from multiple perspectives such as theory, practical operation and market research, it is concluded that the functional soy sauce is operability and practical development significance. It has broad market prospects, which is of reference significance for manufacturers to develop new products and quickly seize market share.

2.4 Application of soy protein in yuba

Yuba is a food made from soybean as raw material, soaked, refined, filtered, boiled, stretched, and dried. Yuba is a product of a certain structure composed of soybean protein film and fat. It has high nutritional value, easy to store and convenient to eat.

This paper introduces a foreign method for producing yuba using defatted soy protein. This method is simple to operate and easy to control. It is an advanced method for early application of soybean protein to produce yuba. Using soybean protein isolate and soybean oil as raw materials, artificially simulated soybean milk system was used to conduct film-forming experiments to study the influence of protein content, lipid content, protein denaturation degree and protein components on the film formation of yuba. Research results show that the increase in lipid content can increase the film formation speed, increase membrane elasticity, and increase the protein and fat content of the film. However, excessive lipid content will have a certain inhibitory effect on the above indicators. As the amount of soy protein isolate increases, the film formation speed will increase, the hardness of the membrane will increase, the protein content of the membrane will increase, and the lipid content of the membrane will first increase and then decrease. The increased degree of protein denaturation can increase the film formation speed and improve the mechanical properties and nutritional value of the film. Although the change of protein composition has little effect on the film formation speed, the 11S/7S ratio directly affects the mechanical properties of the membrane. The higher the 11S/7S ratio, the better the mechanical properties of the membrane.

Soy protein isolate and soybean protein concentrate have more and more advantages in the production of yuba due to their excellent gel and film-forming properties. At the same time, in the process of producing soy protein isolate and soy protein concentrate, the beany smell is removed through the flash evaporation process, which provides favorable conditions for improving the flavor of yuba and lays a foundation for export to European and American countries.