Proximate and Fatty Acid Compositions in Different Flesh Cuts of Cultured, Cultured Fasted, and Wild Pacific Bluefin Tuna (<i>Thunnus orientalis</i>)

Abstract

This study was carried out to determine the differences in proximate and fatty acid (FA) compositions in different flesh cuts of the most valuable cephalic portion of cultured (full-cycle), cultured fasted (full-cycle), and wild Pacific bluefin tuna (PBT; Thunnus orientalis). Cultured fasted PBTs were fasted for 6 days to ensure empty stomachs during harvesting and to determine the influence of fasting on the lipid and FA composition in different flesh cuts. Significantly higher lipid contents were observed (p < 0.05) in the dorsal akami (lean part) and the ventral o-toro (very fatty part) flesh cuts in cultured and cultured fasted PBTs than in wild ones. However, monounsaturated fatty acid (MUFA) contents in all flesh cuts were significantly higher in cultured and cultured fasted PBTs than in wild PBT. Wild PBTs contained significantly higher (p < 0.05) polyunsaturated fatty acid (PUFA) contents than other cultured PBTs in all flesh cuts except for the dorsal akami and wakaremi (fatty part near dorsal fin) flesh parts, and contained higher n-3 FA content than other PBTs—especially docosahexaenoic acid (DHA, C22:6n-3)—in the lipid fraction from the dorsal chu-toro (medium fatty part), ventral akami, ventral chu-toro, o-toro, and in dark flesh cuts. The flesh quality of cultured or cultured fasted PBTs has the advantage of having a higher total amount of essential FAs than that of wild PBT.