Edible oils consist of about 96% triacylglycerides, composed of different fatty acids. Some other compounds or groups of compounds, such as free fatty acids, phospholipids, phytosterols, tocopherols, other antioxidants or waxes, can also be found. Fatty acids, free or bound to glycerol are susceptible to oxidative processes resulting in a wide range of volatile and non-volatile degradation products. Therefore one of the major challenges for the oil processing industry is to maintain the high quality of the product after processing until use by the consumer. However, the oxidative stability of edible oils not only depends on conditions during storage, but also the history of the raw material and the processing steps involved.

Oxidation processes play an important role in the deterioration of fats and oils with rancidity as the main effect. The most characteristic changes which become more and more obvious during the oxidation process are the development of an unpleasant taste and smell, but also changes in colour, viscosity, density and solubility take place. Further consequences include the loss of essential fatty acids, the degradation of vitamins and pro-vitamins, and the formation of odour-intensive compounds. These changes strongly influence the nutritional value and sensory quality of edible oils. The primary stage of the oxidation process produces hydroperoxides. As these hydroperoxides degrade, compounds are formed which are considered to have a certain toxicological potential in higher concentrations. The products of the oxidation process can react with other ingredients in complex composed foods, such as amino acids or proteins, resulting in changes of texture or colour. Therefore oxidation is very important in terms of the palatability, toxicity and nutritional value of edible oils.