Monosodium glutamate

This article is about the chemical compound. For its use in food, see glutamate flavoring. For glutamic acid in general, see glutamic acid.
For other uses of "MSG", see MSG (disambiguation).
Monosodium glutamate
Chemical composition of monosodium glutamate
Structure of monosodium glutamate
Crystalline monosodium glutamate
Names
IUPAC name
Sodium 2-aminopentanedioate
Identifiers
142-47-2 YesY
3D model (Jmol) Interactive image
ChemSpider 76943 YesY
ECHA InfoCard 100.005.035
EC Number 205-538-1
E number E621 (flavour enhancer)
PubChem 85314
UNII C3C196L9FG YesY
Properties
C5H8NO4Na
Molar mass 169.111 g/mol
Appearance White crystalline powder
Melting point 232 °C (450 °F; 505 K)
740 g/L
Hazards
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 0: Exposure under fire conditions would offer no hazard beyond that of ordinary combustible material. E.g., sodium chloride Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
0
0
0
Lethal dose or concentration (LD, LC):
15800 mg/kg (oral, rat)[Gov. 1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Monosodium glutamate (MSG, also known as sodium glutamate) is the sodium salt of glutamic acid, one of the most abundant naturally occurring non-essential amino acids.[Manuf. 1] Monosodium glutamate is found naturally in tomatoes, cheese and other foods.[1]

MSG is used in the food industry as a flavor enhancer with an umami taste that intensifies the meaty, savory flavor of food, as naturally occurring glutamate does in foods such as stews and meat soups.[2][3] It was first prepared in 1908 by Japanese biochemist Kikunae Ikeda, who was trying to isolate and duplicate the savory taste of kombu, an edible seaweed used as a base for many Japanese soups. MSG as a flavor enhancer balances, blends, and rounds the perception of other tastes.[4][5]

The U.S. Food and Drug Administration has given MSG its generally recognized as safe (GRAS) designation.[Gov. 2] A popular belief is that large doses of MSG can cause headaches and other feelings of discomfort, known as "Chinese restaurant syndrome," but double-blind tests fail to find evidence of such a reaction.[Gov. 2][6] The European Union classifies it as a food additive permitted in certain foods and subject to quantitative limits. MSG has the HS code 29224220 and the E number E621.[Gov. 3]

Use

Pure MSG is reported not to have a pleasant taste until it is combined with a savory aroma.[Manuf. 2] The basic sensory function of MSG is attributed to its ability to enhance savory taste-active compounds when added in the proper concentration.[4] The optimum concentration varies by food; in clear soup, the pleasure score rapidly falls with the addition of more than one gram of MSG per 100 mL.[7]

The sodium content (in mass percent) of MSG, 12%, is about one-third of that in sodium chloride (39%), due to the greater mass of the glutamate counterion.[Manuf. 3] Although other salts of glutamate have been used in low-salt soups, they are less palatable than MSG.[Manuf. 4]

Safety

A popular belief is that MSG can cause headaches and other feelings of discomfort, but double-blind tests fail to find evidence of such a reaction.[6] MSG has been used for more than 100 years to season food, with a number of studies conducted on its safety. Consumption and manufacture of high-salt and high-glutamate foods, which contain both sodium and glutamate, stretch back far longer, with evidence of cheese manufacture as early as 5,500 BC.[8] International and national bodies governing food additives currently consider MSG safe for human consumption as a flavor enhancer.[Gov. 4] Under normal conditions, humans can metabolize relatively large quantities of glutamate, which is naturally produced in the gut in the course of protein hydrolysis. The median lethal dose (LD50) is between 15 and 18 g/kg body weight in rats and mice, respectively, five times greater than the LD50 of salt (3 g/kg in rats). The use of MSG as a food additive and the natural level of glutamic acid in foods are not toxicological concerns in humans.[Gov. 4]

A 1995 report from the Federation of American Societies for Experimental Biology (FASEB) for the United States Food and Drug Administration (FDA) concluded that MSG is safe when "eaten at customary levels" and, although a subgroup of otherwise-healthy individuals develop an MSG symptom complex when exposed to 3 g of MSG in the absence of food, MSG as a cause has not been established because the symptom reports are anecdotal.[9]

