The biological tissues from which we derive foods are under constant oxidative stress from free radicals, reactive oxygen species and prooxidants. in response, biological tissues have developed multicomponent, multiphasic antioxidant systems to control oxidative reactions. These systems control free radicals, lipid oxidation catalysts, oxidation intermediates and secondary lipid oxidation breakdown products. Characterization of physical and chemical mechanisms which biological systems utilize to control oxidation can lead to identification of new antioxidative technologies to increase the oxidative stability of foods. (C) 1998 Elsevier Science Ltd. All rights reserved.