Analysis The Quality Of Lamb Meat Pre-and Post-rigor

Postmortem muscles undergo a process of rigor mortis and aging.Chilled meat is common in some western countries,while,in our country market,the proportion of hot-fresh(pre-rigor)meat consumption is higher.However,the difference in quality between pre-rigor and post-rigor meat is not clear.Therefore,in this paper,Menghan crossbred lamb was selected for the research,the key indexes reflecting the eating quality,nutritional quality,roasting quality and flavor quality of meat were determined,and the changes of lamb quality at different postmortem time(1 h,6 h,12 h,1 d,3 d,5 d and 7 d)postmortem were compared.Determine the difference of lamb quality between pre-and post-rigor.Finally,it would provide data support for the research and development of high-quality lamb.The main results were as follows:(1)The lamb before 6 hours postmortem was in the early stage of pre-rigor,the lamb 12hours-1 day postmortem was at the maximum rigid stage,the lamb at 1 day postmortem was in the stage of aging,and the process of aging was completed at 5 days postmortem.(2)The eating quality of lamb was different pre-and post-rigor.The brightness value L*of mutton shows an upward trend,and the redness value a*increases first and then decreases.The brightness value L*and redness value a*of lamb reached the highest at the 3~thh day postmortem;the water holding capacity of lamb was better pre-rigor,and the tenderness of lamb became lower after aging;for tenderness,the lamb pre-rigor is lower than that of lamb post-rigor.(3)The nutrients of lamb changes during postmortem storage.The water content of lamb was significantly higher(P<0.05)and the ratio of unsaturated fatty acid(UFA)/saturated fatty acid(SFA)was higher at the early stage postmortem(1?6 h).With the prolongation of storage time,the content of minerals(dry basis)decreased with the drop loss of lamb gradually.During the whole storage process,the content of total amino acids was not affected by the storage process.(4)The roast quality of lamb was different at different storage times postmortem.For fresh meat,the processing characteristics of lamb pre-rigor are better than those of lamb after aging.For roast meat,the water holding capacity of lamb pre-rigor was higher,and the tenderness of lamb was significantly improved(P<0.05)after aging.At the hazard level,the content of heterocyclic amine in pre-rigor roasted lamb was lower.However,there was no significant difference in sensory score between pre-and post-rigor roasted lamb.(5)During the process of rigor and aging,the types and contents of flavor compounds were different.During postmortem storage,the key flavor compounds of lamb mainly include hexanal,heptanal,octanal,nonanal,1-pentanol,1-octene-3-ol and 1-heptanol.There was no significant difference in the content of common key flavor compounds between pre-rigor(1 h postmortem)and early stage(1 d postmortem)(P<0.05),while the type and content of flavor compounds in lamb decreased at the later stage of aging(3 d and 5 d postmortem),and there was no significant difference in the content of common key flavor compounds between pre-rigor(1 h postmortem)and early stage of aging(1 d postmortem).Nonanal,octanal,1-octen-3-ol and hexanal were the main volatile flavor compounds in roasted lamb,and the total contents of compounds in roasted lamb at 3 days postmortem were higher than other time points.In conclusion:lamb meat pre-rigor has high water retention,less loss of nutrients and low content of heterocyclic amine after roasting.The contents of flavor compounds in boiled lamb were rich pre-rigor(1 h postmortem)and at the 1 d postmortem,and the contents of flavor compounds in roasted lamb were higher at the 3~thh day postmortem,while the tenderness and color of the lamb post-rigor were better.