精制鱼油三甘油酯时与之共存下的胆固醇的氧化分解

使用鳕鱼肝脏抽出的 ,经精制的鱼油三甘油酯、胆固醇和三油酸甘油酯纯品 ,分别组成 4组试样 :胆固醇与精制鱼油三甘油酯 (CFT) ;胆固醇与三油酸甘油酯 (CT) ;三油酸甘油酯 (TO) ;胆固醇 (CHOL) ,放置在 2 5℃干燥空气中贮存 ,定期对各组的氧吸收量进行测定 ,并对其中三甘油酯和胆固醇的氧化分解产物进行定性、定量分析。经 10 4d的贮存 ,只有CFT组的氧吸收量增加 ,并生成游离脂肪酸和胆固醇氧化物。而且胆固醇氧化物的数量 ,随着高度不饱和脂肪酸 (PUFA)和油酸的减少而增加。研究结果表明 ,水产制品中胆固醇的氧化与共存的油脂中的PUFA的氧化分解有关。

Oxidative Decomposition of Cholesterol in Coexisting Purified Fish Oil Triglycerides

Four model systems in the present study, coexisting of a mixture of purified cod liver triglycerides plus cholesterol,of a mixture of authentic triolein plus cholesterol,of triolein alone and of cholesterol alone,were stored separately at 25℃ in dry air for up to 104d The residual fatty acids of the triglycerides,and the cholesterol oxides produced,were recovered and determined Oxygen uptake remained almost unchanged for the mixture of triolein plus cholesterol No detectable amount of cholesterol oxides was produced,and the fatty acid content of the residual oleic acid,measured by an internal standard,remained almost unchanged For the mixture of cod liver triglycerides plus cholesterol,a remarkable increase in oxygen uptake was obsereved A continuous increase in the amount of cholesterol oxides was observed,accompanied by a remarkable concurrent decrease in polyunsaturated fatty acid residues,as well as of the oleic acid naturally present These results strongly suggest that cholesterol oxidation in fish products proceeds in conjunction with oxidative decomposition of the coexisting polyunsaturated fatty acids of fish oils