Seasonal Variation on General Composition, Free Amino Acids and Fatty Acids in the Gonad of Taiwan's Sea Urchin Tripneustes gratilla

Abstract

The seasonal variation of chemical composition in sea urchin Tripneustes gratilla gonad from Taiwan is investigated. The level of both gonad index (GI) and body weight in the sea urchins showed seasonal variations and were higher during spring and summer. The main saturated fatty acids (SFA) of sea urchin gonad were C14:0 and C16:0, and both varied with season. Arachidonic acid and eicosapentaenoic acid were the dominant poly-unsaturated fatty acids (PUFA), while C16:1, C18:1 and C22:1 were the predominant monoenoic fatty acids (MFA). The levels of total fatty acids were higher in summer, and decreased to the lowest in December (13.2 ± 2.3 mg/g). The SFA level was higher in summer, while the PUFA level was higher in winter. The most dominant free amino acid (FAA) of sea urchin gonad was glycine, where alanine, proline, arginine and glutamic acid were the predominant FAAs. Arginine and valine were in increasing from September to February. Meanwhile glycine, alanine and glutamic acid also presented seasonal change. Overall, the gonad of Taiwan's sea urchin T. gratilla offered higher gonad content, better color and higher level of lipid in summer. It suggested the better period for consuming T. gratilla in Taiwan is from May to July.