Occurrence of Conjugated Cyclopropanoid Acid in Purified Fish Oil

Abstract

The presence of conjugated trienoic acids were found in the purified fish oil from the Japanese sardine by an analysis of high performance liquid chromatography equipped with a photodiode-array detector. Gas chromatography-mass spectrometry indicated that main conjugated trienoic acids were those of 16:3, 20:5, and 22:6. Conjugated trienoic acid of 16:3 was identified as a cyclopropanoid acid with conjugated triene by NMR analysis. All conjugated trienoic acids were formed by heat treatment during the deodorization of fish oil, but not found after de-gumming, alkaline refining, and bleaching. Conjugated trienoic acids of 16:3, 20:5, and 22:6 originated from 16:4n-1, 20:5n-3 (EPA), and 22:6n-3 (DHA) in the fish oil during the heat treatment for deodorization.