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Monosodium Glutamate

Monosodium Glutamate on Wikipedia:

This article is about the chemical compound. For its use in food flavouring and health concerns, see glutamic acid (flavor). For glutamic acid in general, see glutamic acid. Monosodium glutamate IUPAC name Sodium (2S)-2-amino-5-hydroxy-5-oxo-pentanoate Identifiers CAS number 142-47-2 Y PubChem 85314 ChemSpider 76943 EC-number 205-538-1 SMILES   C(CC(=O)O)C(C(=O)[O-])N.[Na+] Properties Molecular formula C5H8NNaO4 Molar mass 169.111 g/mol Appearance white crystalline powder Melting point

225 Â°C, 498 K, 437 Â°F

Solubility in water 74g/100mL  Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 Â°C, 100 kPa) Infobox references Crystalline monosodium glutamate

Monosodium glutamate, also known as sodium glutamate and MSG, is a sodium salt of the naturally occurring non-essential amino acid glutamic acid. It is used as a food additive and is commonly marketed as a flavour enhancer. It has the HS code 29224220 and the E number E621. Trade names of monosodium glutamate include Ajinomoto, Vetsin, and Accent. It was once predominantly made from wheat gluten, but is now mostly made from bacterial fermentation; it is acceptable for celiacs following a gluten-free diet.[1][2][3][4]

Although traditional Asian cuisine had often used seaweed extract, which contains high concentrations of glutamic acid, it was not until 1907 that MSG was isolated by Kikunae Ikeda. MSG was subsequently patented by Ajinomoto Corporation of Japan in 1909. In its pure form, it appears as a white crystalline powder which rapidly dissociates into sodium cations and glutamate anions on contact with water (glutamate is the anionic form of glutamic acid).


Production and chemical properties

MSG is normally obtained by the fermentation of carbohydrates, using bacterial or yeast species from genera such as Brevibacterium, Arthrobacter, Microbacterium, and Corynebacterium. Yields of 100 g/litre[citation needed] can be prepared in this way. From 1909 to the mid 1960s, MSG was prepared by the hydrolysis of wheat gluten, which is roughly 25% glutamic acid. Glutamic acid is one of the least soluble amino acids, which facilitates its purification.[5]

Like the sodium salts of other amino acids, MSG is a stable colourless solid that is degraded by strong oxidizing agents. It exists as a pair of mirror image stereoisomers (enantiomers), but only the naturally occurring L-glutamate form is used as a flavour enhancer.


The Ajinomoto company was formed to manufacture and market MSG in Japan; the name 'Aji no moto' translates to ``essence of taste``. It was introduced to the United States in 1947 as Ac'cent flavor enhancer.[6]

Modern commercial MSG is produced by fermentation[7] of starch, sugar beets, sugar cane, or molasses. About 1.5 million tonnes were sold in 2001, with 4% annual growth expected.[8] MSG is used commercially as a flavour enhancer. Although once associated with foods in Chinese restaurants, MSG is now used by most fast food chains and in many foodstuffs, particularly processed foods.[9]

Examples include:

Prepared stocks often known as stock cubes or bouillon cubes. Condiments such as barbecue sauce and salad dressings. Canned, frozen, or dried prepared food Common snack foods such as flavoured jerky, flavoured potato chips and flavoured tortilla chips. Seasoning mixtures

Only the L-glutamate enantiomer has flavour-enhancing properties.[10] Manufactured MSG contains over 99.6% of the naturally predominant L-glutamate form, which is a higher proportion of L-glutamate than found in the free glutamate ions of naturally occurring foods. Fermented products such as soy sauce, steak sauce, and Worcestershire sauce have levels of glutamate similar to foods with added MSG. However, glutamate in these brewed products may have 5% or more of the D-enantiomer.[10]

Health concerns

Main article: Glutamic acid (flavor)#Research into health effects

MSG as a food ingredient has been the subject of health studies. A report from the Federation of American Societies for Experimental Biology (FASEB) compiled in 1995 on behalf of the United States Food and Drug Administration (FDA) concluded that MSG was safe for most people when ``eaten at customary levels``. However, it also said that, based on anecdotal reports, some people may have an MSG intolerance which causes ``MSG symptom complex`` and/or a worsening of asthmatic symptoms.[11] Subsequent research found that while large doses of MSG given without food may elicit more symptoms than a placebo in individuals who believe that they react adversely to MSG, the frequency of the responses was low and the responses reported were inconsistent, not reproducible, and were not observed when MSG was given with food.[12] While many people believe that MSG is the cause of these symptoms, a statistical association has not been demonstrated under controlled conditions, even in studies with people who were convinced that they were sensitive to it.[12][13][14][15] Adequately controlling for experimental bias includes a placebo-controlled double-blinded experimental design and the application in capsules because of the strong and unique after-taste of glutamates.[13]

United States

Monosodium glutamate is one of several forms of glutamic acid found in foods, in large part because glutamic acid is pervasive in nature, being an amino acid. Glutamic acid and its salts can also be present in a wide variety of other additives, including hydrolyzed vegetable proteins, autolyzed yeast, hydrolyzed yeast, yeast extract, soy extracts, and protein isolate, which must be labelled with these common and usual names. Since 1998, these cannot be included in the term ``spices and flavorings``. The FDA considers labels such as ``No MSG`` or ``No Added MSG`` to be misleading if the food contains ingredients that are sources of free glutamate, such as hydrolyzed protein. The food additives disodium inosinate and disodium guanylate, which are nucleic acids, are usually used as substitutes for monosodium glutamate-containing ingredients.

