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  MSGBackgroundThe history of MSG and its function as a flavor enhancer is long and interesting. Hundreds of years ago, oriental cooks used dried seaweed called sea tangle to make stock. Dishes prepared with this stock had a rich and full flavor. Much later, a Japanese professor discovered that it was the glutamate in the seaweed that was responsible for the flavor enhancement. As a result, the Japanese began to produce glutamate as an additive, and eventually it was manufactured in North America.1,2 In 1987, the American MSG production total was reported to be 18.6 million pounds.2 MSG was originally produced from seaweed, wheat gluten or corn protein, but today MSG is made commercially through natural fermentation of mainly molasses from sugar cane or sugar beets, or through natural fermentation of corn starch or corn sugar.1,3 Monosodium glutamate (MSG) is one of the glutamate salts of glutamic acid (or L-glutamic acid), an amino acid.3 Glutamic acid is naturally present in most foods in either the free form or bound to peptides and proteins.5 It is a major constituent of food proteins (in some foods comprising 20% of the total amino acid content), such as in meat, fish, milk and some vegetables. In its free form glutamic acid is present in mushrooms, tomatoes, soy sauce and other fermented soy products. The following is a list of food products which contain natural MSG, and the amount of the substance present in each (mg per 100g of food): • Kelp – 2240mg Regardless of dietary source (protein, protein hydrolysates or salts of free glutamic acid, including MSG), all glutamate molecules that are absorbed are structurally identical and are metabolized in the same way. Once glutamate is ingested, our bodies make no distinction among the origins.7 MSG is commercially available as white or almost-white crystals or powder.3 It does not have a distinct taste of its own, but acts as a flavor enhancer in other foods. Its taste is different from the four basic tastes (sweet, sour, salty, bitter) and has been named "umami" by the Japanese.3 Umami describes the savoriness, deliciousness or succulence of a food and has been proposed as a fifth taste sensation.7 Protein-bound glutamic acid, which occurs in virtually all proteins, has no umami effect; only the free form has this property.7 The average daily intake of MSG in adults is estimated to be 0.3-1g in industrialized countries, but can be higher occasionally, depending on the MSG content of individual food items and an individual's taste preferences. As much as 6g of MSG may be ingested in a highly seasoned oriental meal, and a single bowl of wonton soup may contain 2.5g of MSG.4,8,9 USES: MSG is used for developing and enhancing the flavor of, predominantly, savoury products,3 but it is also known to enhance the perception of sweetness and saltiness, and to diminish that of sourness and bitterness.5 MSG is commonly used to enhance the natural flavors of meats, poultry, seafood, soups and stews, but has no flavor-improving effect on some foods such as confectionery and other desserts, dairy products, soft drinks, and fruit drinks. It is used as a flavor enhancer (stimulating taste buds or increasing saliva production) and is often found in Chinese, Japanese and other Southeastern Asian foods. Foods that frequently contain MSG include the following: canned, cured and smoked meats and sausages, commercially prepared dinners, salads and other side dishes, canned soups, dry soup mixes, gravy and seasoning mixes, freeze-dried foods, frozen foods, diet foods, potato chips, crackers and other savory snacks, cookies, salad dressings and mayonnaise, croutons, bottled and canned sauces, and spices and seasonings.7 Besides MSG, other salts of free glutamate have a taste-enhancing effect: examples are monopotassium glutamate and monoammonium glutamate.8 The major reason for using one of these salts will be to produce a “low sodium” or “sodium free” product. However, these salts are almost twenty times more expensive than MSG and are therefore seldom used in the food industry.
