Food Additives

views updated Jun 27 2018

Food Additives







The United States Food and Drug Administration (FDA) defines food additives 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.

Types of ingredientsWhat they doExamples of usesNames found on product labels
PreservativesPrevent food spoilage from bacteria, molds, fungi, or yeast (antimicrobials); slow or prevent changes in color, flavor, or textur and delay rancidity (antioxidants); maintain freshnessFruit sauces and jellies, beverages, baked goods, cured meats, oils and margarines, cereals, dressings, snack foods, fruits and vegetablesAscorbic acid, citric acid, sodium benzoate, calcium propionate, sodium erythorbate, sodium nitrite,calcium sorbate, potassium sorbate, BHA, BHT, EDTA, tocopherols (Vitamin E)
SweetenersAdd sweetness with or without the extra caloriesBeverages, baked goods, confections, table-top sugar, substitutes, many processed foodsSucrose (sugar), glucose, fructose, sorbitol, mannitol, corn syrup, high fructose corn syrup, saccharin, aspartame, sucralose, acesulfame potassium (acesulfame-K), neotame
Color AdditivesOffset color loss due to exposure to light, air, temperature extremes, moisture and storage conditions;correct natural variations in color;enhance colors that occur naturally;provide color to colorless and “fun”foodsMany processed foods (candies, snack foods margarine, cheese, soft drinks, jams/jellies, gelatins, pudding and pie fillings)FD&C Blue Nos. 1 and 2, FD&C Green No. 3, FD&C Red Nos. 3 and 40, FD&C Yellow Nos. 5 and 6, Orange B, Citrus Red No. 2, annatto extract, beta-carotene, grape skin extract, cochineal extract or carmine, paprika oleoresin, caramel color, fruit and vegetable juices, saffron (Note: Exempt color additives are not required to be declared by name on labels but may be declared simply as colorings or color added)
Flavors and SpicesAdd specific flavors (natural and synthetic)Pudding and pie fillings, gelatin dessert mixes, cake mixes, salad dressings, candies, soft drinks, ice cream, BBQ sauceNatural flavoring, artificial flavor, and spices
Flavor EnhancersEnhance flavors already present in foods (without providing their own separate flavor)Many processed foodsMonosodium glutamate (MSG), hydrolyzed soy protein, autolyzed yeast extract, disodium guanylate or inosinate
Fat Replacers (and components of formulations used to replace fats)Provide expected texture and a creamy “mouth-feel” in reduced-fat foodsBaked goods, dressings, frozen desserts, confections, cake and dessert mixes, dairy productsOlestra, cellulose gel, carrageenan, polydextrose, modified food starch, microparticulated egg white protein, guar gum, xanthan gum, whey protein concentrate

source: Center for Food Safety and Applied Nutrition, Food and Drug Administration, U.S. Department of Health and Human Services.

(Illustration by GGS Information Services/Thomson Gale.)


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 hydroxya-nisole (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 wholesome-ness, provide leavening, control pH, enhance flavor, or provide color. Food additives may be classified as:.

  • Antimicrobial agents, which prevent spoilage of food by mold or microorganisms. These include not only vinegar and salt, but also compounds such as calcium

