Soy protein concentrate

Soy protein is a protein that is isolated from soybean. It is made from soybean meal that has been dehulled and defatted. Dehulled and defatted soybeans are processed into three kinds of high protein commercial products : soy flour, concentrates, and isolates. Soy protein isolate has been used since 1959 in foods for its functional properties. Recently, soy protein popularity has increased due to its use in health food products, and many countries allow health claims for foods rich in soy protein.

Soy protein is generally regarded as being concentrated in protein bodies, which are estimated to contain at least 60–70% of the total soybean protein. Upon germination of the soybean, the protein will be digested, and the released amino acids will be transported to locations of seedling growth. Soybeans contain a small but newly very significant 2S Albumin storage protein. Legume proteins, such as soy and pulses, belong to the globulin family of seed storage proteins called legumin and vicilins, or in the case of soybeans, glycinin and beta-conglycinin. Soybeans also contain biologically active or metabolic proteins, such as enzymes, trypsin inhibitors, hemagglutinins, and cysteine proteases very similar to papain. The soy cotyledon storage proteins, important for human nutrition, can be extracted most efficiently by water, water plus dilute alkali (pH 7–9), or aqueous solutions of sodium chloride (0.5–2 M ≈ 30-120 g/l) from dehulled and defatted soybeans that have undergone only a minimal heat treatment so the protein is close to being native or undenatured.

Soy protein has been available since 1936 for its functional properties. In that year, organic chemist Percy Lavon Julian designed the world's first plant for the isolation of industrial-grade soy protein called alpha protein. The largest use of industrial-grade protein was, and still is, for paper coatings, in which it serves as a pigment binder. However, Julian's plant must have also been the source of the "soy protein isolate" which Ford's Robert Boyer and Frank Calvert spun into an artificial silk that was then tailored into that now famous "silk is soy" suit that Henry Ford wore on special occasions. The plant's eventual daily output of 40 tons of soy protein isolate made the Soya Products Division into Glidden's most profitable division.

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