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.Monosodium glutamate is found naturally in tomatoes, cheese and other foods.
Pure MSG is reported not to have a pleasant taste until it is combined with a savory aroma.The basic sensory function of MSG is attributed to its ability to enhance savory taste-active compounds when added in the proper concentration. 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.
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. Although other salts of glutamate have been used in low-salt soups, they are less palatable than MSG.