This paper presents the positional distribution of fatty acids in docosahexaenoic acid (22:6n-3)-rich fish oil triacyl-sn-glycerols (TG). Stereospecific analysis of TG was carried out by a nonenzymatic method. The TG of bonito head oil, obtained after a winterization process, contained 22:6n-3 at concentrations of 28,7, and 49 mole % in the sn-1, sn-2, and sn-3 positions, respectively. In the TG of oil before the winterization process, 22:6n-3 was concentrated in the sn-3 position, followed evenly by the sn-1 and sn-2 positions. Tuna orbital oil, obtained after winterization, showed the preferential association of 22:6n-3 to the sn-3 position, followed by the sn-1 position. This distribution pattern was similar to that observed for seal oil TG rather than sardine oil TG. The bonito head and tuna orbital oils are useful as fish oils with characteristics different from those of common fish oils, such as menhaden, sardine, and herring oils.
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