    Food additives

    Types of ingredientsWhat they doExamples of usesNames found on product labels
    NutrientsReplace vitamins and minerals lost in processing (enrichment), add nutrients that may be lacking in the diet (fortification)Flour, breads, cereals, rice, macaroni, margarine, salt, milk, fruit beverages, energy bars, instant breakfast drinksThiamine hydrochloride, riboflavin (Vitamin B2), niacin, niacinamide, folate or folic acid, beta carotene, potassium iodide, iron or ferrous sulfate, alpha tocopherols,ascorbic acid, Vitamin D, amino acids (L-tryptophan, L-lysine, L-leucine, L-methionine)
    EmulsifiersAllow smooth mixing of ingredients, prevent separation. Keep emulsified products stable, reduce stickiness, control crystallization, keep ingredients dispersed, and help products dissolve more easilySalad dressings, peanut butter, chocolate, margarine, frozen dessertsSoy lecithin, mono- and diglycerides, egg yolks, polysorbates, sorbitan monostearate
    Stabilizers and thickeners, binders, texturizersProduce uniform texture, improve “mouth-feel”Frozen desserts, dairy products, cakes, pudding and gelatin mixes, dressings, jams and jellies, saucesGelatin, pectin, guar gum, carrageenan, xanthan gum, whey
    pH Control agents and acidulantsControl acidity and alkalinity, prevent spoilageBeverages, frozen desserts, chocolate, low-acid canned foods, baking powderLactic acid, citric acid, ammonium hydroxide, sodium carbonate
    Leavening agentsPromote rising of baked goodsBreads and other baked goodsBaking soda, monocalcium phosphate, calcium carbonate
    Anti-caking agentsKeep powdered foods free-flowing, prevent moisture absorptionSalt, baking powder, confectioner’s sugarCalcium silicate, iron ammonium citrate, silicon dioxide
    HumectantsRetain moistureShredded coconut, marshmallows, soft candies, confectionsGlycerin, sorbitol
    Yeast nutrientsPromote growth of yeastBreads and other baked goodsCalcium sulfate, ammonium phosphate
    Dough strengtheners and conditionersProduce more stable doughBreads and other baked goodsAmmonium sulfate, azodicarbonamide, L-cysteine
    Firming agentsMaintain crispness and firmnessProcessed fruits and vegetablesCalcium chloride, calcium lactate
    Enzyme preparationsModify proteins, polysaccharides and fatsCheese, dairy products, meat Enzymes, lactase, papain, rennet, chymosin
    GasesServe as propellant, aerate, or create carbonationOil cooking spray, whipped cream, carbonated beveragesCarbon dioxide, nitrous oxide

    source: Center for Food Safety and Applied Nutrition, Food and Drug Administration, U.S. Department of Health and Human Services.

    (Illustration by GGS Information Services/Thomson Gale.)
    propionate and sorbic acid, which are used in products such as baked goods, salad dressings, cheeses, margarines, and pickled foods
  • 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
  • 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)
  • Aritificial 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 ben-zaldehyde 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
  • Bleaching agents, such as peroxides, are used to whiten foods such as wheat flour and cheese
  • 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
  • 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
  • Thickening and stabilizing agents, which function to alter the texture of a food. Examples include the emul-sifier 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 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 amine 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.


Bacteria— Single-celled organisms without nuclei, some of which are infectious.

Bactericidal— A state that prevents growth of bacteria.

Bateriostatic— A substance that kills bacteria.

Carcinogen— A cancer-causing substance.

Enrichment— The addition of vitamins and minerals to improve the nutritional content of a food.

Fermentation— A reaction performed by yeast or bacteria to make alcohol.

Fortification— The addition of vitamins and minerals to improve the nutritional content of a food.

Leavening— Yeast or other agents used for rising bread.

Microorganism— Bacteria and protists; single-celled organisms.

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.



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

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

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

M. Elizabeth Kunkel

Barbara H. D. Luccia.

Food Additives

views updated May 29 2018

Food additives

Food additives are substances added to food as flavorants, nutrients, preservatives, emulsifiers, or colorants. In addition, foods may contain residues of chemicals used during the production of plant or animal crops, including pesticides, antibiotics, and growth hormones. The use of most food additives is clearly beneficial because it results in improved public health and prevention of spoilage, which enhances the food supply. Nevertheless, there is controversy about the use of many common additives and over the presence of contaminants in food. This is partly because some people are hypersensitive and suffer allergic reactions if they are exposed to certain of these chemicals. In addition, some people believe that low levels of chronic toxicity and diseases may be caused in the larger population by exposure to some of these substances. Although there is no compelling scientific evidence that this is indeed the case, the possibility of chronic damage caused by food additives and chemical residues is an important social and scientific issue.

