Additives are generally substances which are of little or no nutritional value, but are used in the processing or storage of foods or animal feed.

Additives may be natural, nature identical or artificial. Natural additives are substances found naturally in a foodstuff and are extracted from this food to be used in another, for example beetroot juice with its bright purple colour can be used to colour other foods such as sweets. Nature identical additives are man made copies of substances that occur naturally. For example, benzoic acid is a substance that is found in nature and is made synthetically and used as a preservative. Artificial additives are substances made synthetically and are not found naturally.

Additives are used for a variety of purposes including to keep food wholesome until it is eaten, make the food look or taste better, ensure that the food is convenient to store or use, keep the price of the food competitive, make the food healthier (higher in vitamins or lower in fat) and aid in processing and manufacture.

Acidity regulators
Change or maintain the acidity or basicity of foods and include buffers, acids, alkalis, and neutralising agents.

Anti caking agents
Anticaking agents and free-flow agents are added to finely powdered or crystalline food products to prevent caking, lumping, or agglomeration.

Anti oxidants
Stop oils and fats in foods from combining with oxygen and turning rancid. Rancid fats smell and taste unpleasant and are a health risk. Antioxidants are also used in fruits, vegetables and juice to extend the shelf life.

Colours
Are used to make food look more appetising. During the processing of some food, colour can be lost so additives are used to restore the original colour, for example canned marrow fat peas. Colour additives can also be used to make the existing food colour brighter, for example, enhance the yellowness in custard. Most colours are either natural or nature identical and some colours are also vitamins, these are the only colours allowed in baby foods.

Emulsifiers
Emulsifiers and stabilisers – emulsifiers help mix together ingredients like oil and water that would normally separate; stabilisers prevent them from separating again. They are used in foods such as icecream.

Firming agents
Are added to precipitate residual pectin, thus strengthening the supporting tissue and preventing its collapse during processing.

Flavour enhancers
Are used widely in savoury foods to make the existing flavour in the food stronger. Monosodium glutamate is an example of a flavour enhancer. Salt is commonly used as a flavour enhancer for food and has been identified as one the basic tastes. Ironically, given its history, this has resulted in large sections of the developed world ingesting salt massively in excess of the required intake, particularly in colder climates where the required intake is much lower. This is believed to cause elevated levels of blood pressure in some, which in turn is associated with increased risks of heart attack and stroke.

Preservatives
Help keep food safe for longer. Consumers can buy foods in advance of using them and so do not need to shop so often, or use up food quickly and food companies can supply food in bulk, which saves transport costs. Preservatives can also help shops offer a wider variety of choice as foods can be safely imported or can be available out of season. Eating a variety of foods is important for good health.

Common preservative food additives include salt, sodium nitrate, sodium nitrite, sulfites, (sulfur dioxide, sodium bisulfate, potassium bisulfate, etc.), disodium EDTA. These function by preventing bacterial and mould growth, while antioxidants such as BHA and BHT help prevent spoilage from oxidation of food constituents. Other preservatives include formaldehyde (usually in solution), glutaraldehyde, ethanol, methylchloroisothiazolinone, and freeze drying. (Although the latter is a process, not an additive.)

Stabilisers
Emulsifiers and stabilisers – emulsifiers help mix together ingredients like oil and water that would normally separate; stabilisers prevent them from separating again. They are used in foods such as icecream.

Sweeteners
Are either intense or bulk. Intense sweeteners (for example saccharin and aspartame) are many times sweeter than sugar and so are only used in tiny amounts. This makes them suitable for use in products such as diet drinks, which are very low in energy. Bulk sweeteners (such as sorbitol) have a similar sweetness to sugar so are used in similar amounts.

Thickeners
Produce viscous solutions or dispersions and are used to impart body, improve consistency, or stabilise emulsions. They include suspending and bodying agents, setting agents, gel builders, bulking agents, etc.