According to the report, no data support the role of glutamate in chronic disease. A controlled, double-blind, multiple-location clinical trial failed to demonstrate a relationship between the MSG symptom complex and actual MSG consumption. No statistical association has been demonstrated, and the few responses were inconsistent. No symptoms were observed when MSG was administered with food.[10][11][12][13]

Adequately controlling for experimental bias includes a double-blind, placebo-controlled experimental design (DBPC) and administration by capsule, because of the unique aftertaste of glutamates.[12] In a study by Tarasoff and Kelly (1993), 71 fasting participants were given 5 g of MSG and then a standard breakfast. One reaction (to the placebo, in a self-identified MSG-sensitive individual) occurred.[10] A study by Geha et al. (2000) tested the reaction of 130 subjects with a reported sensitivity to MSG. Multiple DBPC trials were performed, with subjects exhibiting at least two symptoms continuing. Two people out of the 130 responded to all four challenges. Because of the low prevalence, the researchers concluded that a response to MSG was not reproducible.[14]

Studies exploring MSG's role in obesity have yielded mixed results.[15][16]

Although several studies have investigated anecdotal links between MSG and asthma, current evidence does not support a causal association.[17] Since glutamates are important neurotransmitters in the human brain, playing a key role in learning and memory, ongoing neurological studies indicate a need for further research.[18]

Chinese restaurant syndrome

A hypothetical MSG symptom complex, named "Chinese restaurant syndrome", attracted attention in the period after 1968, when Robert Ho Man Kwok reported symptoms he felt after an American-Chinese meal. Kwok suggested possible reasons for his symptoms, including alcohol (from cooking with wine), sodium, and MSG; however, a number of symptoms have become associated with MSG.[10]

Food Standards Australia New Zealand (FSANZ) MSG technical report concludes, "There is no convincing evidence that MSG is a significant factor in causing systemic reactions resulting in severe illness or mortality. The studies conducted to date on Chinese restaurant syndrome (CRS) have largely failed to demonstrate a causal association with MSG. Symptoms resembling those of CRS may be provoked in a clinical setting in small numbers of individuals by the administration of large doses of MSG without food. However, such effects are neither persistent nor serious and are likely to be attenuated when MSG is consumed with food. In terms of more serious adverse effects such as the triggering of bronchospasm in asthmatic individuals, the evidence does not indicate that MSG is a significant trigger factor."[Gov. 5][Gov. 6]

However, the FSANZ MSG report says that although no data are available on average MSG consumption in Australia and New Zealand, "data from the United Kingdom indicates an average intake of 590 mg/day, with extreme users (97.5th percentile consumers) consuming 2330 mg/day." (Rhodes et al. 1991) In a highly seasoned restaurant meal, intakes as high as 5000 mg or more may be possible (Yang et al. 1997). When very large doses of MSG (>5 g MSG in a bolus dose) are ingested, plasma glutamate concentration will significantly increase. However, the concentration typically returns to normal within two hours. In general, foods providing metabolizable carbohydrate significantly attenuate peak plasma glutamate levels at doses up to 150 mg/kg body weight. Two earlier studies—the 1987 Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the 1995 Federation of American Societies for Experimental Biology (FASEB)—concluded, "there may be a small number of unstable asthmatics who respond to doses of 1.5 – 2.5g of MSG in the absence of food." The FASEB evaluation concluded, "sufficient evidence exists to indicate some individuals may experience manifestations of CRS when exposed to a ≥3g bolus dose of MSG in the absence of food."[Gov. 5]

Production

MSG has been produced by three methods: hydrolysis of vegetable proteins with hydrochloric acid to disrupt peptide bonds (1909–1962); direct chemical synthesis with acrylonitrile (1962–1973), and bacterial fermentation (the current method).[Manuf. 5] Wheat gluten was originally used for hydrolysis because it contains more than 30 g of glutamate and glutamine in 100 g of protein. As demand for MSG increased, chemical synthesis and fermentation were studied. The polyacrylic fiber industry began in Japan during the mid-1950s, and acrylonitrile was adopted as a base material to synthesize MSG.[Manuf. 6]

