SOY PROTEIN PRODUCTS - PROCESSING AND USE

Soy protein products are mainly used as ingredients in formulated food s and seldom are seen by the public. They consist of four broad catego ries. (1) Most soy proteins are derived from ''white flakes,'' made by dehulling, flaking and defatting soybeans by hexane extraction. These may then be milled into defatted flours or grits containing similar t o 50-54% protein; extracted with ethanol or acidic waters to remove fl avor compounds and flatulence sugars, producing soy protein concentrat es containing 65-70% protein; or processed into soy protein isolates c ontaining 90+% protein by alkali extraction of the protein, removal of fiber by centrifugation and reprecipitation and drying of the protein . (2) Full-fat products are made in enzyme-active and in toasted forms . (3) Various dried soyfoods, including soy milk and tofu, are produce d. (4) Mixtures of soy proteins with cereals, dried milk or egg fracti ons, gelatin, stabilizers and emulsifiers are offered for specific bak ing, whipping, breading and batter applications. Texturized products, resembling meat chunks or bacon chips, are made by extrusion of flours and concentrates or spinning of isolates. Soy protein ingredients are used in compounded foods for their functional properties, including w ater and fat absorption, emulsification, aeration (whipping) and heat setting and for increasing total protein content and improving the ess ential amino acids profile.