Using low-temperature desolventized soybean meal or concentrated soybean protein as raw materials, the principle of the lowest solubility of protein at the isoelectric point is used to obtain a uniform component through acid and alkali treatment, and a functional and specific complete protein food additive. The protein purity is required to be no less than 90%, and the main components are 7S globulin and 11S globulin.

1. Main functional characteristics of soy protein isolate

1) Emulsification

Soy protein isolate is a typical surfactant. In practical applications, it exhibits emulsification properties, which is one of the most important and basic properties of soy protein. It can simultaneously reduce the surface tension of water and air as well as water and oil to form a stable emulsion. The emulsified oil droplets can be protected by the protein on their surface, forming a stable emulsified structure. Soy protein isolate emulsifiers have been widely used in the stabilization of frozen, baked and soup products.

2) Gel properties

The soy protein isolate can be heated, dialyzed and treated to form a colloidal structure to obtain a gel. The higher the protein content, the easier it is to produce a hard gel with strong toughness and good elasticity. If the protein concentration is lower than 70%, only a soft gel can be made. In addition, the gel made with a high 11S globulin content is stronger. The soy protein isolate gel type has excellent viscosity, plasticity and elasticity. Therefore, it can not only be used as a carrier of water, but also as a carrier of various complexes such as flavoring agents and sugars, which is very beneficial for food processing.

3) Foaming

The increase in volume of soy protein during processing is called foaming. Foam is formed by a thin film of liquid surfactant soluble protein, and the bubbles are separated by elastic liquid and semi-solid membranes to prevent the bubbles from combining, thereby reducing the surface tension between air and water. Foaming requires protein molecules to enter the inner surface and quickly flatten. This property can be used to give processed foods a loose structure and a crispy taste. Degradants can be used to enhance foaming. The lower the degree of polymerization, the stronger the foaming.

4) Conjunctival

After soy protein is moderately mixed with water and then steamed under high pressure, a thin film can be formed on the surface, which is a barrier between water and the water-containing agent. The mixture of isolated protein and egg protein is applied to the surface of minced meat fiber to form a thin film, which is easy to dry, can prevent the flavor from fading, and is conducive to providing a good state for rehydration products.

2. Nutritional value of soy protein isolate

As a high-quality plant protein, soy protein isolate has a very high protein concentration, balanced nutrients, is rich in essential amino acids for the human body, and has a high digestibility in the body. Appropriate addition can improve the protein efficacy ratio of food.

Clinical studies have shown that soy protein isolate has the following health functions:

① Significantly lowers cholesterol.

② It is extremely rich in lipids and linoleic acid, which prevents cardiovascular diseases.

③ Removes excess lecithin, a type of sterol, from the blood. Foods containing soy protein isolate are suitable for people of different ages, and are a type of food that helps patients with high cholesterol, obesity, heart disease, high blood pressure, etc.

3. Application of soy protein isolate

1 ) Meat products:

Adding soy protein isolate to high-grade meat products not only improves the texture and flavor of meat products, but also increases the protein content and strengthens vitamins. Due to its strong functionality, a dosage of 2-5% can retain water and fat, prevent gravy separation, improve quality, and improve taste. Injecting protein isolate into meat pieces such as ham and then processing the meat pieces can increase the ham rate by 20%. Protein isolate is used in fried fish cakes, fish rolls or fish sausages, and can be taken with 20-40% fish meat.

2 ) Dairy products:

Soy protein isolate is used to replace milk powder, non-milk beverages and various forms of milk products. It is a food that replaces milk with complete nutrition and cholesterol-free. Soy protein isolate can be used in the production of ice cream instead of skim milk powder to improve the emulsification properties of ice cream, delay lactose crystallization and prevent the phenomenon of "sandiness".

3 ) Products made from wheat flour:

Adding no more than 5% of protein isolate when producing bread can increase the volume of the bread, improve the color of the crust, and extend the shelf life; adding 2-3% of protein isolate when processing noodles can reduce the breakage rate after boiling, increase the noodle yield, and the noodles have a good color and a taste similar to strong flour noodles.

Soy protein isolate can also be used in food industries such as beverages, nutritional foods, fermented foods, etc., and plays a unique role in improving food quality and increasing nutrition.