Currently (2016), most global MSG is produced by bacterial fermentation in a process similar to making vinegar or yogurt. Sodium is added later, for neutralization. During fermentation, Corynebacterium species, cultured with ammonia and carbohydrates from sugar beets, sugar cane, tapioca or molasses, excrete amino acids into a culture broth from which L-glutamate is isolated. The Kyowa Hakko Kogyo Company developed industrial fermentation to produce L-glutamate.[Manuf. 7]

The conversion yield and production rate (from sugars to glutamate) continues to improve in the industrial production of MSG, keeping up with demand.[Manuf. 5] The product, after filtration, concentration, acidification, and crystallization, is glutamate, sodium, and water.

Chemical properties

MSG is freely soluble in water, but it is not hygroscopic and is insoluble in common organic solvents (such as ether).[19] It is generally stable under food-processing conditions. MSG does not break down during cooking and, like other amino acids, will exhibit a Maillard reaction (browning) in the presence of sugars at very high temperatures.[Manuf. 8] A white, odorless, crystalline powder, in solution it dissociates into glutamate and sodium ions.

History

Glutamic acid was discovered and identified in 1866 by the German chemist Karl Heinrich Ritthausen, who treated wheat gluten (for which it was named) with sulfuric acid.[20] Kikunae Ikeda of Tokyo Imperial University isolated glutamic acid as a taste substance in 1908 from the seaweed Laminaria japonica (kombu) by aqueous extraction and crystallization, calling its taste umami.[Manuf. 9] Ikeda noticed that dashi, the Japanese broth of katsuobushi and kombu, had a unique taste not yet scientifically described (not sweet, salty, sour, or bitter).[Manuf. 9] To verify that ionized glutamate was responsible for umami, he studied the taste properties of glutamate salts: calcium, potassium, ammonium, and magnesium glutamate. All these salts elicited umami and a metallic taste due to the other minerals. Of them, sodium glutamate was the most soluble and palatable and the easiest to crystallize. Ikeda called his product "monosodium glutamate", and submitted a patent to produce MSG;[Gov. 7] the Suzuki brothers began commercial production of MSG in 1909 as Aji-no-moto (味の素, "essence of taste").[Manuf. 5][Manuf. 8][21]

Society and culture

It has been suggested that a fear of MSG may reflect anti-Asian racism, with MSG being seen as an "Oriental", alien arrival in Western cooking, likely to be dangerous.[22][23][24] Food critic Jeffrey Steingarten argued that fear of MSG should be seen as a Western-centric mindset, lacking awareness of its common use in Far Eastern cooking without apparent problems: "If MSG is a problem, why doesn't everyone in China have a headache?"[25][26]

Regulations

United States

MSG is one of several forms of glutamic acid found in foods, in large part because glutamic acid (an amino acid) is pervasive in nature. Glutamic acid and its salts may be present in a variety of other additives, including hydrolyzed vegetable protein, autolyzed yeast, hydrolyzed yeast, yeast extract, soy extracts, and protein isolate, which must be specifically labeled. Since 1998, MSG cannot be included in the term "spices and flavorings". The ribonucleotide food additives disodium inosinate and disodium guanylate are usually used with monosodium glutamate-containing ingredients. However, the term "natural flavor" is used by the food industry for glutamic acid (chemically similar to MSG, lacking only the sodium ion). The Food and Drug Administration does not require disclosure of components and amounts of "natural flavor."[Gov. 8]

The FDA considers labels such as "no MSG" or "no added MSG" misleading if the food has ingredients which are sources of free glutamate, such as hydrolyzed protein. In 1993, it proposed adding "contains glutamate" to the common names of certain hydrolyzed proteins with substantial amounts of glutamate.

