Extraction of Phospholipids from the Unused Resources of Squid

Abstract

　An efficient method to extract phospholipids (PLs) from the residues of squid processing was studied. Considering its application to various foods, PL extraction with hexane-ethanol (HE) was tested and shown to achieve 75%-85% extraction efficiency compared to that with chloroform-methanol. Analysis of the lipid composition using thin-layer chromatography (TLC) revealed that 51.3% of lipids in the internal organs of squids (goro) were triacylglycerols (TGs), whereas PLs accounted for only 19.2%. In contrast, the lipid composition in squid arms (geso), mantle hemlines (suso), and fins (mimi) was similar. In squid arms, the TG content was extremely low at 3.3% and the PL content was as high as 50.9%. The HE extract from geso was subjected to acetone fractionation and preparative TLC to obtain highly purified PLs. The purified PLs were analyzed by reversed-phase high-performance liquid chromatography to determine the fatty acid composition and found to contain 10.8% icosapentaenoic acid and 19.0% docosahexaenoic acid, which are highly unsaturated fatty acids. When converted into the extracted amount per 1.0 kg fresh Japanese common squid, we found that 6.7 and 8.0g PLs could be extracted from goro and geso, respectively.