Analysis of moisture changes of pork during postmortem aging by low-field NMR

In order to investigate the moisture changes of pork with different water holding capacity during aging, a total of thirty Duroc×Large White×Landrace pigs were used in this study by using low-field nuclear magnetic resonance (LF-NMR) , and transverse relaxation time and water propotion of different phase water were analysed.In the present investigation, three peaks were identified in pork during aging through the multi-exponential fitting of the bulk NMR T₂transverse relaxation time data.The peaks were directly related to three water components T₂₁ (2.127～2.541 ms) , T₂₂ (31.248～48.817 ms) and T₂₃ (167.086～275.782 ms) .Compared with low WHC group, T₂₂, T₂₃and P₂₃decreased significantly in high WHC group, while P₂₂increased dramatically, T₂₁and P₂₁was not significantly different from the three groups.During postmortem aging, the general trend of T₂₂and T₂₃increased firstly and declining, and reached the highest value at 8 h postmortem, the water molecules mobility of immobilized water and free water had the same trend, while T₂₁changed little.The proportion of free water P₂₂increased initially and then decreased during aging, while the opposite trend was detected for the proportion of free water P₂₃.The NMR images showed that the brightness of pork increased during aging.The results was of important significance to study the moisture changes of pork during postmortem aging, and it could provide theoretical basis for explain the mechanism of water holding capacity of meat.