ProblemsAdverse reactions (by Karen du Plessis, registered dietitian):
As indicated above, there is an ongoing debate as to whether MSG does in fact cause any of the alleged adverse reactions, as described below.4 There is, in any case, little evidence that MSG causes adverse effects at normal levels of consumption. Adverse reactions to MSG are due to an intolerance; MSG is therefore not regarded as an allergen. Intolerances are related to a dose-response, meaning that an individual may not react to a low dose but is more likely to react above a certain threshold level. The following are the main symptoms and conditions that have been associated with the consumption of MSG: 1. Chinese Restaurant Syndrome: This name was given to a range of symptoms that have occurred in persons after the ingestion of MSG-rich food, typically at Chinese restaurants. Symptoms experienced usually include one or more of the following: headache/migraine, facial flushing, numbness and pain in the back of the neck, feeling of pressure or pain in the face, feeling of pressure in the upper chest muscles, pins and needles in upper limbs, blurred vision, dizziness, problems with balance, sweating, nausea and vomiting, diarrhoea, changes in mood, abdominal pain and cramps, weakness, thirst, heart palpitations, chills and shaking.4,10 The symptoms usually occur within 15-30 minutes of eating a meal high in MSG and continue for about 2 hours.4,10 There is evidence that reactions occur only after ingestion of MSG on an empty stomach, as in a soup at the beginning of a meal. However, many studies have failed to show a relationship between this syndrome and MSG intake.8 2. Neurotoxicity: MSG can be neurotoxic at high doses in several animal species, but this has not been proven for humans. The dose of MSG ingested to induce this effect in animals is many times higher (10 to 40 times) than doses occurring in humans under normal conditions of MSG use, and far exceeds maximum palatable doses.5,8,11,12 3. Asthma: Some studies have suggested that MSG induces or exacerbates asthma (with especially bad effects in patients with severe, poorly controlled asthma), but others could not confirm this.4,8,9,10,11,13,14,15 4. Skin manifestations: There have been some reports that MSG induces or exacerbates urticaria, angioedema and atopic dermatitis, but this could not be proven beyond doubt.8,16,17,18 5. Migraine/headache has been associated with MSG ingestion, but there has also been a great deal of criticism of these studies.8,19,20,21 The discrepancies on whether MSG causes the above reactions are mostly because of the different methods used in the various studies. These studies can therefore not be compared with each other to supply a conclusion. For further details read more in Allergy Advisor Educational Review: Food Problems: It has the greatest flavor affect in low-acid foods such as vegetable and meat products. It has no flavor enhancing effect on high-acid foods such as fruits; neither does it have an effect on milk products or sweet dough, and it will not improve the flavor of poor-quality food.1,7 MSG contains 70% less sodium than sodium chloride (12% vs 39%). For an equal sensation of saltiness, the sodium provided by sodium chloride can be reduced and compensated for by much lower amounts of MSG. By adding MSG appropriately, sodium chloride content can be reduced by 30-40% while maintaining the same perception of saltiness.1,7 Inosine monophosphate (IMP) and MSG are sometimes mixed together, and this mixture will taste 20 times stronger than the same total amount of either one alone. The addition of one of these substances to a food product that naturally contains any amount of the other will have a huge effect on the flavor.6 Food companies can differentiate their products to target a niche market, those consumers who want to avoid or limit their MSG intake. Some companies are already doing this by not adding MSG to their products.
Labelling IssuesIn 1958, the United States Food and Drug Administration (FDA) classified L-glutamic acid and hydrolyzed protein products containing L-glutamic acid (including monosodium glutamate and hydrolyzed vegetable proteins) as generally recognized as safe (GRAS). This status was reaffirmed when the FDA Hypersensitivity Committee in 1986 and the FDA Health Hazards Evaluation Board in 1990 concluded that dietary intake of glutamates does not present a hazard to human health and requires no additional regulatory action. Glutamates were declared safe at current consumption levels for the general population, including children and pregnant and lactating women.4 The Joint FAO/WHO Expert Committee on Food Additives (JECFA) allocated an "acceptable daily intake (ADI) not specified" to glutamic acid and its salts in 1988, which indicates that there were no toxicological concerns associated with their use as food additives in accordance with good manufacturing practice (GMP). The Scientific Committee for Food (SCF) of the European Commission made a similar evaluation in 1991, placing MSG in the safest category for food additives.11,12 MSG is permitted worldwide, although in some countries and for some types of foods, maximum concentration limits apply. Other salts of glutamic acids that are occasionally used are potassium, calcium and ammonium glutamic acids. These salts are not permitted worldwide. Codex Alimentarius as well as most countries' legislation requires that the presence of MSG be indicated on the label of any product.
