Monosodium Glutamate from Corn: What Is E621 and How MSG Is Made

Gluten is a by-product obtained in the production of corn starch. By gluten here we mean the main water-insoluble impurity of starch milk.

Gluten consists mainly of insoluble proteins together with a portion of starch, makes a good animal feed, and is used in that role. In the 1960s it became clear that corn gluten could yield more valuable products — an effective medicinal agent and a new, superb food seasoning.

What is glutamic acid and why does it matter?

Glutamic acid is one of the 20 amino acids from which all protein substances are built, and its taste properties were first noted more than a century ago. In 1909 the Japanese scientist Dr. Kikunae Ikeda drew attention to the flavour qualities of glutamic acid and its sodium salt.

Glutamic acid has been known for a long time, but it attracted close attention from physiologists, physicians, chemists and technologists only in recent decades. The reason is that glutamic acid plays a very important part in the process of nitrogen metabolism in the human body.

During the digestion of food, protein substances break down into the simplest compounds, one of which is ammonia. Glutamic acid binds ammonia, neutralises its toxic action, and helps remove it from the body. This is why glutamic acid is now used in the treatment of certain nervous and psychiatric disorders.

Dr. Ikeda's discovery concerned taste: even a very small addition of glutamic acid to food — and better still its sodium salt, monosodium glutamate — makes food tastier and creates the illusion of a meaty flavour. This property of glutamic acid became known as the "glutamic effect."

Monosodium glutamate later came to be widely used in many countries as a flavour seasoning for various dishes. There is now a widespread view that monosodium glutamate is harmful to health in large amounts. In the CIS countries it is used to season certain food concentrates, canned goods and cooked sausages.

The first successful experiments in producing monosodium glutamate from corn gluten were carried out in the 1960s at the Leningrad Chemical and Food Combine. Afterwards, the Central Research Institute of the Starch and Syrup Industry worked out in detail the technological scheme for obtaining glutamic acid from corn gluten.

How is glutamic acid obtained from corn gluten?

Glutamic acid is obtained by freeing the gluten of impurities and then hydrolysing it, and the scheme in brief comes down to the following operations. The gluten is freed from carbohydrate impurities (starch and the like), dehydrated, and then hydrolysed by boiling in the presence of hydrochloric acid.

The resulting protein hydrolysate is neutralised with a solution of caustic alkali. When the neutralised hydrolysate is cooled, some of the amino acids produced by the breakdown of the protein precipitate out.

The hydrolysate is then purified with activated carbon and acidified. Under these conditions glutamic acid crystallises out. The pure glutamic acid is separated from the mother liquor, dried at a temperature of 60 °C, and sieved.

To obtain monosodium glutamate, the calculated amount of soda is added to the glutamic acid solution. The yield of glutamic acid is approximately 5% of the weight of the dry, starch-free gluten.