Lipid oxidation in a chicken model system: Role of lipid and protein fibers

Chicken muscle model systems were exposed to varying concentrations of lipi d and protein fibers to clarify the role of these constituents in lipid oxi dation. In this study, the lipid substrates examined included triacylglycer ols, membrane phospholipid fractions, isolated phospholipid fractions, and free fatty acids. In iron-ascorbate catalyzed systems, increases in lipid c oncentration failed to lead to enhanced levels of oxidation at the examined times. Lipid was therefore not considered a rate limiting factor in the ox idation of muscle systems. Protein fibers accelerated oxidation only in sar coplasmic reticulum (SR) membrane systems when catalyzed by iron-ascorbate. Enhanced interaction of the low molecular weight iron with the membrane li pids may be responsible for this unique response. Preferential oxidation of sulfhydryl groups in protein fibers, on the other hand, could account for the antioxidant effect displayed by protein fibers in methemoglobin catalyz ed systems.