Lipid oxidation in the skin during storage of fish in the round at - 5.DEG.C and the susceptibility predictable for lipid oxidation.

Abstract

The present study is concerned wity the pattern of lipid oxidation in the various tissues during the storage of fish in the round at -5°C and with the practical method to evaluate, in advance of the storage, a tendency of the fish to become rancid. Preferntial lipid oxidation was observed in the skins during the storage of fatty fish such as pacific mackerel, sardine and horse mackerel. Difference in lipid oxidation among the various tissues was due not to their lipid contents and fatty acid compositions but to the stability of their extracted lipids; thus preferential lipid oxidation in the skins was attributed to the property of skin lipids liable to autoxidize. The susceptibilities of the fresh skins, TBA37°C-2h were low in comparison with those of other tissues owing to some physical protective action against lipid oxidation, however, they were enhanced during the storage. Homogenates of the fresh various skins were incubated at 60°C for 2h, and then their susceptibilities, TBA60°C-2h were measured. TBA60°C-2h was markedly enhanced in the skins. An approximately linear relationship existed in the skins between TBA60°C-2h and lipid oxidation during the storage (r=0.93). Thus a tendency toward lipid oxidation in both lean and fatty fish was able to be predicted in advance of the storage by measuring TBA60°C-2h of the fresh skins.