Foods are biological products and, therefore, incorporate complex physical and biochemical systems. Many vegetables, fruits, and (sometimes) meat and fish are eaten raw, but in general they are cooked. And cooking induces profound chemical and physical changes. Some changes, such as the denaturation of protein and the gelation of starch, render food more digestible and are beneficial; others, by improving appearance, color, flavor, and texture, are also desirable. But some that cause heat damage to proteins, the loss of vitamins, or the formation of carcinogens on the surfaces of roast and barbecued meats are deleterious. Cooking leads to the use of one system, or a component of it, in the establishment of another. An example would be the role of egg yolks in emulsifying oil and water (vinegar) to make mayonnaise and to color it. Cooking also permits the use of major and minor ingredients and, thus, infinite variation in the final dish, but it also opens the way for the entry into food of nonfood substances derived from utensils and containers, and from the kitchen itself.

Food processors operate highly organized and sophisticated kitchens, and they apply detailed scientific knowledge of the raw materials to the production and packaging of products in response to market demands for variety, safety, wholesomeness, nutrition, and reasonable price. In effect, food processors are “super-cooks,” but if in making mayonnaise they use lecithin (emulsifier) and beta-carotene (color) instead of egg yolk, or if they add acetic or citric acids instead of vinegar, then they are using additives.

Put simply, a food additive is a substance deliberately added to food by the processor to facilitate processing or to improve appearance, texture, flavor, keeping quality, or nutritional value. By contrast, any unwanted substance that finds its way into food is a contaminant. This may be defined even more widely as a substance that is not normally present in that food in its natural form; or is present in concentrations not normally found; or is not permitted under the food regulations to be present; or, being an additive as defined under the regulations, exceeds the concentration permitted.