According to World Health Organization (WHO) food additives are substances added to food to maintain or improve its safety, freshness, taste, texture, or appearance. Food additives need to be checked for any potential harmful effects on human health before they can be used.

Food additives can be derived from plants, animals, or minerals, or they can be synthetic. They are added to foods deliberately to perform certain technological purposes. There are several thousand food additives used, all of which are designed to perform a specific job in making food safer or more appealing.

Stabilizers

These additives are used to increase viscosity of food and to stabilize the texture of food systems like ice creams. Stabilizers are generally used in the food industry to maintain the uniform texture and consistency of foods.

Preservatives

A preservative is a substance which retards deterioration or spoilage of food. There are natural (salt, sugar) and synthetic (fumaric acid, salts of benzoic acid) preservatives. These are used to increase shelf life of food products.  Preservatives can slow down the decomposition caused by micro-organisms such as bacteria. In addition to preserving the quality of the food, preservatives help control contamination that can cause foodborne illnesses.

Emulsifying agents

Emulsifiers or emulsifying agents are substances that keep ingredients and flavorings blended by holding fat (hydrophobic) on one end and water (hydrophilic) on the other end of their chemical structure. They are used in salad dressing to keep oil and vinegar from separating. There are emulsifiers which have origin from food (lecithin from soy).

Humectants

Humectants help to bind and retain water. They help in preventing foods from drying. These help in keeping foods soft and moist. Example of a humectant is sorbitol.

Anti-caking agents

Anti-caking agents are used to prevent foods in the form of powder or granules from forming lumps. They are added to baking powder, salt and other food ingredients. Calcium silicate is an anti-caking agent and when added it keeps the product which is either powder or granular free flowing.

Leavening agents

Leavening agents help creating a foam like lightness in a batter or dough that results in a soft and porous structure as in baked products such as cakes and muffins. Baking powder and yeast act as leavening agents. They produce carbon dioxide that makes dough rise otherwise the texture would be dense.

Anti-oxidants

These compounds are used to prevent oxidative rancidity of fats in food. They preserve the taste, flavor and nutritive value of the food products.  Anti-oxidants help in preventing rancidity in food products and increase shelf life.  Vitamin E is a potent anti-oxidant and t is added to many vegetable oils.

Flavoring agents

Flavoring agents are added to food to enhance aroma or taste.  Flavoring agents constitute the largest number of additives used in foods. There are hundreds of different flavor compounds used in a wide variety of foods, from cakes to soft drinks. There are natural and synthetic flavoring agents available.

WHO along with Food and Agriculture Organization of the United Nations (FAO), is responsible for assessing the risks to human health from food additives. WHO encourages national authorities to ensure those food additives in food and beverages produced in their countries to comply with permitted uses, conditions, and legislation.