Additives and Preservatives

Additives are defined by the United States Food and Drug Administration (FDA) as "any substance, the intended use of which results or may reasonably be expected to result, directly or indirectly, in its becoming a component or otherwise affecting the characteristics of any food." In other words, an additive is any substance that is added to food. Direct additives are those that are intentionally added to foods for a specific purpose. Indirect additives are those to which the food is exposed during processing, packaging, or storing. Preservatives are additives that inhibit the growth of bacteria, yeasts, and molds in foods.

Additives and preservatives have been used in foods for centuries. When meats are smoked to preserve them, compounds such as butylated hydroxyanisole (BHA) and butyl gallate are formed and provide both antioxidant and bacteriostatic effects. Salt has also been used as a preservative for centuries. Salt lowers the water activity of meats and other foods and inhibits bacterial growth. Excess water in foods can enhance the growth of bacteria, yeast, and fungi. Pickling, which involves the addition of acids such as vinegar, lowers the pH of foods to levels that retard bacterial growth. Some herbs and spices, such as curry, cinnamon, and chili pepper, also contain antioxidants and may provide bactericidal effects.

Uses of Additives and Preservatives in Foods

Additives and preservatives are used to maintain product consistency and quality, improve or maintain nutritional value, maintain palatability and wholesomeness, provide leavening, control pH, enhance flavor, or provide color. Food additives may be classified as:

1. Antimicrobial agents, which prevent spoilage of food by mold or micro-organisms. These include not only vinegar and salt, but also compounds such as calcium propionate and sorbic acid, which are used in products such as baked goods, salad dressings, cheeses, margarines, and pickled foods.
2. Antioxidants, which prevent rancidity in foods containing fats and damage to foods caused by oxygen. Examples of antioxidants include vitamin C, vitamin E, BHA, BHT (butylated hydroxytolene), and propyl gallate.
3. Artificial colors, which are intended to make food more appealing and to provide certain foods with a color that humans associate with a particular flavor (e.g., red for cherry, green for lime).
4. Artificial flavors and flavor enhancers, the largest class of additives, function to make food taste better, or to give them a specific taste. Examples are salt, sugar, and vanilla, which are used to complement the flavor of certain foods. Synthetic flavoring agents, such as benzaldehyde for cherry or almond flavor, may be used to simulate natural flavors. Flavor enhancers, such as monosodium glutamate (MSG) intensify the flavor of other compounds in a food.
5. Bleaching agents, such as peroxides, are used to whiten foods such as wheat flour and cheese.
6. Chelating agents, which are used to prevent discoloration, flavor changes, and rancidity that might occur during the processing of foods. Examples are citric acid, malic acid, and tartaric acid.
7. Nutrient additives, including vitamins and minerals, are added to foods during enrichment or fortification. For example, milk is fortified with vitamin D, and rice is enriched with thiamin, riboflavin, and niacin.
8. Thickening and stabilizing agents, which function to alter the texture of a food. Examples include the emulsifier lecithin, which, keeps oil and vinegar blended in salad dressings, and carrageen, which is used as a thickener in ice creams and low-calorie jellies.

Regulating Safety of Food Additives and Preservatives

Based on the 1958 Food Additives Amendment to the Federal Food, Drug, and Cosmetic (FD&C) Act of 1938, the FDA must approve the use of all additives. The manufacturer bears the responsibility of proving that the additive is safe for its intended use. The Food Additives Amendment excluded additives and preservatives deemed safe for consumption prior to 1958, such as salt, sugar, spices, vitamins, vinegar, and monosodium glutamate. These substances are considered "generally recognized as safe" (GRAS) and may be used in any food, though the FDA may remove additives from the GRAS list if safety concerns arise. The 1960 Color Additives Amendment to the FD&C Act required the FDA to approve synthetic coloring agents used in The legendary longevity of some packaged foods such as Twinkies, is attributable in part to food additives that stabilize ingredients and prevent spoilage. Additives also enhance the nutrition, flavor, and consistency of foods. [Photograph by Orlin Wagner. AP/Wide World Photos. Reproduced by permission.]
foods, drugs, cosmetics, and certain medical devices. The Delaney Clause, which was included in both the Food Additives Amendment and Color Additives Amendment, prohibited approval of any additive that had been found to cause cancer in humans or animals. However, in 1996 the Delaney Clause was modified, and the commissioner of the FDA was charged with assessing the risk from consumption of additives that may cause cancer and making a determination as to the use of that additive.

The FDA continually monitors the safety of all food additives as new scientific evidence becomes available. For example, use of erythrosine (FD&C Red No. 3) in cosmetics and externally applied drugs was banned in 1990 after it was implicated in the development of thyroid tumors in male rats. However, the cancer risk associated with FD&C Red No. 3 is about 1 in 100,000 over a seventy-year lifetime, and its use in some foods, such as candies and maraschino cherries, is still allowed. Tartrazine (FD&C Yellow No. 5) has been found to cause dermatological reactions ranging from itching to hives in a small population subgroup. Given the mild nature of the reaction, however, it still may be used in foods.

Nitrites are also a controversial additive. When used in combination with salt, nitrites serve as antimicrobials and add flavor and color to meats. However, nitrite salts can react with certain amines in food to produce nitrosamines, many of which are known carcinogens. Food manufacturers must show that nitrosamines will not form in harmful amounts, or will be prevented from forming, in their products. The flavoring enhancer MSG is another controversial food additive. MSG is made commercially from a natural fermentation process using starch and sugar. Despite anecdotal reports of MSG triggering headaches or exacerbating asthma, the Joint Expert Committee on Food Additives of the United Nations Food and Agriculture Organization, the World Health Organization, the European Community's Scientific Committee for Food, the American Medical Association, and the National Academy of Sciences have all affirmed the safety of MSG at normal consumption levels.

In the United States, food additives and preservatives play an important role in ensuring that the food supply remains the safest and most abundant in the world. A major task of the FDA is to regulate the use and approval of thousands of approved food additives, and to evaluate their safety. Despite consumer concern about use of food additives and preservatives, there is very little scientific evidence that they are harmful at the levels at which they are used.

In Europe, food additives and preservatives are evaluated by the European Commission's Scientific Committee on Food. Regulations in European Union countries are similar to those in the United States. The Food and Agricultural Organization (FAO) of the United Nations and the World Health Organization (WHO) Expert Committee on Food Additives work together to evaluate the safety of food additives, as well as contaminants, naturally occurring toxicants, and residues of veterinary drugs in foods. Acceptable Daily Intakes (ADIs) are established on the basis of toxicology and other information.

M. Elizabeth Kunkel Barbara H. D. Luccia

Bibliography

Branen, A. Larry (2002). Food Additives, 2nd edition. New York: Marcel Dekker.

Clydesdale, Fergus M. (1997). Food Additives: Toxicology, Regulation, and Properties. Boca Raton, FL: CRC Press.

Potter, Norman N., and Hotchkiss, Joseph H. (1995) Food Science, 5th edition. New York: Chapman & Hall.