The use of food additives in the United States is closely regulated by the government agencies responsible for health, consumer safety, and agriculture. This is also the case of other developed countries in Europe, Canada, and elsewhere. Chemicals cannot be used as additives in those countries unless regulators are convinced that they have been demonstrated to be toxicologically safe, with a wide margin of security. In addition, chemicals added to commercially prepared foods must be listed on the packaging so that consumers can know what is present in the foodstuffs that they choose to eat. Because of the intrinsic nature of low-level, toxicological risks, especially those associated with diseases that may take a long time to develop, scientists are never able to demonstrate that trace exposures to any chemical are absolutely safethere is always a level of risk, however small.

Name Description Example products
AspartameAn artificial sweetener associated with rashes, headaches, dizziness, depression, etc.Diet sodas, sugar substitutes, etc.
Brominated vegetable oil (BVO)Used as an emulsifier and clouding agent. Its main ingredient, bromate, is a poison.Sodas, etc.
Butylated hydroxyanisole (BHA)/butylated hydroxytoluene (BHT)Prevents rancidity in foods and is added to food packagings. It slows the transfer of nerve impulses and affects sleep, aggressiveness, and weight in test animals.Cereal and cheese packaging
Citrus red dye #2Used to color oranges, it is a probable carcinogen. The FDA has recommended it be banned.Oranges
Monosodium gltamate (MSG)A flavor enhancer that can cause headaches, heart palpitations, and nausea.Fast food, processed and packaged food
NitritesUsed as preservatives, nitrites form cancer-causing compounds in the gastrointestinal tract and have been associated with cancer and birth defects.Cured meats and wine
SaccharinAn artificial sweetener that may be carcinogenic.Diet sodas and sugar substitutes
SulfitesUsed as a food preservative, sulfites have been linked to at least four deaths reported to the FDA in the United States.Dried fruits, shrimp, and frozen potatoes
Tertiary butyhydroquinone (TBHQ)It is extremely toxic in low doses and has been linked to childhood behavioral problems.Candy bars, baking sprays, and fast foods
Yellow dye #6Increases the number of kidney and adrenal gland tumors in lab rats. It has been banned in Norway and Sweden.Candy and sodas

Because some people object to these potential, low-level, often involuntary risks, a certain degree of controversy will always be associated with the use of food additives. This is also true of the closely related topic of residues of pesticides, antibiotics, and growth hormones in foods.


Certain chemicals are added to foods to enhance their flavor. This is particularly true of commercially processed or prepared foods, such as canned vegetables and frozen foods and meals. One of the most commonly added flavorants is table salt (or sodium chloride), a critical nutrient for humans and other animals. In large amounts, however, sodium chloride can predispose people to developing high blood pressure, a factor that is important in strokes and other circulatory and heart diseases.

Table sugar (or sucrose), manufactured from sugar cane or sugar beets, and fructose, or fruit sugar, are commonly used to sweeten prepared foods. Such foods include sugar candies, chocolate products, artificial drinks, sweetened fruit juices, peanut butter, jams, ketchup, and most commercial breads. Sugars are easily assimilated from foods and are a useful form of metabolic energy. In large amounts, however, sugars can lead to weight gain, tooth decay, and hypoglycemia and diabetes in genetically predisposed people. Artificial sweeteners such as saccharine, aspartame, and sodium cyclamate avoid the nutritional problems associated with eating too much sugar. These nonsugar sweeteners may have their own problems, however, and some people consider them to be a low-level health hazard.

Monosodium glutamate (or MSG) is commonly used as a flavor enhancer, particularly in processed meats, prepared soups, and oriental foods. Some people are relatively sensitive to this chemical, developing headaches and other symptoms that are sometimes referred to as "Chinese food syndrome." Other flavorants used in processed foods include many kinds of spices, herbs, vanilla, mustard, nuts, peanuts, and wine. Some people are extremely allergic to even minute exposures to peanuts or nuts in food and can rapidly develop a condition known as anaphylactic shock, which is life-threatening unless quickly treated with medicine. This is one of the reasons why any foods containing peanuts or nuts as a flavoring ingredient must be clearly labeled as such.

