The Effects of Different Chilling Methods on Meat Quality and Calpain Activity of Pork Muscle Longissimus Dorsi

The objective of this study was to investigate the effects of conventional chilling (0 to 4 degrees C), rapid chilling (RC, 20 degrees C for 30 min, followed by 0 to 4 degrees C), and short-duration chilling (0 to 4 degrees C for 30 min, followed by 25 degrees C) on meat quality and calpain activity of pork muscle longissimus dorsi (LD). The muscle quality characteristics pH, color, cooking loss, pressing loss and tenderness, and calpain activities were measured 0-, 3-, 12-, and 24-h postmortem. Results show that the RC resulted in a faster temperature decline of the muscle, and prevented the meat pH and Commission Internationale de l'Eclairage L* value from declining during postmortem aging. RC also reduced meat cooking loss and pressing loss compared with the other two chilling methods. However, the chilling methods did not significantly affect meat shear force. During the first 24-h postmortem, there was not a noticeable change in the activity of m-calpain. But mu-calpain activity decreased regardless of chilling method. In the rapidly chilled carcasses, mu-calpain activity remained the same 3- and 12-h postmortem. However, in the short-duration chilled and conventionally chilled carcasses, the activity was visibly reduced. At 24-h postmortem, no clear zones on the gel were observed in all three treatments.