Monosodium glutamate ( MSG ) - The Third Spice
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HISTORY.

Monosodium glutamate, more commonly referred to as MSG, is a sodium salt (C5H8NNaO4) of the non-essential amino acid glutamic acid. It is used as a flavor enhancer.
Previously it was made by hydrolysis of wheat gluten, which contains about 25% glutamic acid, but since the mid 1960s it is mostly made by submerged bacterial fermentation of carbohydrates.
Also seaweed is rich glutamic acid and seaweed extract has been a valuable flavor enhancer in the past. In 1907 MSG was isolated for the first time.
In its pure form, MSG appears as a white crystalline powder. In water, it rapidly dissociates into sodium and glutamate ions.

Anhydrous:     C5H8NNaO4 169.1 g/mol
Monohydrate: C5H8NNaO4, H2O 187.1 g/mol

SYNONYMS AND SIMILARS.


Monosodium glutamate
L(+)-Monosodium glutamate monohydrate
L(+)-Monosodium glutamate anhydrous
MSG
E621 (European Union E-number)
Third spice (After salt and pepper)
Natural Flavoring (Common product label)
Accent (Trade name)
Aji-no-moto (Trade name)
Vetsin (Trade name)
Hydrolyzed Vegetable Protein (rich in MSG)
Autolyzed Yeast (rich in MSG)
Yeast Extract (rich in MSG)
Soy Sauce (rich in MSG)

PRODUCTION AND CHEMICAL PROPERTIES

MSG exists as stereoisomer's but only the naturally occurring L-glutamate form is used as a flavor enhancer.
Manufactured MSG contains over 99 % of the naturally predominant L-glutamate form. To achieve this an old trick is required. In the manufacturing process a fermentation step is introduced in an otherwise chemical synthesis just like manufacturing L-ascorbic acid. Instead of a racemic mixture of left- and right-handed enantiomers as would be the result of a pure chemical reaction, microorganisms are in favor of the natural occurring L-form.
Bacterial species such as Corynebacterium  glutamicum find use in the fermentation process.
Crystallization of the fermented concentrate facilitates its purification.

UMAMI.

In Japan a century ago a fifth basic taste umami or meaty taste - was discovered in addition to the recognized taste of sweet, salty, sour and bitter. Umami is associated with natural products like ripe tomato, green tea and MSG is a manufactured umami ingredient.
Other umami components are ribonucleotides (RNA). Taste synergism between glutamate and nucleotides exists and when glutamate and 5'-ribonucleotides are mixed together, the intensity of the umami taste is markedly enhanced. The umami taste characteristics have been defined on the first international umami symposium 1985 in Hawaii.

RAW MATERIALS

In Brazil cane sugar and molasses as raw material for the fermentation is an obvious choice. Other fermentation processes are, however, competing for molasses as raw material and most recently the outlet for fermented ethanol bio fuel has become huge. This is one reason for a growing interest in other carbohydrates and starch in particular. Starchy crops are cultivated as economically and feasible as cane and beet. In the tropical region cassava can be grown and harvested round the year a big advantage.

PROCESS

A typical process based on cassava begins in the field, where cassava roots are lifted, trimmed and transported to the factory for immediate processing.

First step on the factory - washing and peeling is carried out continuously on dry and wet rotating screens.

The clean roots are chopped and grated to a fine pulpy mass. The starch is extracted on conical rotating screens by flushing the pulp with the root juice itself leaving the residual wet pulp as a by-product useful as cattle feed or soil improver.

The extracted crude starch suspension crude starch milk is separated from the juice on hydrocyclones. The juice is eventually discarded as a by-product useful as a natural fertilizer or preferably turned into bio gas powering the plant.

The concentrated crude starch milk is refined on multi stage hydrocyclones in concurrent with fresh water leaving the last stage as a pure concentrated starch slurry with 21o Baum.

There is no need to dry the starch. Better is to hydrolyze it right away into glucose syrup starch sugar syrup replacing the traditional molasses as feed for the microbes.

First step in this transformation is liquefaction of the starch by acid or better with alpha-amylase. This step will hydrolyze the starch into shorter chains of polysaccharides with a rater low Dextrose Equivalent (DE) preparing it for the second step.

The liquefaction is followed by a more complete saccharification to a high DE hydrolysate with amyloglucosidase to a mixture of the monosaccharide dextrose and smaller amounts of the disaccharide maltose and lower polysaccharides. This intermediate product will replace the traditional beet and cane sugar in the subsequent fermentation.

In this method bacteria are grown aerobically in a liquid nutrient medium with the starch sugar syrup as the carbohydrate constituent and ammonia as the nitrogen source. The growth media must also contain minerals and growth factors trace elements often obtained from corn steep liquor but the cassava juice may serve as well.

To ensure proper digestion of the carbohydrate, the fermentation is carried out as a batch operated process and to provide the time required the bioreactors are made to hold volumes of up to five hundred cubic meters. The feed is prepared in the fermentation kitchen, UHT-sterilized and transferred aseptic to the pre-sterilized bioreactors.. The bacterial culture is propagated on a small scale and up-scaled a few times before the feed is inoculated. Filtered sterile air is supplied throughout the digestion.

The bacteria selected for this process are forced to overproduce glutamate and to excrete the glutamic acid they synthesize outside of their cell membrane. The glutamic acid accumulates in the fermentation broth  and is separated as an aqueous solution from the broth by microfiltration.

The filtrate is concentrated by evaporation and purified and solidified by crystallization. The crystals are dried and sifted ready for commercialization.

Because the market demands a range of purities from 65% to 99% MSG monohydrate, the finishing step has to be adapted to actual market requirements. Moderate solubility in water facilitates crystallization as the prime purification method for certain qualities.

MARKET

Once associated with foods in Chinese restaurants, MSG is now used worldwide and particularly in processed foods.

A range of MSG-purities from 65% to 99% is available dependent on the actual application.

Manufactured MSG is competing with glutamate brewed products such as soy sauce, steak sauce and Worcestershire sauce.

Although MSG intolerance - the "MSG symptom complex or the Chinese restaurant syndrome - has been reported the FDA concluded that MSG is safe for most people at moderate and customary levels in combination with food. Today it is generally accepted among toxicologists that MSG is a harmless ingredient for most people.

The Ajinomoto Company was formed in 1909 to manufacture and market MSG in Japan and they introduced MSG to the United States in 1947. Ajinomoto is still the market leader with 30-35% of the market for the umami ingredient, monosodium glutamate followed second by Vedan, Taiwan (300,000 MT). A dozen others are important players.

Outside Japan Ajinomoto produces 60,000 MT in Vietnam, 150,000 MT on its two Brazilian subsidiaries.

Next to antibiotics amino acids are the fastest growing fermented commodities.

Umami Manufacturers Association of Japan and European Association for Umami, are examples of associations devoted to this particular flavor. The Umami Information Center (UIC) was established in 1982.

APPLICATIONS

MSG is used commercially as a flavor enhancer in:

Barbecue sauce
Prepared food
Salad dressing
Seasoning mixtures
Snacks
Stock cubes

Typical application of MSG monohydrate actual level to be tailored to taste:

Dehydrated soups 6-8%
Canned meat, 0.1-0.2%
Fish 0.2%
Soups 0.15%
Gravies 0.25%
Sausage 0.3%
Fast foods 0.1%
Ketchup 0.2%
Mayonnaise 0.4%
Soy sauce 0.1%
Shellfish 0.1%