Name: Monosodium Glutamate
CAS No: Glutamic acid monosodium salt monohydrate [142-47-2]
USP-NF: Monosodium Glutamate
Chinese seasoning; E621; glutamic acid monosodium salt; glutamic acid, sodium salt; MSG; monosodium L-glutamate monohydrate; natrii glutamas; sodium L-glutamate; sodium glutamate monohydrate; sodium hydrogen L-(þ)-2-aminoglutarate monohydrate.
Glutamic acid monosodium salt monohydrate [142-47-2]
C5H8NO4Na 169.13 (anhydrous) C5H8NO4NaH2O 187.13 (monohydrate)
Monosodium glutamate is used in oral pharmaceutical formulations as a buffer and a flavor enhancer. For example, it is used with sugar to improve the palatability of bitter-tasting drugs and can reduce the metallic taste of iron-containing liquids. It has also been used in subcutaneous live vaccine injections such as measles, mumps, rubella and varicella-zoster live vaccine (ProQuad). However, the most widespread use of monosodium glutamate is as a flavor enhancer in food products. Typically, 0.2–0.9% is used in normally salted foods, although products such as soy protein can contain 10–30%. The use of monosodium glutamate in food products has been controversial owing to the apparently high number of adverse reactions attributed to the substance, which gives rise to the so-called ‘Chinese Restaurant Syndrome’ The current consensus is that there is no clinically compelling evidence to suggest that monosodium glutamate may be harmful at the current levels used in foods.
Monosodium glutamate occurs as white free-flowing crystals or a crystalline powder. It is practically odorless and has a meat-like taste.
See Table 1
Acidity/alkalinity pH = 7.0 (0.2% w/v aqueous solution) Melting point 2328C Solubility Soluble in water; sparingly soluble in ethanol (95%). Specific rotation [a]D 25 = þ24.28 to þ25.58 at 258C (8.0% w/v in 1.0 N HCl).
Aqueous solutions of monosodium glutamate may be sterilized by autoclaving. Monosodium glutamate should be stored in a tight container in a cool, dry place.
Monosodium glutamate is the monosodium salt of the naturally occurring L-form of glutamic acid. It is commonly manufactured by fermentation of carbohydrate sources such as sugar beet molasses. In general, sugar beet products are used in Europe and the USA.Other carbohydrate sources such as sugar cane and tapioca are used in Asia.
Monosodium glutamate is widely used in foods and oral pharmaceutical formulations. It is generally regarded as moderately toxic on ingestion or intravenous administration. Adverse effects include somnolence, hallucinations and distorted perceptions, headache, dyspnea, nausea or vomiting, and dermatitis. The lowest lethal oral dose in humans is reported to be 43 mg/kg.(1) The use of monosodium glutamate in foods has been controversial due to the so-called ‘Chinese Restaurant Syndrome’ (see Section 18), although it is generally regarded as safe at intake levels of up to 6 mg/kg bodyweight.(2) In Europe, total glutamate intake from food ranges from 5–12 g/day.(2) There has been a report of a foreign body granuloma caused by monosodium glutamate after a BCG vaccination.(3)
Observe normal precautions appropriate to the circumstances and quantity of material handled. When heated to decomposition, monosodium glutamate emits toxic fumes of NOx and Na2O
GRAS listed. Accepted in Europe for use as a food additive in certain applications. Included in the FDA Inactive Ingredients Database (oral syrup). Included in nonparenteral medicines licensed in the UK. Included in subcutaneous vaccine injections
Monosodium glutamate has been associated with reports of adverse reactions termed ‘Chinese Restaurant Syndrome’ after it was first self-reported by a physician who regularly experienced numbness and palpitations after consuming Chinese food.(4) Subsequent to this first report, numerous other anecdotal reports of adverse reactions to monosodium glutamate were made, with symptoms occurring at doses of 1.5–12 g. Reactions include paresthesias or a skin burning sensation, facial pressure or tightness sensation, and substernal chest pressure. Severity of reaction corresponded with increased dose. Reports of ‘Chinese Restaurant Syndrome’ in children are rare. A variety of other adverse reactions to monosodium glutamate have also been reported including flushing, asthma, headache, behavioral abnormalities, and ventricular tachycardia.(5–7) Placebo-controlled, blinded, trials of monosodium glutamate consumption have, however, largely failed to reproduce the full effects of ‘Chinese Restaurant Syndrome’ as it was originally described, and symptoms may be simply due to dyspepsia.(8) Some dose-dependent adverse reactions may be attributed to monosodium glutamate, with doses of 5 g producing reactions in 30% of individuals tested.(9) In the USA, the FDA has stated that monosodium glutamate and related substances are safe food ingredients for most people when used at ‘customary’ levels.(10–12) Monosodium glutamate monohydrate 32 g is approximately equivalent to anhydrous monosodium glutamate 29 g or glutamic acid 25 g. Each gram of monosodium glutamate monohydrate represents 5.3 mmol (5.3 mEq) of sodium. A specification for monosodium glutamate is contained in the Food Chemicals Codex (FCC).(13) The EINECS number for monosodium glutamate is 205-538-1. The PubChem Compound ID (CID) for monosodium glutamate is 23689119