Many flavorants are natural in origin. Increasingly, however, synthetic flavorants are being discovered and used. For example, vanilla used to be extracted from a particular species of tropical orchid and was therefore a rather expensive flavorant. However, a synthetic vanilla flavorant can now be manufactured from wood-pulp lignins, and this has made this pleasant flavor much more readily available than it used to be.


Many foods are fortified with minerals, vitamins, and other micronutrients. One such example is table salt, which has iodine added (as potassium iodide) to help prevent goiter in the general population. Goiter used to be relatively common but is now rare, in part because of the widespread use of iodized salt.

Other foods that are commonly fortified with minerals and vitamins include milk and margarine (with vitamins A and D), flour (with thiamine, riboflavin, niacin, iron), and some commercial breads and breakfast cereals (with various vitamins and minerals, particularly in some commercial cereal preparations). Micronutrient additives in these and other commercial foods are carefully formulated to help contribute to a balanced diet in their consumers. Nevertheless, some people believe that it is somehow un-natural and un-healthy to consume foods that have been adulterated in this manner, and they prefer to eat "natural" foods that do not have any vitamins or minerals added to them.


Preservatives are substances added to foods to prevent spoilage caused by bacteria, fungi , yeasts, insects, or other biological agents. Spoilage can lead to a decrease in the nutritional quality of foods, to the growth of food-poisoning microorganisms such as the botulism bacterium, or to the production of deadly chemicals, such as aflatoxin , that can be produced in stored grains and seeds (such as peanuts) by species of fungi.

Salt has long been used to preserve meat and fish, either added directly to the surface or by immersing the food in a briny solution. Nitrates and nitrites (such as sodium nitrate, or saltpetre) are also used to preserve meats, especially cured foods such as sausages, salamis, and hams. These chemicals are especially useful in inhibiting the growth of Clostridium botulinum, the bacterium that causes deadly botulism. Vinegar and wood smoke are used for similar purposes. Sulfur dioxide , sodium sulfite, and benzoic acid are often used as preservatives in fruit products, such beverages as wine and beer, and in ketchup, pickles, and spice preparations.

Anti-oxidants are chemicals added to certain foods to prevent a deterioration in their quality or flavor, occurring due to the exposure of fats and oils to atmospheric oxygen. Examples of commonly used antioxidants are ascorbic acid (or vitamin C), butylated hydroxyanisole (or BHA), butylated hydroxytoluene (or BHT), gallates, and ethoxyquin.

Stabilizers and emulsifiers

Stabilizers and emulsifiers are added to prepared foods to maintain suspensions of fats or oils in water matrices (or vice versa), or to prevent the caking of ingredients during storage or preparation. One example of an emulsifying additive is glyceryl monostearate, often added to stored starch products to maintain their texture. Alginates are compounds added to commercial ice cream, salad dressing, and other foods to stabilize emulsions of oil- or fat-in-water during storage.


Some prepared foods have colors added to "improve" their aesthetic qualities and thereby to make them more attractive to consumers. This practice is especially common in the preparation of confectionaries such as candies, chocolate bars, ice creams, and similar products, and in fancy cakes and pastries. Similarly, products such as ketchup and strawberry preserves have red dyes added to enhance their color, relishes and tinned peas have green colors added, and dark breads may contain brown colorants. Most margarines have yellow colors added, to make them appear more similar to butter. Artificial drinks and drink-mixes contain food colorants appropriate to their flavor--cherry and raspberry contain red dyes, and so forth.

Various chemicals are used as food colorants, some of them being extracted from plants (for example, yellow and orange carotenes), while many others are synthetic chemicals derived from coal tars and other organic substances. The acute toxicity (i.e., short-term poisoning ) and chronic toxicity (i.e., longer-term damage associated with diseases, cancers, and developmental abnormalities) of these colorants are stringently tested on animals in the laboratory, and the substances must be demonstrated to be safe before they are allowed to be used as food additives. Still, some people object to having these chemicals in their food, and choose to consume products that are not adulterated with colorants.

