General Description
White or off-white crystalline powder with a slight peptone-like odor. pH (0.2% solution)7.0.
Reactivity Profile
MONOSODIUM GLUTAMATE(142-47-2) is an amide. Amides/imides react with azo and diazo compounds to generate toxic gases. Flammable gases are formed by the reaction of organic amides/imides with strong reducing agents. Amides are very weak bases (weaker than water). Imides are less basic yet and in fact react with strong bases to form salts. That is, they can react as acids. Mixing amides with dehydrating agents such as P2O5 or SOCl2 generates the corresponding nitrile. The combustion of these compounds generates mixed oxides of nitrogen (NOx).
Air & Water Reactions
Water soluble.
Fire Hazard
Flash point data are not available for this chemical, but MONOSODIUM GLUTAMATE is probably combustible.
Chemical Properties
Colorless powder
Chemical Properties
Monosodium glutamate occurs as white free-flowing crystals or a
crystalline powder. It is practically odorless and has a meat-like
taste.
Chemical Properties
Monosodium glutamate, the best-known and most widely used flavor enhancer, is practically odorless and may have
either a slightly sweet or slightly salty taste. Addition of monosodium glutamate to food enhances several specific flavor characteristics, such as impact, body of fullness, continuity, mouth fullness, mildness and complexity. For a detailed description of this
compound refer to Burdock (1997)
Occurrence
Reported found in certain seaweeds including Laminaria japonica
Definition
ChEBI: An optically active form of monosodium glutamate having L-configuration.
Preparation
Monosodium glutamate is commonly produced by a fermentation process using glucose (often sugar molasses) as a
starting substance. Once the glucose is converted to glutamic acid, it is filtered, dissolved and converted to monosodium glutamate
by neutralization with sodium hydroxide. The monosodium glutamate solution is decolorized and then crystallized, dried, sieved,
packed and shipped
Production Methods
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.
M
452 Monosodium Glutamate Other carbohydrate sources such as sugar cane and tapioca are used
in Asia.
Pharmaceutical Applications
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.
Biochem/physiol Actions
Monosodium glutamate?(MSG) is a food additive and an environmental agent, that can affect inflammation.
Safety
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.The use of
monosodium glutamate in foods has been controversial due to the
so-called ‘Chinese Restaurant Syndrome’, although
it is generally regarded as safe at intake levels of up to 6 mg/kg bodyweight.In Europe, total glutamate intake from food ranges from
5–12 g/day.
There has been a report of a foreign body granuloma caused by
monosodium glutamate after a BCG vaccination.
Environmental Fate
MSG is a white, odorless powder with high water solubility. If
released into the air, it remains in the particulate phase until
removed by deposition.
storage
Aqueous solutions of monosodium glutamate may be sterilized by
autoclaving. Monosodium glutamate should be stored in a tight
container in a cool, dry place.
Toxicity evaluation
Although several mechanisms have been proposed to be
responsible for causing CRS, none has been extensively studied.
One hypothesis has been that the effects are due to an immediate
hypersensitivity reaction. Since no immunoglobulin E
(IgE)-mediated reaction has been documented, there is no
direct evidence that this is the case. Another hypothesis is that vitamin B6 deficiency plays a role in the response because the
symptoms were prevented by supplementing individuals with
the vitamin. Since glutamate can be converted to acetylcholine
by the tricarboxylic acid cycle, it has also been proposed that
the effects are due to an increase in acetylcholine levels. It has
been noted that after MSG ingestion, there is a decrease in the
levels of cholinesterase (the enzyme that breaks down acetylcholine).
Due to inadequate investigations, it is not currently
known if any or all of these mechanisms are responsible for
CRS. The neurotoxicity of MSG has only been demonstrated in
rodent species and rabbits after exposure to very large doses.
The neurotoxic effect has been attributed to excitotoxicity.
Regulatory Status
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.
