The effect of salt and fibre direction on water dynamics, distribution and mobility in pork muscle: A low field NMR study

The effect of salt concentration and fibre orientation on water within the meat matrix was investigated by low-field nuclear magnetic resonance (LF-NMR), water-binding capacity (WBC), diffusion studies and histological analysis. Pork M. longissimus thoracis et lumborum samples were cured with 5.7, 15.3 or 26.3% w/w NaCl at a parallel or perpendicular fibre direction. NMR transverse (T2) relaxation identified three water components (T2b, T21 and T22) which all exhibited characteristics correlated to WBC. Results indicated that T2b increases with increasing NaCl concentration. Increasing intra-myofibrillar water and decreasing extra-myofibrillar water resulted in the highest WBC. Water diffused more quickly into the extra-myofibrillar space in samples cured at a parallel fibre direction. This water remained loosely bound in samples cured with the saturated solution (26.3% w/w NaCl) leading to decreased WBC. This study provides further information on water binding within the meat matrix by applying the results of LF-NMR to traditional water-binding theories. •This study applies LF-NMR to traditional water–protein interaction theories•Characteristics of all NMR components (T2b, T21 and T22) were correlated to WBC•Changes to bound water (T2b) were detected by LF-NMR•Increased T2b may indicate protein denaturation and salting-out•NaCl diffusion coefficient was increased by curing at a parallel fibre direction