Effect of Processing Methods on Protein Oxidation of Beef

In order to study the changes of protein oxidation during heat processing, cattle tendon and shoulder were treated at different temperatures (40, 50, 60, 70, 80, 90, 100 ℃, holding time 30 min) and at 70 kPa high pressure for different times (15, 20, 25, 30, 35 min). The changes of carbonyl content, sulfhydryl content, protein particle size, surface hydrophobicity, SDS-PAGE electrophoresis and protein secondary structure were analyzed. The results showed that temperature could lead to the increasing of protein carbonyl content, sulfhydryl content first increased and then decreased, protein particle size increased, protein surface hydrophobicity first increased and then decreased. High pressure resulted in the increasing of protein carbonyl content, the decreasing of protein sulfhydryl content, the increasing of protein particle size and the increasing of protein hydrophobicity. In addition, myofibrillar proteins were degraded and aggregated obviously under different heat treatments, and a large number of small molecular proteins appeared. Infrared studies showed that the secondary structure of myofibrillar protein changes during heat processing, which urged the formation of the secondary structure of myofibrillar protein α-spiral β-the conversion between folding and irregular curling. It was concluded that temperature and pressure could promote the oxidation of beef protein and change the chemical force and secondary structure of beef protein. This study would provide a theoretical basis for the industrial regulation of low-temperature beef products.