Study on the improvement of the oxidative stability of DHA and FPA

多不饱和脂肪酸(PUFAs)的氧化稳定性随着其不饱和度的增加而降低。但PUFAs在水溶液中的氧化稳定性与在纯净相中的氧化稳定性有很大的不同，其中22：6n-3的氧化稳定性最稳定，其次是20：5n-3、20：4n-6、18：3n-6和18：2n-6。在三酰甘油(TGS)和磷脂酰胆碱(PC)的水溶液中也观察到了同样的趋势。然而，金枪鱼眼眶脂肪中的TG比大豆油在空气中更容易被氧化鲑鱼蛋PC在水溶液中的氧化稳定性也高于大豆PC，但鲑鱼蛋PC的平均不饱和度高于大豆PC。多不饱和脂在水溶液中的氧化稳定性特征可能与脂分子的构象和/或脂质聚集体的性质有关。本研究结果对了解生物体系中多不饱和脂的氧化稳定性具有重要意义，并显示了将其分散在水溶液中保护鱼油免受氧化的可能性。

The oxidative stability of polyunsaturated fatty acids (PUFAs) decreases with their increasing degree of unsaturation.However, the oxidative stability of PUFAs in an aqueous solution was quite different from that in the neat phase, and 22 : 6n-3 was most oxidatively stable, followed by 20 : 5n-3,20 : 4n-6,18 : 3n-3,18 : 3n-6, and 18 : 2n-6, each in an aqueous phase.The same tendency was observed in the aqueous oxidation of triacylglycerols (TGs) and phosphatidylcholines (PCs).TG from orbital fat of a tuna was more susceptible to oxidation than soybean oil TG in the air, however, the former became oxidatively more stable than the latter in an emulsion.Salmon egg PC was also more stable to oxidation than soybean PC in an aqueous soution, although the average degree of unsaturation of salmon egg PC was higher than that of soybean PC.The characteristic oxidative stability of polyunsaturated lipids in an aqueous solution may be correlated with the conformation of the lipid molecule and/or the nature of lipid aggregation.The present findings will be important for undestanding the oxidative stability of polyunsaturated lipids in a biological systems and show the possibility of protection of fish oils from their oxidations by dispersing them in an aqueous solution.