CHEMICAL, PHYSICAL, AND FUNCTIONAL-PROPERTIES OF OXIDIZED TURKEY WHITE MUSCLE MYOFIBRILLAR PROTEINS

Oxidative damage to turkey white muscle myofibrillar proteins (MP) was investigated by measuring changes in chemical, physical, and functional properties after exposure to iron or copper (25 muM) and ascorbate. Both iron- and copper-oxidized MP exhibited increased absorbance at 265 nm and carbonyl content compared to controls. Increasing the ascorbate concentration from 0 to 25 mM increased the absorbance 6.8- and 4.0-fold and the carbonyl content 2.6- and 1.9-fold for MP in the presence of iron and copper, respectively. The iron- and copper-oxidized MP showed lower solubility, gel strength, and gel water-holding capacity than controls. SDS-polyacrylamide gel electrophoresis demonstrated that both iron- and copper-catalyzed oxidation resulted in a major loss of myosin and actin with concomitant formation of protein polymers. These data suggest that the decreased functionality of proteins in muscle foods exposed to oxidative environments could be due to chemical and physical changes resulting from oxidative reactions.