Research On Quality Changes Of Postmortem Tan Lamb By Using Different Conditions

We studied the Yanchi Tan lamb by measuring pH, cooking loss, water holding capacity (WHC), color, Warner-Bratzler shear force, TVB-N, TBA and the number of microbes in Tan lamb with different store conditions. Specifically, we discussed the influence of storage temperature changes on postmortem physicochemical characteristics and the influence of different chilling methods on meat quality and evaluated the effect of eviscerate stimulation and non electrical stimulation on the quality of Tan lamb. Results are as follows:In order to investigate the effect of different storage temperature (0-4 ℃,7℃ and 10℃) on physiological and eating quality of postmortem Tan lamb with dynamic physicochemical and microbial indexes (Id,3d,5d,7d,9d) during preservation. The results indicated that the quality is better with lower storage temperature. The pH value of Tan lamb muscle which were preserved at 0-4 ℃ was unstable. During 0-4 ℃, dripping loss and shearing force increased and myofibril fragmentation index(MFI) decreased. The tenderness and water-holding capacity was bad. Meat color could not last long. TVB-N and TBA-value decreased and the number of microbial had significant decresed. It could be preserved for a long time in market which commonly last for 5-7 days. The result indicated that the total number of bacterial colonies of Tan lamb, which was stored in 7℃ and 10℃ were partly deteriorated in the third day and fifth day respectively.Compared the impact of conventional chilling, 1h rapid chilling and 2h rapid chilling on Tan lamb quality showed that 1h rapid chilling lead to a decrease of pH and an increase of the pigment content and OxyMb percentage. The decrease of the MetMb percentage, dripping loss and cooking loss and improved the water holding capacity and better color have also been discovered. Rapid chilling for 1h could decrease the oxidation of fat, but had no obvious effect on tenderness. By observing of the micro-structure of meat with different chilling methods, there emerged significant micro-structure difference between groups with shorter sarcomere of the rapid chilling for 1h and 2h group, and sarcomere length was significantly shorter than conventional cooled group within one day. At the 9th day, there is no significant difference between three chilling groups in respect of the changes of micro-structure and sarcomere length.By analyzing the meat quality in 30 mins after slaughter with electrical stimulation or non-electrical stimulation on Tan lamb longissimus muscle, we found that the pH in 0.75h and 5h and 8h of electrical stimulation group after the slaughter were significantly lower than that of the contrast group; electrical stimulation group, compared with the contrast group, dripping loss and cooking loss increased and it had a negative impact on the Tan lamb retention. MFI increased significantly and shear force decreased. Seven day after storage, TVB-N content and TBA values increased significantly and fat oxidation was accelerated. Tan lamb corruption level had deepened. It showed that the electrical stimulation can improve the tenderness of Tan lamb meat, but it do not have benefit to long-term preservation.