A role of phospholipid in antioxygenic action of lipids from the ordinary muscle of lean fish.

In the previous paper, the authors pointed out that lipid oxidation was depressed in the ordinary muscle during storage of fish (in the round) and that the stability of lipids correlated with their contents of phospholipid (PL). The present paper deals with the participation of PL in the ordinary muscle of learn fish in lipid oxidation. Lipids from the ordinary muscle of plaice were separated into three fractions (Frs. I, II and III) by gel chromatography on Bio-Beads S-X2 wiht benzene as an eluting solvent. PL(Fr. I) was well separated from the remaining lipids. Antioxygenic action of each faction on methyl linolenate (MLn) was estimated by the measurment of residual MLn during incubation of the systmet at 40°C for 5 days in which each fraction was added to MLn. Inhibition of MLn oxidation was not observed by the addition of Fr. I but by that of whole lipid or Fr. III. Andioxidant in Fr. III was indentifiled as a-tocopherol (a-Toc) by thin layer chromatography using β-carotene-linoleate and Emmerie-Engel reagents as detectors. Addition of PL to the mixture of MLn and a-Toc prolonged induction period of MLn oxidation remarkably. The more PL added to the mixutre, the higher stability of MLn was obtained. The authors concluded that PL plays an important role on lipid oxidation in the ordinary muscle during cold storage of fish as a synergist for antioxygenic action of a-Toc.