Effects Of Low Energy Electron Beam Treatment On The Quality And Shelf Life Of Chilled Beef Steaks

In recent years,due to the increase in consumer demand for high-quality meat,the production and sales of chilled beef have increased year by year.However,beef has high nutritional value and high water activity.How to significantly prolong the shelf life of chilled beef and maximize the quality of beef has become a major challenge for the beef industry.As an effective food preservation method in the food industry,electron beam treatment can effectively inhibit the growth of microorganisms in chilled beef and prolong the shelf life of beef.However,improper electron beam treatment has a negative impact on beef,resulting in browning of beef color,producing odor,aggravating fat oxidation and protein oxidation,which will reduce the purchasing cravings of consumers.Therefore,it is necessary to develop more reasonable forms of electron beam treatment to prolong the shelf life and improve the quality of beef.In this study,vacuum packed chilled beef steaks were used as the research objects.In order to reduce the negative effects of electron beam treatment on beef quality,0.2 Me V low energy electron beam was used to treat steaks which only penetrated 300 μm of the beef steaks surface Because the penetration power of low energy electron beam is weak,the overall average absorbed dose of the beef steaks is small.In order to comprehensively evaluate and optimize the effects of low energy electron beam treatment,two normal doses of4 k Gy and 8 k Gy and two higher doses of 12 k Gy and 16 k Gy were set up to treat steaks,and unirradiated steaks were used as the control group.The beef steaks were stored at 0 ～ 4℃ for21 days after low energy electron beam treatment.The total viable count（TVC）,microbial diversity,p H value,meat color（fresh meat color,relative content of three myoglobins,R630/580 value）,TVB-N,lipid oxidation,protein oxidation,desmin degradation were measured at different storage time（1 d,7 d,14 d,21 d）,sensory evaluation was also carried out.Study on the effects of low energy electron beam treatment on the quality and shelf life of the chilled beef steaks.The main results of this study are as follows:（1）Compared with the control group,the growth of microorganisms in beef steaks were significantly inhibited by low energy electron beam treatment（P < 0.01）,and the sterilization effects were proportional to the treatment dose.The beef steaks in the control group were close to deterioration after 21 days of storage,and TVB-N was close to the limit value of cold fresh meat 15 mg/100 g.The TVC and TVB-N of beef steak treated with low energy electron beam after 21 days storage were 3.89 ～ 4.02 log CFU/g and 12.77 ～ 14.24 mg/100 g,respectively..The results showed that low energy electron beam treatment had a significant sterilization effect of the beef steaks and could effectively delay beef steaks spoilage.Low energy electron beam treatment had a significant effect on the succession of the beef steaks microbial colony structure.The succession process of the microbial community in the low energy electron beam treatment group was more complex than that in the control group beef steaks.The original microbial colonies of the beef steaks in the control group were mainly composed of Acinetobacter,Thermus and Brochothrix.With the extension of storage time,the relative abundance of Carnobacterium in beef steaks in the control group gradually increased,which became the main dominant bacteria in the later stage of storage.In the low energy electron beam treatment group,Leuconostoc became the main dominant bacteria in the later stage of storage.Low energy electron beam treatment can prolong the shelf life of the chilled beef steaks mainly by inhibiting the growth of Carnobacterium and Serratia in the later stage of storage.（2）The meat color of the control group gradually changed to brown with the extension of storage time,in the later stage of storage,the meat color of the low energy electron beam treatment group was better than that of the control group.Low energy electron beam treatment could significantly increase L* value,a* value,C* value,OMb%,R630/580 value of the beef steaks（P < 0.05）,significantly decrease h* value,MMb% of the beef steaks（P <0.05）,delay meat color browning,and had no significant effect on b* value,DMb%（P >0.05）.The flesh color score in sensory evaluation also further proves this conclusion.But the dose of 12 k Gy and 16 k Gy lightened the color of the beef steaks.During the whole storage period,the beef steaks color of the 8 k Gy low energy electron beam treatment group was significantly higher or not significantly lower than that of the control group and other treatment groups,so this does had the best effect of maintaining beef steaks color.（3）After 21 days of storage,the TBARS value of the control group was 0.38 mg/kg,while that of the low energy electron beam treatment group was the highest.There was no significant difference between the two groups（P > 0.05）,indicating that the low energy electron beam treatment had no significant effect on the degree of lipid oxidation of beef steaks.The content of sulfhydryl was negatively correlated with the degree of protein oxidation.During the whole storage time,the total sulfhydryl content and active sulfhydryl content of beef steaks in the low energy electron beam treatment group were higher than those in the control group,but there was no significant difference between them（P > 0.05）.The results showed that low energy electron beam treatment had no significant effect on the sulfhydryl content of beef steak.The odor score in sensory evaluation further proves this conclusion.Low energy electron beam treatment had no significant effect on the tenderness of the beef steaks（P > 0.05）.Only the carbonyl content index showed that the protein oxidation degree of the beef steaks was significantly increased by low energy electron beam treatment（P < 0.01）.During the whole storage period,the carbonyl content of the 8 k Gy low energy electron beam treatment group was significantly lower or not significantly higher than that of the control group and other treatment groups,so this does had better quality.Comprehensively considered,8 k Gy low energy electron beam treatment combined with vacuum packaging can not only prolong the shelf life of the beef steaks,but also maintain the color quality of the beef steaks,in the meantime,basically eliminate the adverse effect on the oxidation of the beef steaks.