In the food industry, manufacturers use ingredients that have nutritional purposes, such as flour and sugar, but they can also use extra ingredients, that may not usually be present in the food naturally. These ingredients are food additives, and this term encompasses substances that perform different functions. Food preservatives are just one group of food additives.
Food additives and preservatives are not strictly necessary for many food products. Manufacturers use food additives to improve some facet of the food. Many different additives exist and examples include colorings and sweeteners. Additives that perform less obvious functions include emulsifiers to keep fat and water from separating, or gels to impart a stable yet soft characteristic.
Most countries have a list of substances that are permitted in the food sold in that country. In the European Union (EU), for example, the European Commission authorize safe additives. In the United States, the authority is the U.S. Food and Drug Administration. Authorities use research data on the additives to assess whether the substances are suitable for consumption at normal concentrations in foodstuffs.
Although many additives, such as colors, merely add to the visual appeal of a foodstuff, and therefore potentially increase sales, when it comes to food additives and preservatives, preservatives increase shelf-life. The amount of time a food can stay edible is important both for manufacturers' and retailers' profits and also for food safety.
Examples of chemicals that can be both food additives and preservatives include calcium propionate, sodium nitrate and citric acid. Some of these chemicals occur naturally in food, such as citric acid in oranges, but some do not, including sodium nitrate commonly found in ham. Two main roles for preservatives exist. One is to slow down microbial decomposition, and the other is to preserve the appearance of the food from age-related problems like color change.
Under some interpretations of the term food additives, substances that are both food additives and preservatives are all artificial chemicals. Traditional preservatives such as common salt, which is also known as sodium chloride, may or may not be regarded as a food additive and preservative, depending on the definitions of individual food authorities. Many foods can be perfectly edible without preservatives, such as white bread.
The reason manufacturers add preservatives to foodstuffs can be for practical reasons. A bakery, for example, that provides a supermarket with sliced white loaves, typically has to add preservatives to the bread. Bread without preservatives may last only one day, and be stale the next day, so if the consumer wants to buy a loaf that stays fresh for three days, the bread needs added preservatives.
A supermarket can also keep the bread on the shelves for longer, and does not have to throw away the leftover bread each night. A benefit to the consumer is that he or she can be sure that the bread is safe to eat until the use-by date, and does not have to buy new bread everyday. Preservatives can therefore reduce food waste and allow both the bakery and the supermarket to run more efficiently.