二十二碳六烯酸营养强化鸡蛋及蛋黄粉中脂质分析

Analysis of lipids in docosahexaenoic acid fortified eggs and yolk powder

目的研究不同市售二十二碳六烯酸(docosahexaenoic acid,DHA)营养强化鸡蛋及蛋黄粉的脂肪酸组成以及DHA等n-3多不饱和脂肪酸的含量.方法脂质的提取采用Folch法,极性脂与中性脂的分离采用薄层色谱层析法,磷脂酶A2(phospholipase A2,PLA2)水解磷脂酰胆碱sn-2位脂肪酸,气相色谱法测定脂肪酸组成.结果市售普通鸡蛋中DHA含量为总脂肪酸的0.49%(29.19 mg/100 g鸡蛋),而4种不同品牌市售DHA营养强化鸡蛋中DHA占脂肪酸百分比分别为1.16%(111.79 mg/100 g鸡蛋)、1.86%(151.17 mg/100 g鸡蛋)、2.03%(159.46 mg/100 g鸡蛋)、5.37%(313.59 mg/100 g鸡蛋).不同品牌的营养强化鸡蛋中DHA含量差异显著(P<0.05).市售DHA蛋黄粉中DHA含量为3.35 g/100 g蛋黄粉,其磷脂中含有2.07 g/100 g蛋黄粉.PLA2水解产物表明,蛋黄粉磷脂酰胆碱中DHA连接在磷脂酰胆碱sn-2位上.结论市售营养强化鸡蛋中的DHA含量高于普通鸡蛋,不同品牌的营养强化鸡蛋之间DHA含量差别较大.蛋黄粉磷脂酰胆碱中的DHA位置连接在sn-2位上.

Objective To determine the fatty acid composition and the content of n-3 polyunsaturated fatty acids(n-3 PUFA) such as docosahexaenoic acid(DHA) of commercially available DHA fortified eggs. Methods Lipids were extracted by Folch method. Polar lipids and neutral lipids were separated by thin layer chromatography. Phospholipase A2(PLA2) hydrolyzed phosphatidylcholine to identify fatty acid composition of sn-2 positions. The fatty acid composition was determined by gas chromatography. Results The percentage of DHA was 0.49%(29.19 mg/100 g) in ordinary eggs and 1.16%(111.79 mg/100 g), 1.86%(151.17 mg/100 g), 2.03%(159.46 mg/100 g), 5.37%(313.59 mg/100 g) in 4 kinds of commercially available DHA fortified eggs, respectively. The DHA concentrations in different brands of DHA fortified eggs were significantly different(P<0.05). The DHA content in the commercially available DHA egg yolk powder was 3.35 g/100 g egg yolk powder, in which 2.07 g/100 g egg yolk power was contained in phospholipid. The results of hydrolysates of PLA2 showed that DHA in egg yolk powder lecithin was attached to sn-2 position. Conclusion The content of DHA in DHA fortified eggs is higher than that of ordinary eggs. The DHA content of different brands of nutritionally fortified eggs is quite different. The DHA in the egg yolk lecithin is mainly attached at the sn-2 position.