Food AlertsThe concern around farm-raised salmon, as opposed to wild salmon, is ongoing. Alarmed media reports started with a study being published that found that farm-raised salmon contain considerably more toxic chemicals and higher levels of cancer-causing pollutants, including dioxins, than salmon caught in the wild and may therefore pose health risks.22,23 Contaminants in farmed salmon also may affect neuro-development in children.23 A recent study published in the journal Science suggested the pollutants came from PCBs or polychlorinated biphenyls in the fish oil and meal fed to farm-raised salmon. The Northeast region of the U.S. Fish and Wildlife Service is testing farm-raised salmon and other fish for dioxin and other pollutants. There is a fear that contamination could occur through commonly used feeds. They recommend that farmers changes their fish feed and urged consumers to buy wild salmon. It is uncertain whether fish will be tested in other regions.22
TrendsFoods for allergy and intolerance sufferers represent a niche market in the food industry, and one that is growing at a rapid rate. These foods were in the past manufactured mainly by specialist companies and sold in health food stores, but this is changing. More and more companies are developing and selling food products suitable for one or more type of allergy or intolerance, and these products are available from local retailers. As the prevalence and awareness of food intolerance and food allergy appear to be increasing, there should be many possibilities for the development of food products suitable for food-intolerant or food-allergic consumers. Many considerations are necessary for the manufacture of an “allergen-free” product. The manufacturer must be able to ensure that the food product is in fact allergen-free; otherwise, ingestion could lead to a potentially fatal allergic reaction. There must be absolutely no possibility of allergen cross-contamination during receipt of raw materials, processing or distribution. Concerning an allergen-free claim, such as “Gluten-free,” the labelling regulations of many countries require manufacturers to test the product to ensure that it is truly allergen-free. Products can or must also be tested if there is any possibility of allergen cross-contamination. The most common group of major food allergens are, milk; egg; peanut; tree nuts; soya; fish; crustacea and wheat. However, this may vary greatly from country to country, such as in Israel where sesame is included as one of their major allergens. The development of allergen-free products is not applicable only to food products. There are more and more cosmetic products being designed to accommodate ailments such as asthma, eczema and dermatitis. People with these conditions also represent a growing demand for suitable consumer offerings.
New Products
Journal ArticlesNovel method for the determination of added annatto colour in extruded corn snack products ”There is considerable interest in determining the added levels of the natural dye annatto in foods like snack products, particularly because they are mostly consumed by young people. The objective was to use response surface methodology to develop a new method to analyse annatto in extruded snacks. A pre-treatment of the samples was necessary, digesting the ground sample with alpha-amylase at room temperature. The pigment was extracted by shaking with ethyl acetate at room temperature; eight extractions being necessary for completion extract the pigment. Lipids were removed by alkaline saponification. Under these conditions, 100% of the bixin was converted into norbixin, which was then quantified by high-performance liquid chromatography. The method had a mean recovery of 97% and a coefficient of variation for duplicate analysis of 1%. Using this method, of the 13 commercial samples analysed, a parmesan cheese-flavored snack product showed the highest level of dye expressed as norbixin (15.5 mg kg(-1)), whilst other brands of onion-flavored snack products had the lowest levels (0.7 and 0.4 mg kg(-1), respectively).” Novel method for the determination of added annatto colour in extruded corn snack products. Chemical interactions between additives in foodstuffs: a review Chemical interactions between additives in foodstuffs: a review. Wheat Allergy Food allergy affects 6-8% of infants and wheat allergy is one of the common food allergies among children. For this study children with suspected wheat allergy were evaluated for wheat allergy. Among patients with suspected wheat allergy, 24 patients with definite wheat allergy were identified. Anaphylaxis was a dominant clinical feature, accounting for 54.1% of acute symptoms. Chronic allergy symptoms like asthma and eczema were noted in 50% of the patients. The study concludes that anaphylaxis had occurred in a remarkable number of patients repeatedly, which demonstrates the severity of the reactions, poor knowledge of the disease and probable existence of more patients with mild reactions. The national survey of immediate type of food allergy. [Japanese] Editorial comment: This study highlights the importance of preventing allergen cross-contamination prior to, during and after processing. Undiagnosed coeliac disease at age seven: population based prospective birth cohort study Coeliac disease is uncommon in childhood and diagnosed in less than 1 in 2500 children in the United Kingdom. It is, however, common in adults. At age 7, 1% of children are likely to have subclinical coeliac disease, though less than 0.1% is reported to be on a gluten-free diet. The prevalence of coeliac disease in these children is therefore comparable to that in UK adults. Undiagnosed coeliac disease at age seven: population based prospective birth cohort study. Editorial comment: It is important to note that previous studies under estimated the prevalence of coeliac disease or gluten-sensitivity. This should be a consideration when developing new products.
Compiled by Maritza van DykFACTS REFERENCES |
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