Relationship Between Protein Denaturation and Water Holding Capacity of Pork During Postmortem Ageing

Abstract

This study investigated water holding capacity (WHC), water distribution, and protein denaturation of pork loin chops (longissimus lumborum) packaged in polyethylene bags throughout display at 4 ± 1 °C for up to 1, 3, 5, 7 and 9 days. The drip loss of pork eventually increased following a decrease during the first 5 days of storage. Nuclear magnetic resonance (NMR) analysis revealed an increase in population of immobilized water P22 from day 1 to day 5, meanwhile a sharp decrease after 9 days was noticed. However, an opposite trend was observed for the population of free water P23. Correlation analysis indicated that myofibrillar protein solubility was negatively correlated with drip loss (p 0.05). Furthermore, the content of α-helices increased during the first 5 days of storage (p < 0.05), which suggested increased WHC during the earlier period of postmortem storage. During the subsequent postmortem storage, the content of α-helices decreased significantly (p < 0.05), while the β-sheets and β-turns increased. The maximum temperatures (Tmax) of three endothermic peaks were found to be 53.6 °C, 65.2 °C, and 77.6 °C at 1 day postmortem. A significant decrease were observed for Tmax peakI,Tmax peakII,Tmax peakIII at 9 d when compared to 1 d postmortem (p < 0.05), suggesting loss of thermal stability and protein denaturation.