Introduction

Autoxidation of lipids and the generation of free radicals are natural phenomena in biological and food systems. In biological systems, various biochemical defense mechanisms involving enzymes, trace minerals, and antioxident vitamins protect the cellular components from oxidative damage. In food systems, naturally occurring antioxidants impart a certain amount of protection against oxidation. However, natural antioxidants are often lost during processing or storage, necessitating the addition of exogenous antioxidants. Antioxidants effectively retard the onset of lipid oxidation in food products. In fact, antioxidants have become an indispensable group of food additives mainly because of their unique properties of enhancing the shelf life of a host of food products without any damage to sensory or nutritional qualities. The use of antioxidants dates back to the 1940s. Gum guaiac was the first antioxidant approved for the stabilization of animal fats, especially lard. The effective use of antioxidants requires a basic understanding of the chemistry oflipid oxidation, the mechanism of action of antioxidants, and other important properties such as synergism and degradation.