| Many studies show that consumer can come out meat distinctly and would like to purchase the good beef. On the certain degree, good and bad for meat tenderness decide beef eating quality. Except for physiological factors including breed and years affect tenderness of beef, processing modes after slaughter such as electrical stimulation and chilling system also play important roles in meat tenderization. Most researchers had proved that Calpains are the proteolytic system that causes postmor-tem proteolysis and tenderization in meat. Based on preceeding researchers, the purpose of this research is to study Calpains activities of bovine M. longissimus and find conditions of purification of Calpain System by ion-exchange chromatography.DEAE-Sephacel and DEAE-Sepharose-FF were compared to quantify Calpains activities for comparative purpose. Effect of electrical stimulation and delay chilling on Calpains of boine longissimus were analyzed and the mechanism of beef aging was discussed in this paper.The major testing results as follows:1 Calpains activities of bovine M. longissimus by ion-exchange chromatography was studied. DEAE-Sephacel and DEAE-Sepharose-FF werecompared to quantify Calpains activities for comparative purpose. The results indicated that DEAE-Sepharose-FF was superior to DEAE-Sephacel.2 Calpain system purified by DEAE-Sepharose-FF column was studied. It shows that height 40cm, 2.0ml/s of velocity and two liner gradient, 0～215mM,0～235mM of density of one step can separate and purify calpains better.3 Four grope crossbred yellow cattle were slaughted according to standard slaughting practices. The results showed that electrical stimulationand delay chilling exerted positive effects onμ-calpain activity(P<0.05).So both fasted beef aging process significantly (P<0.05). Butμ-calpain gradually lost its activity with postmortem storage.4 After 1h postmortem, the results showed that electrical stimulation and delay chilling increase in the level of m-calpain compared to theinitial value(P<0.05). However, except ES&DC treatmeat declined Significantly, electrical stimulation and delay chilling exerted no significant variation in the activity of m-calpain over the first a post-mortem(P>0.05).5 After electrical stimulation and delay chilling there was a slight increase in the level of calpastatin compared to the initial value(P<0.05).Subsequenty, the post-mortem level of calpastatin declined rapidly.The rate of lowering of calpastatin was more slower thanμ-calpain lever for beef LD. So both fasted beef aging process significantly(P<0.05).However,the effects of ES&DC exerted more positive effects on calpastatin activity compared to electrical stimulation and delay chilling (P<0.05).6 The results showed that the effects of the ES&DC on calpain and calpastatin of beef was concerned to the chilling system.Delay chillingsystem improved the effect of electrical stimulation. |
