8730. Soybean

Nomenclature

Soya bean; soja bean; Lincoln bean; Manchurian bean; Chinese pea.

Description and references

Seed of Glycine max (L.) Merrill [G. soja Sieb. & Zucc., G. hispida (Moench) Maxim., Soja hispida Moench], Leguminosae. Habit. Eastern Asia, especially Manchuria. Cultivated in the midwestern U.S.A., Brazil, some European countries, such as Italy and Yugoslavia. Constit. Proteins 40%, carbohydrates 17%, oil 18%, ash 4.6%. The ash content equals K 1.67%, Na 0.34%, Ca 0.28%, Mg 0.22%, Cl 0.024%, I 0.000054%, Fe 0.0097%, Cu 0.0012%, Mn 0.0028%, Zn 0.0022%, P 0.66%, S 0.41%, Al 0.0007%. The chief proteins are glycinin, a globulin, phaseolin, another globulin, and 2 albumins: legumelin and soy legumelin. The carbohydrates are sucrose, raffinose, stachyose, and pentosans. Phosphorus compds (about 3%) are phospholipids, nucleic acid phosphates, phytin, and inorganic phosphates. The phospholipids contain lecithin, cephalin, and inositol. The vitamin content is moderate: Vitamin A 110 i.u./100g; thiamine 1.14 mg/100 g; riboflavin 0.31 mg/100 g; niacin 2.1 mg/100 g; ascorbic acid: trace. Food energy: 350 cal/100 g. Amino acid analysis of the protein fraction: Glutamic acid 18.4%, leucine 8.1%, arginine 7.5%, lysine 6.7%, valine 5.4%, isoleucine 5.3%, phenylalanine 5.2%, threonine 3.9%, histidine 2.3%, tryptophan 1.6%, methionine 1.4%. Ten kg of soybeans yield 15 g of the isoflavone glycoside genistin, the mother liquor contains daidzin. Soybeans contain a small amount of enzymes such as lipoxidase, urease, uricase, protease, antienzymes such as antitrypsin, and a growth-inhibiting factor. Bitter principles and saponins are also found. Reviews: K. S. Markley, Soybeans and Soybean Products, 2 vols. (Interscience, New York, 1951); Cowan in Kirk-Othmer Encyclopedia of Chemical Technology vol. 18 (Interscience, New York, 2nd ed., 1969) pp 599-614.

Properties

Whitish or yellowish-green to brownish-black, ovoid beans, about 8 mm long, 7 mm wide, and 6 mm thick. Most varieties have a wt of 20 g/100 seeds.

Use

In the production of soybean oil. As food and feedstuff. Debittered soybean flour contains practically no starch and is widely used in dietetic foods. Soybean meal obtained after expressing the oil is a preferred source of protein for feedstuffs. Other products are soybean lecithin, genistin, monosodium glutamate, soybean milk, soy sauce; tofu, a soybean curd; miso, a fermented mixture with barley or rice; natto, which is soybean cheese. Soybean proteins are used also in the adhesive and plastics industries.

Therapeutic Category

Nutrient.