Monosodium Glutamate (MSG)
What it does
Umami flavour enhancer.
How it's made
Made by bacterial fermentation of starch/sugar.
Monosodium glutamate (MSG) is the sodium salt of glutamic acid and the best-known flavour enhancer, used to intensify the savoury "umami" taste of soups, sauces, stocks, snacks and ready meals. The glutamate it provides is the same as that occurring naturally in many foods.
It is manufactured by fermentation. Bacteria are grown on a carbohydrate feedstock such as molasses, sugar cane or starch hydrolysate, and are cultivated to overproduce glutamic acid, which is secreted into the broth. The glutamic acid is then neutralised with a controlled amount of sodium (usually sodium hydroxide) to form monosodium glutamate.
The MSG is purified, decolourised and crystallised into the familiar white crystals. Because it is made by fermentation and then crystallised, it is a pure, single compound; despite long-standing anecdotes, controlled studies have not shown that normal dietary amounts cause the reactions once attributed to it, though it does contribute sodium.
Possible reactions
\"Chinese restaurant syndrome\" (headache, flushing, sweating) reported by some, though controlled studies are inconsistent.