Soy protein concentrate is a type of protein that is made by removing water-soluble carbohydrates from defatted and dehulled soybeans. It is made up of about 70% soy protein and retains most of the fiber within the original soybean. It is usually available as an off-white powder, with bland odour and taste.
Soy protein concentrate is a widely used ingredient in food products such as baked foods and meat products. It is used in meat and poultry products to increase water and fat retention, and to improve nutritional values: e.g. increased protein. Soy protein concentrates can also be used in pet foods, and as a milk replacement product.
Soy protein concentrate can be produced via 3 major methods: Aqueous alcohol wash, acid wash, and heat denaturation/water extraction process.
Aqueous Alcohol Wash Process
This process uses aqueous solutions of lower aliphatic alcohols to extract soluble carbohydrates from defatted soy flour without solubilizing its proteins.
This process takes advantage of the pH-dependence of the solubility of soy proteins. Since soy proteins exhibit minimum solubility at pH levels of 4.2 to 4.5, sugars can be extracted while minimizing the solubilizing of proteins using acidic solutions.
Heat Denaturation/Water Extraction Process
In this process, defatted soy meals are first denatured thermally using humid heat, to render the proteins insoluble. Hot water is then used to treat the denatured meal, to dissolve and extract the water-soluble sugars within the soy flour or flakes.
Soy protein concentrate is easily digestible and suitable for use in pet foods and livestock. Most pet food products and animal diets contain soy derived products as an additional source of protein and fibers. Soy protein concentrates can also be used as aquaculture feeds.
Milk Replacement Products
The low soluble carbohydrate content and lower immunogenicity in soy protein concentrates allow it to be used in milk replacements for both humans and baby animals such as calves and pigs. The proteins are used to incorporate fat into formulations by forming fat emulsions and to provide protein for nutrition.