Australia and New Zealand

Standard 1.2.4 of the Australia and New Zealand Food Standards Code requires MSG to be labeled in packaged foods. The label must have the food-additive class name (e.g. "flavour enhancer"), followed by the name of the additive ("MSG") or its International Numbering System (INS) number, 621.[Gov. 9]

Names

The following are alternative names for MSG:[Gov. 1][Manuf. 10][Manuf. 11]

Chemical names and identifiers

Trade names

See also

References

Government

  1. 1 2 "Monosodium glutamate NF". NLM.NIH.gov. U.S. National Library of Medicine, ChemIDplus. Retrieved August 11, 2014.
  2. 1 2 "Questions and Answers on Monosodium glutamate (MSG)". U.S. Food and Drug Administration. November 19, 2012. Retrieved February 4, 2014.
  3. ↑ "Current EU approved additives and their E Numbers". Food.gov.uk. 2010-11-26. Retrieved 2012-01-30.
  4. 1 2 Walker R, Lupien JR, School of Biological Sciences, University of Surrey, UK, and Food and Nutrition Division, FAO of the United Nations, Italy. (April 2000). "The safety evaluation of monosodium glutamate". Journal of Nutrition. 130 (4S Suppl): 1049S–52S. PMID 10736380.
  5. 1 2 "MONOSODIUM GLUTAMATE, A Safety Assessment, TECHNICAL REPORT SERIES NO. 20". FoodStandards.gov.au. Food Standards Australia New Zealand, Health Minister Chair, Peter Dutton MP. June 2003. ISBN 0642345201. ISSN 1448-3017. Retrieved January 17, 2015.
  6. ↑ "Monosodium glutamate search". FoodStandards.gov.au. Food Standards Australia New Zealand, Health Minister Chair, Peter Dutton MP. Retrieved August 13, 2014.
  7. ↑ Ikeda K (1908). "A production method of seasoning mainly consists of salt of L-glutamic acid". Japanese Patent 14804.
  8. ↑ "CFR – Code of Federal Regulations Title 21, Vol 6, Part 501, Subpart B—Specific Animal Food Labeling Requirements". FDA.gov. U.S. Food and Drug Administration. Retrieved August 13, 2014.
  9. ↑ "Standard 1.2.4 Labelling of Ingredients". Food Standards Code. Food Standards Australia New Zealand. Archived from the original on 2010-08-21. Retrieved May 15, 2010.

