Influence of heat on protein degradation, ultrastructure and eating quality indicators of pork.

BACKGROUND Heating temperature is an important factor affecting meat palatability. This study aimed to evaluate the influence of heating temperature on some eating quality indicators, protein degradation and ultrastructure of pork muscle fibres and their correlations. RESULTS Cooking loss (CL) increased gradually (P < 0.05) with increasing temperature. Warner-Bratzler shear force (WBSF) increased in two separate phases from 25 to 50 °C and again from 60 to 100 °C (P < 0.05), with a steady phase from 50 to 60 °C (P > 0.05); conversely, a significant increase in pH (P < 0.05) occurred between 50 and 60 °C. Strong correlations (P < 0.01) among pH, CL, WBSF and colour parameters L* and b* were observed following the heating process. Increasing temperature induced gradual degradation of many muscle proteins, but myosin was not significantly degraded until 80 °C and actin showed no visible degradation throughout the whole heating process. Meanwhile, the structure of muscle fibres also changed significantly on heating, with sarcomeres contracting transversely and longitudinally and becoming condensed, but there was no occurrence of breakage within fibres. CONCLUSION Heating temperature has a great effect on eating quality indicators, protein degradation and ultrastructure of pork muscle fibres. .