Effect of Cold Plasma Combined with Modified Atmosphere Packaging on the Storage Quality of Prepared Beef

In order to develop a new active packaging technology for prepared beef, the effect of cold plasma (CP) combined with modified atmosphere packaging (MAP) with different oxygen concentrations (0%, 20%, 40%, and 60%; denoted respectively as T₁–T₄) on the safety, protein and fat oxidation, and physicochemical indicators of prepared beef during storage at 4 ℃ for up to 8 days was investigated using air packaging without CP treatment as control. The results showed that compared with the control group, CP combined with MAP significantly inhibited the growth of total viable count, lactic acid bacteria, Brochothrix thermosphacta and Pseudomonas during storage (P < 0.05), and this effect (except for Pseudomonas) increased with O₂ concentration inside the packaging. The combined treatment inhibited the increase in pH and total volatile basic nitrogen (TVB-N) content. After 8 days, moisture content and tenderness were significantly higher in groups T₁–T₄ than in the control group (P < 0.05), and groups T₃ and T₄ had the highest moisture content and the best tenderness. However, free radicals generated by CP resulted in oxidation of proteins and lipids. Thiobarbituric acid reactive substances (TBARS) value and carbonyl content in beef significantly increased with O₂ concentration inside the packaging (P < 0.05); TBARS value exceeded the limit in group T₄ on the 6^th day, while it was still below the limit in groups T₁–T₃ on the 8^th day. Oxidation caused a significantly lower redness value in groups T₁–T₄ than the control group during the late period of storage (P < 0.05), but the color of groups T₃ and T₄ was still acceptable on the 8^th day. In conclusion, CP combined with 40% O₂ MAP maintained TBARS value below the limit during the 8-day storage period, significantly inhibited the growth of microorganisms and TVB-N content, and preserved good physicochemical indexes, thereby maintaining the quality of beef.