Manufacturers and suppliers

  1. ↑ Ninomiya K, Technical Committee , Umami Manufacturers Association of Japan (1998). "Natural occurrence". Food Reviews International. 14 (2 & 3): 177–211. doi:10.1080/87559129809541157.
  2. ↑ Rolls, Edmund T., Oxford Centre for Computational Neuroscience, United Kingdom, Supported by the Medical Research Council and in part by the International Glutamate Technical Committee, a nongovernmental organization funded by industrial producers and users of glutamate in food. (September 2009). "Functional neuroimaging of umami taste: what makes umami pleasant?". The American Journal of Clinical Nutrition. 90 (3): 804S–813S. doi:10.3945/ajcn.2009.27462R. PMID 19571217.
  3. ↑ Yamaguchi, Shizuko, Central Research Laboratories, Ajinomoto Co., Japan; Takahashi, Chikahito, Central Research Laboratories, Ajinomoto Co., Japan. (January 1984). "Interactions of monosodium glutamate and sodium chloride on saltiness and palatability of a clear soup". Journal of Food Science. 49 (1): 82?85. doi:10.1111/j.1365-2621.1984.tb13675.x.
  4. ↑ Ball P, Woodward D, Beard T, Shoobridge A, Ferrier M. Sponsorship: We acknowledge the financial support of the International Glutamate Technical Committee (IGTC), a nongovernmental organization funded by industrial producers and users of glutamate in food. (June 2002). "Calcium diglutamate improves taste characteristics of lower-salt soup". Eur J Clin Nutr. 56 (6): 519–23. doi:10.1038/sj.ejcn.1601343. PMID 12032651.
  5. 1 2 3 Sano, Chiaki, Technology and Engineering Center, Ajinomoto Co, Japan. (September 2009). "History of glutamate production". The American Journal of Clinical Nutrition. 90 (3): 728S–732S. doi:10.3945/ajcn.2009.27462F. PMID 19640955.
  6. ↑ Yoshida T, Ajinomoto Co., Planning and Development Department, Japan. (1970). "Industrial manufacture of optically active glutamic acid through total synthesis". Chem Ing Tech. 42 (9–10): 641?644. doi:10.1002/cite.330420912.
  7. ↑ Kinoshita Shukuo, Tokyo Research Laboratory, Kyowa Fermentation Industry Company; Udaka, Shigezo; Shimamoto, Masakazu. (1957). "Studies on amino acid fermentation. Part I. Production of L-glutamic acid by various microorganisms". J Gen Appl Microbiol. 3 (3): 193?205. doi:10.2323/jgam.3.193.
  8. 1 2 Yamaguchi, Shizuko, Tokyo University of Agriculture, Japan; Ninomiya, Kumiko, Technical Committee, Umami Manufacturers Association of Japan. (1998). "What is umami?". Food Reviews International. 14 (2 & 3): 123?138. doi:10.1080/87559129809541155.
  9. 1 2 Lindemann, Bernd, Universität des Saarlandes, Medical Faculty, Physiology, Germany; Ogiwara Yoko, Ajinomoto Co., Inc., European Head Office, France; Ninomiya, Yuzo, Section Oral Function and Neurobiology, Department of Regulatory Oral Science, Kyushu University Graduate School, Japan. (November 2002). "The discovery of umami". Chem Senses. 27 (9): 843–4. doi:10.1093/chemse/27.9.843. PMID 12438211.
  10. ↑ Singh, K. K.; Desai, Pinakin, Director. "Glutamate Chemical". TriveniInterChem.com. Riveni InterChem of Triveni Chemicals, manufacturer & supplier of industrial chemicals, India. Retrieved August 11, 2014.
  11. ↑ Desmo Exports Limited, Chemical Manfacturers and Importers of India (2011). "Monosodium Glutamate (MSG)". DesmoExports.com. Desmo Exports. Retrieved August 11, 2014.
  12. ↑ "Accent Flavor Enhancer". AccentFlavor.com. B&G Foods, Inc. Retrieved August 11, 2014.
  13. ↑ "B&G Foods, Incorporated". Grocery.com. Retrieved August 13, 2014.
  14. ↑ "Monosodium glutamate(MSG)". Umami Global Website. AJINOMOTO CO., INC. Retrieved 30 Oct 2016.
  15. ↑ "To Greet the Next 100 Years (Corporate Guide)" (PDF). AJINOMOTO CO.,INC. Retrieved 13 Aug 2014.

