Sodium Chloride Diffusion during Muscle Salting Evidenced by Energy-Dispersive X-ray Spectroscopy Imaging

To better understand the relationship between the muscle structure and NaCl transfers in meat, we used energy-dispersive X-ray spectroscopy (EDS) coupled with scanning electron microscopy (SEM) to analyze brined and dry-salted rat muscles. The muscles were freeze-dried to avoid the delocalization of soluble ions that happens in regular dehydration through a graded series of ethanol. Na and Cl maps were superimposed on SEM images to combine the muscle structure and NaCl diffusion. Brining causes rapid diffusion of NaCl through the tissue. Most brine diffuses in a linear front from the muscle surface, but a small proportion enters through the perimysium network. The muscle area penetrated by brine shows heterogeneous patterns of NaCl retention, with some connective tissue islets containing more NaCl than other parts of perimysium. NaCl penetration is considerably slower after dry salting than after brining.