The effect of temperature on the activity of μ- and m-calpain and calpastatin during post-mortem storage of porcine longissimus muscle

The experiment was conducted to determine the effect of temperature during post-mortem muscle storage on the activity of the calpain system, the myofibril fragmentation and the free calcium concentration. Porcine longissimus muscle were incubated from 2 h post-mortem at temperatures of 2, 15, 25 and 30 degrees C and sampling times were at 2, 6, 24, 48 and 120 h post-mortem. After 120 h at 30 degrees C the free calcium concentration increased to 530 mu M from 440 uM at 2 degrees C. Incubation at temperatures higher than 2 degrees C resulted in the appearance of autolyzed m-calpain activity and a decrease of native m-calpain activity. Native m-calpain decreased more slowly than native mu-calpain, and the autolysis process started later. Myofibril fragmentation increased with storage time and incubation temperature, while calpastatin activity decreased. The study showed that high temperature incubation not only rapidly activated mu-calpain but at higher temperatures and later time points also m-calpain. (C) 2011 Elsevier Ltd. All rights reserved.