Other

  1. ↑ "FDA Q&A on MSG". fda.gov. Retrieved 5 March 2016.
  2. ↑ Ikeda K (November 2002). "New seasonings". Chem Senses. 27 (9): 847–849. doi:10.1093/chemse/27.9.847. PMID 12438213.
  3. ↑ Hayward, Tim. "OMG I love MSG". Financial Times. Nikkei. Retrieved 5 March 2016.
  4. 1 2 Loliger J (April 2000). "Function and importance of Glutamate for Savory Foods". Journal of Nutrition. 130 (4s Suppl): 915s–920s. PMID 10736352.
  5. ↑ Yamaguchi S (May 1991). "Basic properties of umami and effects on humans". Physiology & Behavior. 49 (5): 833–841. doi:10.1016/0031-9384(91)90192-Q. PMID 1679557.
  6. 1 2 Obayashi, Y; Nagamura, Y (17 May 2016). "Does monosodium glutamate really cause headache? : a systematic review of human studies". The Journal of Headache and Pain. 17: 54. doi:10.1186/s10194-016-0639-4. PMC 4870486Freely accessible. PMID 27189588.
  7. ↑ Kawamura Y, Kare MR, eds. (1987). Umami: a basic taste. New York, NY: Marcel Dekker Inc.
  8. ↑ "Art of cheese-making is 7,500 years old". Nature. December 12, 2012.
  9. ↑ Raiten DJ, Talbot JM, Fisher KD (1996). "Executive Summary from the Report: Analysis of Adverse Reactions to Monosodium Glutamate (MSG) --no summary available, 8/11/2014.". Journal of Nutrition. 126 (6): 2891S–2906S. PMID 7472671.
  10. 1 2 3 Freeman, Matthew, CNP, mph, Clinical Instructor (Adult Nurse Practitioner), Ohio State University. He reviewed 40 years of documents on PubMed, Medline, Lexis-Nexus, and Infotrac, and concluded there is no consistent clinical data to support the belief that MSG can elicit a headache, and there is no consistent evidence to suggest that individuals may be uniquely sensitive to MSG. (2006). "Reconsidering the effects of monosodium glutamate: A literature review". Journal of the American Academy of Nurse Practitioners. 18 (10): 482–6. doi:10.1111/j.1745-7599.2006.00160.x. PMID 16999713.
  11. ↑ 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.
  12. 1 2 Tarasoff L.; Kelly M.F. (1993). "Monosodium L-glutamate: a double-blind study and review". Food Chem. Toxicol. 31 (12): 1019–35. doi:10.1016/0278-6915(93)90012-N. PMID 8282275.
  13. ↑ Walker R (October 1999). "The significance of excursions above the ADI. Case study: monosodium glutamate". Regul. Toxicol. Pharmacol. 30 (2 Pt 2): S119–21. doi:10.1006/rtph.1999.1337. PMID 10597625.
  14. ↑ Williams, A. N.; Woessner, K.M. (2009). "Monosodium glutamate 'allergy': menace or myth?". Clinical & Experimental Allergy. 39 (5): 640?646. doi:10.1111/j.1365-2222.2009.03221.x.
  15. ↑ Shi, Z; Luscombe-Marsh, ND; Wittert, GA; Yuan, B; Dai, Y; Pan, X; Taylor, AW (2010). "Monosodium glutamate is not associated with obesity or a greater prevalence of weight gain over 5 years: Findings from the Jiangsu Nutrition Study of Chinese adults". The British journal of nutrition. 104 (3): 457–63. doi:10.1017/S0007114510000760. PMID 20370941.
  16. ↑ Nicholas bakalar (August 25, 2008). "Nutrition: MSG Use Is Linked to Obesity". The New York Times. Retrieved 2010-11-10. Consumption of monosodium glutamate, or MSG, the widely used food additive, may increase the likelihood of being overweight, a new study says.
  17. ↑ Stevenson, D. D. (2000). "Monosodium glutamate and asthma". J. Nutr. 130 (4S Suppl): 1067S–73S. PMID 10736384.
  18. ↑ Nicholas J. Maragakis, MD; Jeffrey D. Rothstein, MD (March 2001). "Glutamate Transporters in Neurologic Disease". 58 (3). pp. 365–370. Retrieved 2015-01-17.
  19. ↑ Win. C., ed. (1995). Principles of Biochemistry. Boston, MA: Brown Pub Co.
  20. ↑ R.H.A. Plimmer (1912) [1908]. R.H.A. Plimmer; F.G. Hopkins, eds. The Chemical Constitution of the Protein. Monographs on biochemistry. Part I. Analysis (2nd ed.). London: Longmans, Green and Co. p. 114. Retrieved June 3, 2012.
  21. ↑ Kurihara K (September 2009). "Glutamate: from discovery as a food flavor to role as a basic taste (umami)?". The American Journal of Clinical Nutrition. 90 (3): 719S–722S. doi:10.3945/ajcn.2009.27462D. PMID 19640953.
  22. ↑ Mahoney, John. "The Notorious MSG's Unlikely Formula For Success". BuzzFeed. Retrieved 12 November 2014.
  23. ↑ Dickerman, Sarah. "Could MSG make a comeback?". Slate magazine.
  24. ↑ Ibanga, Imaeyen. "China food scare: a dash of racism". ABC News. Retrieved 12 November 2014.
  25. ↑ Haber, Barbara. "Life on the Culinary Edge". Harvard Magazine. Retrieved 12 November 2014.
  26. ↑ Renton, Alex. "If MSG is so bad for you, why doesn't everyone in Asia have a headache?". The Guardian. Retrieved 12 November 2014.
  27. ↑ Sazon Seasoning : Substitutes, Ingredients, Equivalents. GourmetSleuth. Retrieved on 2016-11-04.

External links

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