In 1993, the FDA proposed adding the phrase ``(contains glutamate)`` to the common or usual names of certain protein hydrolysates that contain substantial amounts of glutamate.

In the 2004 version of his book, On Food and Cooking, food scientist Harold McGee states that ``[after many studies], toxicologists have concluded that MSG is a harmless ingredient for most people, even in large amounts``.


The INTERMAP Cooperative Research Group conducted a study of 752 healthy Chinese (48.7% women), age 40–59 years, randomly sampled from three rural villages in north and south China and determined that MSG intake may be positively correlated to an increased Body Mass Index (BMI).[16]

Australia and New Zealand

Standard 1.2.4 of the Australia and New Zealand Food Standards Code requires the presence of MSG as a food additive to be labeled. The label must bear the food additive class name (e.g. flavour enhancer), followed by either the name of the food additive, MSG, or its International Numbering System (INS) number, 621.

See also

Food portal Ajinomoto Co., Inc. Umami Excitotoxicity Flavour enhancer Disodium glutamate List of food additives Yeast extract


^ ^ Leung, Albert Y.; Foster, Steven (August 2003). ``Monosodium Glutamate``. Encyclopedia of Common Natural Ingredients: Used in Food, Drugs, and Cosmetics (2nd ed.). New York: Wiley. pp. 373–375. ISBN 978-0-471-47128-8. ``Monosodium glutamate can generally be produced by three methods: (1) hydrolysis of proteins such as gluten or proteins present in sugar beet wastes, (2) synthesis, and (3) microbial fermentation. In the hydrolysis method, the protein is hydrolyzed with a strong mineral acid to free amino acids, and the glutamic acid is then separated from the mixture, purified, and converted to its monosodium salt, [monosodium glutamate]. This used to be the major method of [monosodium glutamate] manufacture. Currently most of the world production of [monosodium glutamate] is by bacterial fermentation. In this method bacteria (especially strains of Micrococcus glutamicus) are grown aerobically in a liquid nutrient medium containing a carbon source (e.g., dextrose or citrate), a nitrogen source such as ammonium ions or urea, and mineral ions and growth factors. The bacteria selected for this process have the ability to excrete glutamic acid they synthesize outside of their cell membrane into the medium and accumulate there. The glutamic acid is separated from the fermentation broth by filtration, concentration, acidification, and crystallization, followed by conversion to its monosodium salt [monosodium glutamate].``.  ^ ^ ^ Kawakita, Tetsuya; Sano, Chiaki; Shioya, Shigeru; Takehara, Masahiro; Yamaguchi, Shizuko (2005). ``Monosodium Glutamate``. Ullmann’s Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a16 711.  ^ Sand, Jordan (2005). ``A Short History of MSG``. Gastronomica 5 (4): pp. 38–49. doi:10.1525/gfc.2005.5.4.38.  ^ ``Production process``. Encyclopedia of Amino Acids. Anjimoto Co., Inc.  ^ ^ Moskin, Julia (2008-03-05). ``Yes, MSG, the Secret Behind the Savor``. New York Times.  ^ a b Rundlett, Kimber L; Armstrong, Daniel W (1994). ``Evaluation of free D-glutamate in processed foods``. Chirality 6 (4): pp. 277–282. doi:10.1002/chir.530060410. PMID 7915127.  ^ ^ a b Geha RS, Beiser A, Ren C, et al. (April 2000). ``Review of alleged reaction to monosodium glutamate and outcome of a multicenter double-blind placebo-controlled study``. J. Nutr. 130 (4S Suppl): 1058S–62S. PMID 10736382.  ^ a b Tarasoff L., Kelly M.F. (1993). ``Monosodium L-glutamate: a double-blind study and review``. Food Chem. Toxicol. 31 (12): 1019–1035. doi:10.1016/0278-6915(93)90012-N. PMID 8282275.  ^ Freeman M. (October 2006). ``Reconsidering the effects of monosodium glutamate: a literature review``. J Am Acad Nurse Pract 18 (10): 482–6. doi:10.1111/j.1745-7599.2006.00160.x. PMID 16999713.  ^ Walker R (October 1999). ``The significance of excursions above the ADI. Case study: monosodium glutamate``. Regul. Toxicol. Pharmacol. 30 (2 Pt 2): S119–S121. doi:10.1006/rtph.1999.1337. PMID 10597625.  ^ He, Ka; Zhao, Liancheng; Daviglus, Martha L; Dyer, Alan R; Van Horn, Linda; Garside, Daniel; Zhu, Linguang; Dongshuang, Guo; Wu, Yangfeng; Zhou, Beifan; Stamler, Jeremiah (August 2008). ``Association of monosodium glutamate intake with overweight in Chinese adults: the INTERMAP Study``. Obesity (The Obesity Society) 16 (8): pp. 1875–1880. doi:10.1038/oby.2008.274. PMID 18497735. 

External links

Monosodium glutamate: Is it harmful? (Mayo Clinic)