Processed free glutamic acid is different. Used in food, dietary supplements, cosmetics, pharmaceuticals, and vaccines, it is produced commercially in manufacturing and/or chemical plants, and/or by fermentation. The glutamate in plant and animal protein is L-glutamate only. The glutamate in manufactured free glutamate contains D-glutamate as well as L-glutamate.
There are six basic methods for producing free glutamate. Glutamate can be freed from protein through autolysis, acid hydrolysis, enzymolysis (hydrolysis using enzymes), and/or fermentation of protein (2-4). Glutamate can also be produced by combining specific amino acids, reducing sugars, animal or vegetable fats or oils, and optional ingredients including hydrolyzed vegetable protein (5,13). Its products are often referred to as "processed flavors" or "reaction flavors."
These first five methods for producing free glutamate all produce glutamic acid in combination with other amino acids. Processed free glutamic acid can also be produced as a single amino acid using bacterial fermentation, a process whereby carefully selected genetically modified bacteria secrete free glutamic acid through their cell walls (6).
Today, this method of bacterial fermentation is used to produce much, if not all, of the free glutamic acid used by the pharmaceutical industry. It is also used to produce the food ingredient monosodium glutamate.
For information about carcinogenic propanols access:
The National Toxicology Program (NTP) of the National Institute of Environmental Health Sciences (NIEHS) at the National Institutes of Health (NIH) Review of Toxicological Literature, and The Codex Alimentarius Commission Position Paper on Chloropropanols.
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6. Leung A, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics. New York: Wiley, 1996: 373-375.
7. Deki M, Echizen A, Temma T. Minor components in monosodium glutamate. Kanzei Chuo Bunsekishoho.1977;17:59-62.
8. Man EH, Bada JL. Dietary D-Amino Acids. Ann Rev Nutr.1987;7:209-225.
9. Konno R, Oowada T, Ozaki A, Iida T, Niwa A, Yasumura Y, Mizutani T. Origin of D-alanine present in urine of mutant mice lacking D-amino-acid oxidase activity. Am J Physiol. 1993;265:G699-G703.
10. Sjostrom LB. Flavor potentiators. In: Furia TE, CRC Handbook of Food Additives. Cleveland: CRC Press, 1972: 513-521.
11. Rundlett KL, Armstrong DW. Evaluation of free D-glutamate in processed foods. Chirality. 1994;6:277-282.
12. Food Chemical News, Dec 2, 1996. p24-25.
13. Food Chemical News, May 31, 1993. p16.