Value-added soybean products—soy flour, textured soy protein, soy protein concentrates, and soy protein isolates, and soy milk replacer—offer improved nutrition, result in foods that have improved functional properties, and when consumed on a regular basis can be part of a program that will not only improve general health but prevent some chronic diseases including heart disease. Soy flour, soy protein concentrates, and soy protein isolates are all made from whole soybeans. Textured soy protein is made from either soy protein concentrate or soy flour.
Soy flour is made from roasted soybeans ground into a fine powder. There are three kinds of soy flour available – natural or full-fat, which contains the natural oils found in the soybean and is 50% protein; defatted, which has the oils removed during processing and is an even more concentrated source of protein than full-fat soy flour; and lecithinated, which has lecithin added to it.
All soy flour gives a protein boost to recipes. Soy flour is gluten-free, so yeast-raised breads made with soy flour have a more dense texture. It is best used for fortification of other flours, including wheat, rice, and corn. Adding up to 10% of soy flour can greatly increase the protein and nutritional content of bread, chapattis, tortilla, and Arab pita bread, which are often the principle diet and at times the only staple that poor people get in some countries. Addition of soy to wheat or corn bread increases its shelf life and delays staling. Soy flour absorbs about twice as much water as its weight. It also retards oil absorption in fried foods.
Soy Protein Concentrates
Concentrates come from defatted soy flakes and contains at least 70 percent protein. It is a highly digestible source of amino acids and retains most of the beans’ dietary fiber.
The bland flavor of soy protein concentrates makes them an ideal source of protein in many foods including dietary products, pasta, tortillas, nutritional beverages, meat analogs, and processed meat products. Concentrates can be used to improve texture and mouth feel in foods while providing an excellent source of highly digestible protein. Even a small quantity can greatly improve the nutritional content of the food they are added to.
Functional properties of food can be improved by using soy protein concentrates. Water retention in breads can be increased and act as an emulsifier and bind fats. By adding soy protein concentrate to the outside of doughnuts, less excess fat is absorbed during frying. In meat products, they act as an emulsifier and bind water causing it to be juicier and loose less weight after cooking.
Refer to the Soy Protein Concentrate Reference Guide for more information.
Soy Protein Isolates
When protein is removed from defatted flakes the result is soy protein isolate, the most highly refined soy protein. Containing 90 percent protein, isolates possess the greatest amount of protein of all soy products. They are a highly digestible source of amino acids and because of the bland taste can be added to foods without jeopardizing flavor or characteristics.
Isolates are used to add juiciness, cohesiveness, and viscosity to a variety of meat, seafood, and poultry products. This is especially true when soy is used to enhance the flavor and nutritional quality of tough meat. It also does excellent job improving the sensory attributes of whole meat products. Roasts and hams that contain soy isolates will be juicer and more nutritional. In addition, isolates are commonly used in dairy type products such as beverages, frozen desserts and invitation cheeses. They can also be used as an ingredient to supplement or replace milk powder in a variety of uses.
Refer to the Soy Protein Isolate Reference Guide for more information.
Textured Soy Protein (TSP)
Textured soy protein (TSP) usually refers to products made from textured soy flour and textured soy protein concentrates. TSP can contain between 50% and 70% protein, depending on the starting material used. TSP is most commonly used as a meat extender or analog and can be added to a meal to increase its protein content. TSP has a texture similar to ground beef or other meat products and must be rehydrated with boiling water before use. Refer to the Soy Protein Reference Guide for more information.
Textured soy flour is made by running defatted soy flour through an extrusion cooker, which allows for many different forms and sizes. It contains 50 percent protein as well as the dietary fiber and soluble carbohydrates from the soybean. When hydrated, it has a chewy texture. It is widely used as a meat extender. Often referred to simply as textured soy protein, textured soy flour is sold dried in granular and chunk style and has a bland flavor.
Textured soy protein concentrates are made by extrusion and are found in many different forms and sizes. Textured soy protein concentrates contain 70 percent protein as well as the dietary fiber from the soybean. When hydrated, they have a chewy texture and contribute to the texture of meat products.
Soy Milk Replacer
Soy Milk Replacer has 26% protein and 39% carbohydrates. It has exactly the same nutritional properties as dairy milk. The starting material is soy concentrate, and several nutrients and other ingredients are added to give it the nutritional properties of dairy milk. It provides higher benefits than dairy milk, because it is lactose free and cholesterol free. It is a different product than soy milk and has a different nutritional profile. Soy milk replacer has to be reconstituted with water at a ratio of 1:8. It has packaging and storage requirements similar to dehydrated cow’s milk.