Products
Glutamate is present in many foods, “convenience foods,” spices, sauces, and broths as a food additive (e.g., E 621). It can be obtained chemically-synthetically, hydrolytically or by fermentation. “Hidden” glutamate, some of which is undeclared, can be found in yeast extract and hydrolyzed vegetable protein, for example.
Structure and properties
Glutamate is usually referred to as monosodium glutamate (C5H8NNaO4, Mr = 169.1 g/mol), a white, odorless crystalline powder that is soluble in water. It is the sodium salt of the amino acid L-glutamic acid. Other glutamates, such as monopotassium glutamate (E 622) or calcium diglutamate (E 623), are also permitted as additives.
Effects
Glutamate has flavor-enhancing properties. Its taste is referred to as “umami” (savory), as a fifth flavor in addition to sweet, salty, sour, and bitter. Glutamate is a natural substance found in numerous proteins in food. High concentrations are found, for example, in tomatoes, meat, fish, mushrooms, kelp, and aged products such as Parmesan cheese, other cheeses, and soy sauce. Glutamate plays an important role in the central nervous system as an excitatory neurotransmitter. The amino acid is also used by the body as a source of energy in the intestines and for biosynthesis of other substances.
Indications for use
Glutamate is used as a flavor enhancer and flavor improver, for example in soup, fish and meat dishes.
Dosage
Ready-to-eat meals typically contain between 0.1% to 0.8% (m/m) glutamate. Approximately 10 g of glutamate is ingested daily with food. As a food additive, up to about 1 g is consumed daily in Europe. These numbers naturally vary greatly from person to person and are higher in Asia.
Adverse effects
Glutamate is generally considered safe and harmless. No adverse effects are expected at normal doses. Whether glutamate intolerance, known as Chinese restaurant syndrome, actually exists is controversial. It is said to manifest itself in sensitive individuals or at unusually high doses in symptoms such as headache, dizziness, a feeling of warmth, chest pain, numbness, a rapid heartbeat, nausea and allergic symptoms.
