Effect Of Medium Voltage Electrical Stimulation And Ageing On Tenderness Of Beef During Superchilled Storage

Superchilled storage is a kind of meat preservation technology that keeps meat in the range of freezing point and 1-2℃ below this.This technology can effectively extend the shelf life of the meat while maintaining the good quality of the meat.However,during the period of superchilled storage,the tenderization rate of beef is slow,which to a certain extent affects consumers’ choice of superchilled beef.Therefore,how to improve the tenderness of beef during superchilled storage has become a key problem restricting the application of superchilled storage technology in meat industry.Medium voltage electrical stimulation(about 300 V)can accelerate the process of glycolysis,shorten the ageing time,and improve the tenderness of meat.At present,it has been successfully used in the slaughtering process of beef cattle.In addition,ageing treatment is also one of the most common ways to improve the tenderness of meat,especially for tough meat such as beef.Therefore,the purpose of this study is to improve the tenderness of beef during superchilled storage by using medium voltage electrical stimulation technology and ageing treatment.In this study,the effects of medium voltage electrical stimulation(ES+NA,0.55 A,1 ms,34 s)on tenderness of beef during 24 weeks of superchilled storage were studied by using the cuts of beef carcasses without electrical stimulation(NES+NA)and non-electrical stimulated beef after 7 days of ageing(NES+A)as a control group.The experiment also set up an electrical stimulation and ageing group(ES+A)to determine the combined effect of electrical stimulation and ageing on the tenderness improvement of beef during superchilled storage.The main findings are as follows:(1)Medium voltage electrical stimulation could accelerate the decrease rate of p H value in 24 hours after slaughter,and effectively reduce the initial shear force of beef and the shear force value of beef stored to 16 weeks(P < 0.05),especially in the 8th week(the shear force value decreased by 22.05%);the ageing could also significantly improve the tenderness of superchilled beef at 0,4 and 24 weeks(P < 0.05),in which the shear force value decreased the most at the 24 th week of storage(21.16%).In addition,the combination of the two treatments can play a synergistic role in tenderization.After 4 weeks of superchilled storage,the shear force value of ES+A group had reached the acceptable level of Chinese consumers,while the ES+NA group,NES+A group and NES+NA group can reach the same tenderness level after 8 weeks,16 weeks and 16 weeks of storage,respectively.(2)Medium voltage stimulation and ageing could effectively reduce the initial mean particle size of superchilled beef(P < 0.05);and after 4 weeks storage,ageing still had improvement effect(P < 0.05).By analyzing the degradation of desmin and troponin-T,it was found that medium voltage stimulation and ageing could significantly promote the degradation of desmin(P < 0.05),the degradation of desmin in the ageing group was significantly higher than that in the non-ageing group(P < 0.05)in the early stage of storage(21 days).Although medium voltage stimulation and ageing had no significant effect on the degradation of troponin-T,both of them could promote the early degradation of troponin-T(14 days)to some extent.(3)During the storage period(24 weeks),the lipid oxidation value of the superchilled beef in each treatment group could be maintained at a low level(0.10-0.21 mg/kg).Although there are some differences in the growth rate of TVB-N value among the groups,they could reach the shelf life of 16 weeks.In addition,there was no negative effect on the water holding capacity of superchilled beef by medium voltage electrical stimulation and ageing.The total water loss of beef in the electrical stimulation group was significantly lower than that in the non-electrical stimulation group(P < 0.05),and the water holding capacity of the ES+A group was the best,followed by the ES+NA group,NES+A group,NES+NA group.In conclusion,the medium voltage stimulation combined with ageing can effectively shorten the ageing time of superchilled beef,which is an ideal way to improve the tenderness of superchilled beef.