Effects of Oxidation in Vitro on Structures and Functions of Myofibrillar Protein from Beef Muscles

The main purpose of this study was to investigate the effects of oxidation in vitro on the biochemical properties of myofibrillar protein isolates (MPIs) from beef muscles. MPIs were incubated at 4 degrees C for 24 h with hydroxyl-radical-generating systems consisting of 0.01 mM FeCl3 and 0.1 mM ascorbic acid plus 0, 0.2, 1, 5, 10, and 20 mM hydrogen peroxide. The results showed that oxidation caused drastically structural changes in bovine MPIs. The carbonyl content, the surface hydrophobicity, and the particle diameter of MPIs were significantly increased, while the free sulfhydryl group content was dramatically decreased with increasing hydrogen peroxide concentrations. Oxidation caused the protein aggregations through cross-linking between proteins and amino acids. Proteomics study identified protein sites in which they were easy to be oxidized. Oxidized catalytic activities and binding sites of enzymes that were susceptible to oxidation were also identified.