In food, any natural or artificial chemical added to prolong the shelf life of processed foods (salt or nitrates), alter the colour, texture, or flavour of food, or improve its food value (vitamins or minerals). Many chemical additives are used and they are subject to regulation, since individuals may be affected by constant exposure even to traces of certain additives and may suffer side effects ranging from headaches and hyperactivity to cancer. However, it can be difficult to know how to test the safety of such substances; many natural foods contain toxic substances which could not pass the tests applied today to new products.
Food companies in many countries are now required by law to list additives used in their products. Within the European Union, approved additives are given an official E number.
Flavours are intended to increase the appeal of the food and are used to alter or intensify a food's taste. They may be natural or artificial, and include artificial sweeteners.
Colours are used to enhance the visual appeal of certain foods. Colouring agents may be used to restore colour lost in processing and to give a uniform colour to products despite natural seasonal variation.
Enhancers such as monosodium glutamate are used to increase or reduce the taste and smell of a food without imparting a flavour of their own.
Nutrients replace or enhance food value. Minerals and vitamins are added if the diet might otherwise be deficient, to prevent diseases such as beri-beri and pellagra. Vitamins may be added to food to replace those lost during processing, for example, B vitamins lost in the milling process are restored to cereal products.
Preservatives are anti-oxidants and antimicrobials that control natural oxidation and the action of micro-organisms. They slow down the rate of spoliage by controlling the growth of bacteria and fungi. See food technology.
Emulsifiers and surfactants regulate the consistency of fats in the food and on the surface of the food in contact with the air. They modify the texture of food and prevent the ingredients of a mixture from separating out.
Thickeners, primarily vegetable gums, regulate the consistency of food. Pectin acts in this way on fruit products.
Leavening agents lighten the texture of baked goods without the use of yeasts. Sodium bicarbonate is an example.
Acidulants sharpen the taste of foods but may also perform a buffering function in the control of acidity.
Bleaching agents assist in the ageing and whitening of flours.
Anticaking agents prevent powdered products from coagulating into solid lumps.
Anti-oxidants prevent fatty foods from going rancid by inhibiting their natural oxidation. They also prevent discoloration in fruit.
Humectants control the humidity of the product by absorbing and retaining moisture.
Clarifying agents are used in fruit juices, vinegars, and other fermented liquids. Gelatin is the most common.
Firming agents restore the texture of vegetables that may be damaged during processing. Potatoes, for example, may be treated with calcium salts.
Foam regulators are used in beer to provide a controlled ‘head’ on top of the poured product.
Mould inhibitors help to preserve bread.
Diet: Its Contribution to Good Health