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 ΔH(68 °C), which suggests impact of collagen denaturation on the retention of water within the meat during LTLT treatment. Furthermore, a decrease in ΔH(75 °C) suggested that prolonged cooking (20 h) resulted in actin denaturation leading to decreased T₂₁ relaxation times and higher cooking loss.