English

Noun

monosodium

1. (in combination) one atom of sodium in a compound

Derived terms

• monosodium glutamate
• monosodium methyl arsenate

Monosodium glutamate (commonly known as MSG) is a sodium salt of glutamic acid, a non-essential amino acid. It is used as a food additive and is commonly marketed as a "flavour enhancer". Alternative names include:

• sodium glutamate, flavour enhancer 621
• 2-aminoglutaric acid
• 2-aminopentanedioic acid
• MSG
• E number: E621
• HS code: 29224220

Trade names include Ajinomoto, Vetsin, or Accent.

Although traditional Asian cuisine uses flavour-enhancing ingredients which contain high concentrations of MSG, it was not isolated until 1907. MSG was subsequently patented by the Japanese Ajinomoto Corporation in 1909. In its pure form, it appears as a white crystalline powder; when dissolved in water (or saliva) it rapidly dissociates into sodium cations and glutamate anions (glutamate is the anionic form of glutamic acid, a naturally occurring amino acid).

Chemical properties

Under standard conditions for temperature and pressure, MSG is stable, but it reacts with strong oxidizing agents. Two chiral enantiomers exist for monosodium glutamate, but only the naturally occurring L-glutamate form is used as a flavour enhancer.

Commercialization

The Ajinomoto company was formed to manufacture and market MSG in Japan; the name 'Ajinomoto' means "essence of taste". It was introduced to the United States in 1947 as Ac'cent flavor enhancer.

Modern commercial MSG is produced by fermentation of starch, sugar beets, sugar cane, or molasses. About 1.5 million metric tons were sold in 2001, with 4% annual growth expected. MSG is used commercially as a flavour enhancer. Although once stereotypically associated with foods in Chinese restaurants, it is now found in many common food items, particularly processed foods. Examples include:

• Canned soups.
• Pre-prepared stocks often known as stock cubes.
• Condiments such as barbecue sauce.
• Frozen dinners.
• Frozen seafood.
• Common snack foods such as flavored potato chips and flavored tortilla chips.
• Most fast food.
• Instant meals such as the seasoning mixtures for instant noodles.

Only the L-glutamate enantiomer has flavour-enhancing properties. 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 like soy sauce, steak sauce, and Worcestershire sauce have comparable levels of glutamate as foods with added MSG. However, glutamate in these brewed products may be composed 5% or more of the D-enantiomer.

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

Australia and New Zealand

Standard 1.2.4 of the Australia 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 (eg. flavour enhancer), followed by either the name of the food additive (eg MSG) or its International Numbering System (INS) number (eg 621).

See also

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

References

External Links

• FDA: No long-term hazard
• msgtruth.org