COMPARISON OF OXIDATIVE PROCESSES ON MYOFIBRILLAR PROTEINS FROM BEEF DURING MATURATION AND BY DIFFERENT MODEL OXIDATION SYSTEMS

The aim of this work was to compare the oxidative processes occurring in myofibrillar proteins during meat maturation and after an in vitro exposure to different enzymic and nonenzymic oxidative systems. Myofib rils were prepared from bovine Longissimus lumborum and Diaphragma ped ialis at day 1 and day 10 post-mortem. Myofibrillar protein oxidation was measured by the carbonyl content, with the 2,4-dimitrophenylhydraz ine (DNPH) method, and by (thiol group) SH content with the 2,2'-dithi obis(5-nitropyridine) (DTNP) method. Polymerization and/or fragmentati on of oxidized proteins were estimated by SDS-PAGE and Western blot an alysis using a polyclonal antibody to myosin. Oxidation of myofibrilla r proteins is dependent upon the different metal-catalyzed oxidation ( MCO) systems. The increase in carbonyl content and also the decrease i n SH content of myofibrillar proteins, after maturation of 10 days, we re similar to those obtained after a 1 h incubation of myofibrillar pr oteins in the presence of several MCO systems. Electrophoretic studies showed that myosin was the protein the most sensitive to oxidation, a nd to a lesser extent, troponin T. Myosin-oxidative products were also detected by Western blot analysis.