Monosodium Glutamate MSG

Glutamic acid was isolated by Ritthausen (cf. 1.2.2.2). In 1908 Ikeda found that MSG is the beneficial active component of the algae Laminaria japonica, used for a long time in Japan as a flavor improver of soup and similarly prepared food. The consumption of MSG in 1978 was 200,000 tonnes worldwide. 

The taste of MSG cannot be explained by a combination of sweet, salty, sour and bitter tastes. It is, as the fifth quality, of an elementary nature. This assumption, which was made as early as 1908 by a Japanese researcher to explain the special taste called umami, was confirmed by the identification of a taste receptor for MSG. The sixth quality of taste is fatty (cf 3.1). Indeed, MSG is one of the most important taste-bearing substances in meat (cf. 12.9) and cheese ripened 

The taste of MSG is intensified by certain nucleotides (Fig. 8.1). Glutamate promotes sensory perception, particularly of meat-like aroma notes, and is frequently used as an additive in frozen, dehydrated or canned fish and meat products. MSG is added in the concentration range of 0.2-0.8%. The intake of larger amounts of MSG by some hypersensitive persons can trigger a Chinese restaurant syndrome , v hich is characterized by temporary disorders such as drowsiness, headache, stomach ache and stiffening of joints. These disappear after a short time. 

5 -Inosine monophosphate (IMP, disodium salt) and 5 -guanosine monophosphate (GMP, disodium salt) have properties similar to MSG but heightened by a factor of 10-20. Their flavor enhancing ability at 75-500 ppm is good in all food (e. g. soups, sauces, canned meat or tomato juice). However, some other specific effects, besides the MSG effect , have been described for nucleotides. For example, they imprint a sensation of higher viscosity in liquid food. The sensation is often expressed as freshness or naturalness , the expressions body and mouthfeel being more appropriate for soups. 

Synergistic flavor-enhancing effects are experienced with simultaneous use of MSG and IMP or GMP (Fig. 8.1). A mixture of MSG (59 mmol) and GMP (2.75 mmol) can replace 1230 mmol of MSG. 

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A seasoning is anything that enhances in flavor or appearance, or gives reflsh to foods. Spices, condiments, and salt or monosodium glutamate (MSG) are all seasonings (see Amino acids (msg)). 

Defatted peanuts are high in protein, low in moisture, contain only 20% of the naturally occurring fat, and have better stability than whole peanuts. Monosodium glutamate (MSG) has been used as a flavor enhancer for defatted nuts, but the result has not been entirely satisfactory as the addition of MSG produces a meaty rather than nutty flavor. This meaty flavor is more compatible with salted butter and nuts than with candy. 

In the food industries a number of amino acids have been widely used as flavor enhancers and flavor modifiers (see Flavors and spices). For example, monosodium L-glutamate is well-known as a meat flavor-enhancer and an enormous quantity of it is now used in various food appHcations (see Amino acids, L-MONOSODIUM glutamate (MSG)). Protein, hydroly2ed by acid or en2yme to be palatable, has been used for a long time in flavoring agents. 

In the case of hyperphenylalaninaemia, which occurs ia phenylketonuria because of a congenital absence of phenylalanine hydroxylase, the observed phenylalanine inhibition of proteia synthesis may result from competition between T.-phenylalanine and L-methionine for methionyl-/RNA. Patients sufferiag from maple symp urine disease, an inborn lack of branched chain oxo acid decarboxylase, are mentally retarded unless the condition is treated early enough. It is possible that the high level of branched-chain amino acids inhibits uptake of L-tryptophan and L-tyrosiae iato the brain. Brain iajury of mice within ten days after thek bkth was reported as a result of hypodermic kijections of monosodium glutamate (MSG) (0.5—4 g/kg). However, the FDA concluded that MSG is a safe kigredient, because mice are bom with underdeveloped brains regardless of MSG kijections (106). 

Disorders of nervous system mediator release may be caused by aspartame, monosodium glutamate (MSG) ( Chinese restaurant syndrome , Hot-dog headache, or glutamate-induced asthma), and sulphites found in dried fruit, vegetables, pickled vegetables, and fruit juices. 

Food and feed additives do not stand back with regard to the diversity of products. They extend from minerals, mainly calcium, phosphorus, and potassium, to amino acids, vitamins and natural spices. All in all, there are several hundred individual compounds used as feed and food additives. The most expensive product is saffron, made from the stigmas of the saffron crocus flower. The yearly production amounts to about 700,000 kg, and the spice is retailing for about 2500/kg. Amino acids play a big role the largest product is monosodium glutamate (MSG), with a yearly production of 1.5-2 million tons and a price of about 2.30 per kilogram, followed by L-lysine (850,000 tons/ 1.50/kg), D,L-methionine (600,000 tons/ 3/kg), L-threonine (85,000 tons, 3.40/kg), and L-tryptophane (1750 tons/ 24/kg). Major producers of... 

The flavor enhancer monosodium glutamate (MSG) is currently used in virtually every type of savory prepared-food. Unfortunately, MSG has several deleterious side effects on a large proportion of the population. Fortunately, a naturally occurring peptide isolated from a muscle food (beef) can serve not only as a potential replacement for MSG but also as a nutritional adjuvant. The peptide, called BMP or beefy meaty peptide, acts as a flavor enhancer and is found to occur naturally in beef Chapter 6). Research on BMP suggest that it is not only non-allergenic but, by virtue of its protein composition, is a nutritionally sound replacement for MSG. 

Salt is the best known taste enhancer for a variety of foods. Monosodium glutamate (MSG) and nucleotides, such as inosine monophosphate (IMP) and guanosine monophosphate (GMP), are known to enhance flavor and are recognia as the "umami taste" in Oriental cuisine. They have longer aftertastes than the "basic... 

Sodium Ion. The excessive intake of sodium ion coming from other than NaCl should be noticed, though reduced intake of NaCl is now a matter of great concern. Monosodium glutamate (MSG), for instance, is a subject of discussion. Since MSG effectively provides umami taste, it has been very popular as a Japanese seasoning. In the United States, MSG has currently been mark as a cause of "Chinese restaurant syndrome". In addition, beef, liver, blood and their processed foods contains a large amount of sodium ion. Sine sodium ion combines with aspartic acid and glutamic acid residues in protein, study of affinity of acidic amino acids to sodium ion has to be set out first. 

An alternative approach is taken in the production of monosodium glutamate (MSG) which, unlike interferon, is secreted into the fermentation broth. The stages of downstream processing for MSG are shown in Figure 14.3. Again, a variety of unit operations, including centrifugation, crystallization, vaporization, and fixed-bed adsorption, are used in this process. 

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