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C. M. LIYANA-PATHIRANA¹, F. Shahidi², A. Whittick³, and R. G. Hooper³. (1) Department of Biology, Memorial University of Newfoundland, St. John's, NF A1B 3X9, Canada, (2) Department of Biochemistry, (3) Department of Biology

Green sea urchins (Strongylocentrotus droebachinensis) are found abundantly in Newfoundland waters. However, sea urchins are not widely consumed in North America and there is a great potential for taking full advantage of entering the lucrative markets in Japan and Europe.

The objective of this study was to investigate seasonal changes in total lipid content, free fatty acid composition and lipid classes of sea urchin gonads .

The total lipids of sea urchin gonads were extracted using chlroform-methanol (1:1 v/v). The fatty acid compositions were determined using gas chromatography. Lipid classes were quantified using thin layer chromatography-flame ionization detection (TLC-FID).

The total lipid contents of gonads harvested in August and November were 5.3 and 2.9%, respectively. Though, there was a marked difference in the total lipids of samples harvested during August and November, their fatty acid compositions were similar. During the summer (August) gonadal lipids contained 47.4% polyunsaturated fatty acids (PUFAs) of which 30.5% were eicosapentaenoic acid (EPA). The PUFA content of sea urchin gonads harvested in the fall (November) was 47.5% with 37.1% EPA. The docosahexaenoic acid (DHA) contents in summer and fall were 3.1 and 7.6%, respectively. The non-polar lipid fraction for sea urchins collected in August contained 53.6% triacylglycerol, 33% free fatty acids and 13.4% diacylglycerol with traces of monoacylglycerol and cholesterol. Samples from the November harvest contained 66.9% triacylglycerol, 17.9% cholesterol and 15.2% monoacylglycerol as well as traces of free fatty acids and diacylglycerol. Meanwhile the polar lipid components in August harvested samples were primarily composed of 60.3% phosphatidylinositol, 30.3% phosphatidylserine/phosphatidylethanolamine, 5.7% phophatidic acid and 3.8% sphingomyelin. The corresponding values for samples harvested in November were 62.1, 25.8, 11.3 and 0.7%.

These results signify that sea urchin gonads serve as an excellent source of PUFA as EPA, but are somewhat affected by seasonal variations.