Glutaminsure

BeschreibungL-Glutamic acid, or L-2-aminopentanedioic acid, is a naturally occurring amino acid of plant and animal proteins. It has a very faint odor reminiscent of yeast or freshly baked bread. It has a mild, somewhat sweet, meat-like taste.The average glutamic acid content of food proteins is 20 percent. Expressed as glutamic acid per 100 g of the edible portions, medium fat beef contains about 2.65 g of glutamic acid; whole liquid cow milk, 0.82 g; lean pork, 2.16 g; haddock, 2.32 g; peas, 5.58 g; soybeans, 7.01 g; commeal, 1.62 g; and whole grain wheat flour, 4.16 g. In addition, free glutamic acid is present in many vegetables, fish, and meats in small amounts (0. 005 to 0.23 g per 100 g) and as high as 2 g per 100 g in some varieties of cheese. Recent estimates of free amino acids in the milk of various species indicated that the free glutamic acid in human milk is about 0.22 g per 100 mL.Glutamic acid and its salts are prepared commercially by hydrolysis of gluten (wheat, corn, soybean, sugarbeet protein); by fermentation from glucose-containing raw materials; the racemic acid may be resolved into the d- and ι-isomer by fractional crystallization; from 2 -cyclopentenylamine; by microbial conversion of aketoglutaric acid; or by an alternative method, using Bacillus megatherium-cereus; from fumaric acid using B. pumilus; from starch.Glutamic acid and the hydrochloride as well as the mono-sodium, -potassium, and -ammonium salts of L-glutamic acid share similar physical properties: they are nearly odorless, white, free-flowing crystalline powders, and except for glutamic acid and glutamic acid hydrochloride, are freely soluble in water. Glutamic acid is slightly soluble and glutamic acid hydrochloride moderately soluble in water. The pH of a saturated solution is about 3.2.

OccurrenceReported as occurring in many vegetable proteins, in beef fbrin, in the chrysalis of silkworm, in the hydro- lysate of crystalline insulin Also present in other important peptides, such as glutathione, tyrocidin, folic acid, β-lactoglobulin, secretin and bacitracin, and in growth hormone

VerwendenL-glutamic acid or its salt, monosodium glutamate (MSG), is used as an additive to human food to enhance the taste. Although seaweed had been used in Asia to enhance food flavor for over 1000 years, it was not until 1908 that the essential component responsible for the flavor phenomenon was identified as glutamic acid. From 1910 until 1956, monosodium glutamate was extracted from sea weed, a slow and costly method. In 1956, Ajinomoto, a Japanese company, succeeded in producing glutamic acid by means of fermentation. Today, L-glutamic acid or MSG is generally made by microbial fermentation using genetically modified bacteria.