Residues of pesticides, antibiotics, and growth hormones

Insecticides, fungicides, herbicides, and other pesticides are routinely used in modern, industrial agriculture. Some of these chemicals are persistent, because they do not quickly break down in the environment to simpler substances, and/or they do not readily wash off produce. The chemicals in such cases are called residues, and it is not unusual for them to be present on or in foodstuffs in low concentrations. The permissible residue levels allowed in foodstuffs intended for human consumption are closely regulated by government. However, not all foods can be properly inspected, so it is common for people to be routinely exposed to small concentrations of these chemicals in their diet.

In addition, most animals cultivated in intensive agricultural systems, such as feedlots and factory farms, are routinely treated with antibiotics in their feed. This is done to prevent outbreaks of communicable diseases under densely crowded conditions. Antibiotic use is especially common during the raising of chickens, turkeys, pigs, and cows. Small residues of these chemicals remain in the meat, eggs, milk, or other products of these animals, and are ingested by human consumers. Also, growth hormones are given to beef and dairy cows to increase their productivity. Small residues of these chemicals also occur in products eaten by consumers.

Strictly speaking, residues of pesticides, antibiotics, and growth hormones are not additives because they are not added directly to foodstuffs. Nevertheless, these chemicals are present in foods eaten by people, and many consumers find this to be objectionable. So-called organic foods are cultivated without the use of synthetic pesticides, antibiotics, or growth hormones, and many people prefer to eat these foods instead of the much more abundantly available foodstuffs that are typically sold in commercial outlets. (Note that the term "organic foods" is somewhat of a misnomer, because all foods are organic in nature. The phrase "organic" in this sense is used to refer to foods containing additives and/or residues, etc.)

Irradiation of food

Irradiation is a new technology that can be used to prevent spoilage of foods by sterilizing most or all of the microorganisms and insects that they may contain. This process utilizes gamma radiation, and it is not known to cause any chemical or physical changes in foodstuffs, other than the intended benefit of killing organisms that can cause spoilage. Although this process displaces some of the uses of preservative chemicals as food additives, irradiation itself is somewhat controversial. Even though there is no scientific evidence that food irradiation poses tangible risks to consumers, some people object to the use of this technology and prefer not to consume foodstuffs processed in this manner.

[Bill Freedman Ph.D. ]



British Nutrition Foundation. Why Additives? The Safety of Foods. London: Forbes, 1977.

Freed, D. L. J. Health Hazards of Milk. London: Bailliere Tindall, 1984.

Marcus, A. I. Cancer from Beef: DES, Federal Food Regulation, and Consumer Confidence. Baltimore: Johns Hopkins University Press, 1994.

Miller, M. Danger! Additives at Work: A Report on Food Additives, Their Use and Control. London: London Food Commission, 1985.

Safety and Nutritional Adequacy of Irradiated Food. Geneva, Switzerland: World Health Organization, 1994.


Etherton, T. D. "The Impact Of Biotechnology On Animal Agriculture And The Consumer." Nutrition Today 29, no. 4 (1994): 1218.

food additive

views updated May 21 2018

food additive A substance added to a food during its manufacture or processing in order to improve its keeping qualities, texture, appearance, or stability or to enhance its taste or colour. Additives are usually present in minute quantities; they include colouring materials, sweeteners, preservatives (see food preservation), antioxidants, emulsifiers, and stabilizers. In most countries the additives used must be selected from an approved list of such compounds, which have been tested for safety, and they must be listed on the food labels of individual products.

food additive

views updated May 23 2018

food additive Substance introduced into food to enhance flavour, to act as a preservative, to effect a better external coloration or more appetizing appearance, or to restore or increase nutritional value. Other additives include thickeners, stabilizers and anti-caking agents. The use of food additives is strictly regulated by law and requires prominent labelling. The 208 food additives approved for use in the EU carry an E number.