USE OF GLUTAMATE IN FOODS AND REGULATIONS

IV. USE OF GLUTAMATE IN FOODS AND REGULATIONS

A. Food Applications

1. Glutamate The major use of MSG in cooking around the world is as a flavor enhancer in soups and

broths, sauces and gravies, and flavorings and spice blends. MSG is also included in a wide variety of canned and frozen meats, poultry, vegetables, and combination dishes. Results of taste panel studies indicate that a level of 0.1–0.8% by weight in food gives the best enhancement of the food’s natural flavor. In home or restaurant cooking, this amounts to about 1–2 teaspoonfuls per kilogram of meat or per 8–12 servings of vegebles, casseroles, soups, etc.

There appears to be some variability from one person to another as to the preferred optimum level of use. Some recipes call for adding MSG during food preparation and then again at the time of serving to ‘‘season to taste.’’ Because MSG is readily soluble in water, recipes often call for dissolving it in the aqueous ingredients of products such

Figure 12 Typical hedonic patterns for four taste substances, showing the self-limiting effect of the amount of MSG (and also NaCl and tartaric acid) to be added to foods. No self-limiting effect is seen with sucrose.

2. 5 ′-Nucleotides Generally, the nucleotides are useful in enhancing the flavor of many products containing

soups, certain canned meats, fish, vegetables, and vegetable juice ( Table 9 ). In animal tissues, IMP is produced from ATP, and thus the IMP content of fresh raw meats is usually rather high. However, the IMP content of processed meat products is usually rather low, because raw meats contain phosphomonoesterase, and the IMP that is naturally present in meat is easily lost in processing steps such as thawing, washing, and salting. The 5 ′-nucleotides added together with glutamate after these steps can be preserved without loss and improve the flavor of the meat products effectively if the phos- phomonoesterase is inactivated by heating the products before or immediately after addi- tion of the 5 ′-nucleotides.

As mentioned previously, the presence of nucleotides enhances the activity of gluta- mate. Both IMP and GMP can greatly reduce the glutamate requirements of many foods. Currently, MSG, IMP, mixtures of IMP and GMP, and mixtures of MSG, IMP, and GMP are commercially available. In most soups, 4.5–7 kg of a 95% MSG/2.5% IMP/2.5% GMP mixture can replace 45 kg of MSG without appreciably changing the flavor of the products (Titus, 1964). In this application, the nucleotide concentration is reduced to the

Table 9 Processed Foods to Which Flavor Enhancers Are Added and Their Usage Levels

Usage levels

5 ′-Nucleotides (50:50

MSG

IMP and GMP)

Canned soups

Canned asparagus

Canned crab

Canned fish

Canned poultry, sausage,

ham Dressings

Soy sauce

Vegetable juice

Processed cheese

Dehydrated soups

Soup powder for instant

noodles Sauces

Source : Maga (1983).

glutamate and the nucleotide is strong enough to give the impression of a much higher concentration of glutamate than is actually present. The amount of this mixture required to give the same flavor effect as 45 kg of MSG varies from product to product but is usually about 7 kg. In one bouillon, only 2.5 kg of the mixture was reported to replace effectively 45 kg of MSG.

Recent developments in processed foods have given rise to many flavoring materials such as hydrolyzed vegetable proteins, hydrolyzed animal proteins, yeast extracts, meat extracts, and vegetable extracts. Hydrolyzed vegetable or animal proteins contain generous amounts of glutamate (approximately 10 g MSG/100 g); meat extracts contain some amount of IMP (approximately 1 g/100 g). GMP-rich yeast extract itself is also available in the market.

Although the nucleotides and glutamate naturally contained in these materials ac- complish the synergism, the additional glutamate and nucleotides enhance the quality of processed foods and result in considerable cost savings.

B. Regulations

The use of monosodium glutamate in foods, like that of hundreds of other flavors, spices, and food additives, is subject to a variety of standards and regulations on a worldwide basis. In 1987, the Joint Expert Committee on Food Additives (JECFA) of the Food and

(FAO/WHO) reviewed and endorsed the safety of glutamate, allocating an acceptable daily intake (ADI) for MSG as ‘‘not specified.’’

The previous numerical ADI has been removed; the implied exclusion of use by humans under the age of 12 weeks has also been deleted. This is JECFA’s most favorable classification for food additives.

JECFA considered the issue of MSG hypersensitivity and concluded that ‘‘studies have failed to demonstrate that MSG is the causal agent in provoking the full range of symptoms of Chinese Restaurant Syndrome. Properly conducted double-blind studies among individuals who claimed to suffer from the syndrome did not confirm MSG as the causal agent’’ (JECFA 1987,1988).

Along with JECFA specifications, various national bodies have also established stan- dards of purity for glutamates. For example, monographs of identity for purity are listed in the U.S. Food Chemicals Codex and the Japanese Standard of Food Additives. In the United States, MSG is included in the GRAS (generally recognized as safe) list of food ingredients by the U.S. Food and Drug Administration, along with salt, pepper, sugar, and vinegar. The Scientific Committee for Foods of the European Community evaluated MSG and gave number E621 as a safe food additive (EL/SCF, 1991). The regulation was published as a Council Directive in 1995 (European Parliament, 1995). In Japan, MSG is a permitted food additive with no limitation.

For calcium and disodium salts of guanylic and inosinic acid, the committee stated ‘‘ADI not specified.’’ This means that, on the basis of the available data—toxicological, biochemical, and so forth—an ADI with a numerical limitation is not deemed necessary (JECFA 1974,1975,1993). These salts are listed as food additives permitted for direct addition food for human consumption.