Protein-related changes during salting of milkfish (Chanos chanos)

Milkfish collected from brackish water culture ponds were wet and dry salted for 24 h and the dry-salted fish were sun dried for 48 h. Biochemical changes, ie changes in (alpha)-amino nitrogen, non-protein nitrogen, salt-soluble nitrogen, total free amino acids, essential amino acids and sulfhydryl groups, during salting and sun drying were studied. The reduction in these parameters was slightly higher in wet-salted fish compared with dry-salted fish. Further reduction in these parameters was noticed on sun drying of dry-salted fish. Electrophoretic studies showed a decrease in the number of bands during wet and dry salting at a slow rate up to 9 h, after which high-molecular-weight proteins decreased faster than medium-molecular-weight proteins in both the 24 h wet- and dry-salted samples. Further reduction in the number of bands and their intensity was observed on sun drying for 48 h. The medium-molecular-weight protein seems to be more stable.