Antioxidant Mechanisms and Applications in Muscle Foods

Biological tissues are commonly subjected to free radical attack and subsequent oxidative damage due to imperfections in oxygen metabolism (Halliwell et al., 1995). Skeletal muscle is particularly susceptible to oxidative reactions since it contains high concentrations of lipid membrane systems (e.g. mitochondria and sarcoplasmic reticulum), prooxidants (e.g. transition metals and heme-containing proteins) and in some cases oxygen. To protect against these prooxidative conditions, skeletal muscle contains a multicomponent antioxidant system. This endogenous skeletal muscle antioxidant defense system is composed of nonenzymic antioxidants in both the cytosolic and lipid phases as well as antioxidant enzymes. Concentrations of endogenous antioxidants are a function of animal species, muscle type and in some cases diet. Endogenous antioxidants provide a natural level of oxidative stability to all muscle foods. However, meat processing operations such as size reduction, sodium chloride addition andcooking can accelerate oxidative reactions and inactivate antioxidants to the point where endogenous antioxidants cannot adequately protect the muscle. In these meat products, exogenous antioxidant additives, dietary antioxidants or food packaging techniques must be utilized to control oxidation. Control of these oxidative reactions is crucial in order to produce high-quality, wholesome meat products since oxidation causes deterioration of flavor, color and texture and the formation of potentially toxic compounds (Addis and Park, 1989; Vercellotti et al., 1992; Faustman, 1993; Xiong and Decker 1995).