Protein denaturation and water–protein interactions as affected by low temperature long time treatment of porcine Longissimus dorsi

The relationship between water–protein interactions and heat-induced protein denaturation in low temperature long time (LTLT) treated pork Longissimus dorsi was investigated by combining low-field NMR T2 relaxometry with DSC measurements and measures of shrinkage of porcine Longissimus dorsi heated to 53 °C, 55 °C, 57 °C and 59 °C for either 3 or 20 h. Water within the myofibrils, measured by NMR T21 relaxation times, was affected by both temperature and holding time during LTLT treatment between 53 °C and 59 °C. The changes in NMR T21 relaxation times were associated with decreased fiber diameter and increased cooking loss, revealing a relationship between transverse shrinkage, water–protein interactions and cooking loss. DSC measurements revealed a concomitant decrease in ΔH68 °C, which suggests impact of collagen denaturation on the retention of water within the meat during LTLT treatment. Furthermore, a decrease in ΔH75 °C suggested that prolonged cooking (20 h) resulted in actin denaturation leading to decreased T21 relaxation times and higher cooking loss.