Oxidative rancidity in foods and food quality

Oxidative rancidity, one of the major causes of quality deterioration in foods, is caused by the oxidative deterioration of lipids by atmospheric oxygen. Lipids oxidize through a complex series of reactions giving rise to a myriad of non-volatile and volatile compounds that are responsible for off-flavours even at concentrations in the parts-per-billion range. This chapter provides a general overview of lipid oxidation in foods by presenting the main aspects of the oxidative development in general and, because oxidation of lipids is a complex process, for particular foods. The reaction mechanism and the principal factors affecting the rate of lipid oxidation are described. Then, the analytical methods normally applied to determine the extent of lipid oxidation, as well as accelerated methods to determine oxidative stability are presented. Finally, some recommendations are given on how to prevent or retard lipid oxidation.