Soy protein
Dehulled and defatted soybeans are processed into three kinds of high protein commercial products: soy flour, concentrates, and isolates.
[1] Upon germination of the soybean, the protein will be digested, and the released amino acids will be transported to locations of seedling growth.
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.
At the start of World War II, Glidden sent a sample of Julian's isolated soy (alpha) protein to National Foam System Inc. (today a unit of Kidde Fire Fighting) which used it to develop Aero-Foam,[5][6] used by the United States Navy for firefighting and referred to as "bean soup".
While not exactly the brainchild of Dr. Julian, it was the meticulous care given to the preparation of the soy protein that made the fire fighting foam possible.
When a hydrolysate of isolated soy protein was fed into a water stream, the mixture was converted into a foam by means of an aerating nozzle.
The soy protein foam was used to smother oil and gasoline fires aboard ships, and was particularly useful on aircraft carriers.
[7] In 1958, Central Soya of Fort Wayne, Indiana, acquired Julian's Soy Products Division (Chemurgy) of the Glidden Paint Company, Chicago.
Specific applications include adhesives, asphalts, resins, cleaning materials, cosmetics, inks, pleather, paints, paper coatings, pesticides/fungicides, plastics, polyesters, and textile fibres.
[18]: 11 Soy isolates are mainly used to improve the texture of meat products, but are also used to increase protein content, to enhance moisture retention, and as an emulsifier.
This method was found to be flawed for the biological evaluation of protein quality because the young rats used in the study had higher relative requirements for sulfur-containing amino acids than did humans.
Although there is only preclinical evidence for a possible mechanism, the meta-analysis report stated that soy phytoestrogens – the isoflavones, genistein and daidzein – may be involved in reducing serum cholesterol levels.
"[37] In 2012, the European Food Safety Authority (EFSA) published a scientific opinion on isolated soy proteins and reduction of blood LDL-cholesterol concentrations.
[38] EFSA concluded that a cause and effect relationship was not established between the consumption of soy protein and a reduction in blood LDL-cholesterol concentrations.
[42] 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) from dehulled and defatted soybeans that have undergone only a minimal heat treatment so the protein is close to being native or undenatured.
For the 11S protein, glycinin, to fold properly into its hexagonal shape (containing six subunits, a hexamer), it must undergo a very limited proteolysis[44][45][46] in a manner similar to the cleavage of a peptide from proinsulin to obtain active insulin.
The dough is extruded through a die into various possible shapes: granules, flakes, chunks, goulash, steakettes (schnitzel), etc., and dried in an oven.
The extrusion technology changes the structure of the soy protein, resulting in a fibrous, spongy matrix similar in texture to meat.
[47][48] Food service, retail and institutional (primarily school lunch and correctional) facilities regularly use such "extended" products.
The soy-based meat substitute textured vegetable protein has been used for more than 50 years as a way of inexpensively and safely extending ground beef up to 30% for hamburgers, without reducing its nutritional value.
