Understanding Antioxidant and Prooxidant Mechanisms of Phenolics in Food Lipids

Phenolic compounds are secondary plant metabolites commonly encountered in fruits and vegetables. These compounds include at least one phenol group, a structure containing an aromatic benzene ring with at least one hydroxyl substituent. Phenolics have long been added to lipid foods to inhibit oxidation reactions. In recent years, phenolics have become popular bioactive ingredients in formulated foods as studies have demonstrated that these compounds are beneficial to human health. Unfortunately, many phenolics are labile to oxidation, which complicates their addition to food products. Phenolics are often degraded as a result of non-enzymatic oxidation reactions over the life of food and these reactions may compromise the oxidative stability of the surrounding food matrix under some conditions. This chapter discusses the applications of phenolics as antioxidants and bioactive ingredients in food lipids. It provides an understanding of antioxidant and pro-oxidant mechanisms of phenolics in food lipids. It is suggested to maintain the stability of phenolic compounds and to prevent potential pro-oxidative effects within the food matrix resulting from Reactive Oxygen Species (ROS) generation to deliver the benefits of phenolic compounds in lipid-based foods. A better understanding of the conditions that promote phenolic instability and the resulting ROS production, and pro-oxidant activity, will enable manufacturers to formulate stable lipid foods containing biologically significant levels of phenolics.