Inhibitory Effect of Different Biopreservatives on Repeated Freeze-thaw Oxidation in Tibetan Sheep

The objective of this study was to investigate the inhibitory effects of chitosan (CHI), lysozyme (LYS), and lactic acid bacteria (LAB) on lipid and myofibrillar protein (MP) oxidation during the repeated freeze-thaw process of Tibetan sheep meat. Five freeze-thaw cycles were conducted after spraying biopreservatives on the longest muscle of Tibetan sheep, and then the indicators of peroxide value, thiobarbituric acid value, carbonyl content, sulfhydryl content, surface hydrophobicity, turbidity, solubility, and other sample characteristics during the freeze-thaw process were measured and analyzed. The results showed that the above three biopreservatives had good effects to reduce the degree of lipid and MP oxidation in Tibetan sheep during the freeze-thaw process. Among them, lactic acid bacteria had the best effect. Following the fifth freeze-thaw cycle, compared with the control group, the peroxide and thiobarbituric acid values of the lactic acid bacteria treated group were 2.111 mmol/kg and 0.0315 mg/100 g lower than the control group, respectively. The carbonyl content, surface hydrophobicity, and turbidity were 2.720 nmol/mg prot, 12.404 μg, and 0.025 lower than the control group, respectively. The sulfhydryl content and solubility were 0.025 nmol/g and 14.25% higher than the control group, respectively. In conclusion, lactic acid bacteria effectively delayed the oxidation of lipids and MP during the freeze-thaw cycle of Tibetan sheep.