LCMS-IT-TOF测定不同脂肪酸结构食用油中的羰基化合物

Determination of Carbonyl Compounds in Edible Oils with Different Fatty Acid Compositions by LCMS-IT-TOF

为研究高温加热过程中食用油脂肪酸组成与羰基化合物形成的关系,先将三种食用油(油茶籽油、玉米油和亚麻籽油)在180℃高温加热24 h,然后采用气相色谱仪(GC)测定加热后油样中脂肪酸组成,采用高效液相色谱-离子阱-飞行时间质谱仪(LCMS-IT-TOF)测定油样生成羰基化合物组成。结果表明:油茶籽油(含有79.08%油酸)中特征羰基化合物为辛醛、壬烯醛、壬醛、癸烯醛、十一烯醛;玉米油中(含有55.05%亚油酸)特征羰基化合物为戊醛、戊酮、己醛、庚烯醛、癸二烯醛;亚麻籽油中(含有56.57%亚麻酸)特征羰基化合物为丙醛、丙酮、丁醛、丁酮、庚二烯醛。该结果表明脂肪酸组成对油脂加热所产生的羰基化合物种类起决定性作用,油酸氧化主要在8、9、10、11号碳位产生氢过氧化物,亚油酸主要在9、12、13、14号碳位产生氢过氧化物,亚麻酸主要在12、15、16号碳位产生氢过氧化物。氢过氧化物继续裂解产生不同的羰基化合物。

The purpose of the experiment was to investigate the relationship between the fatty acid composition of edible oil and the formation of carbonyl compounds during high temperature heating. First,three kinds of edible oils(camellia seed oil,corn oil,flaxseed oil)were heated in an oil bath at 180 ℃ for 24 hours. Then the fatty acid contents of them were determined by gas chromatography(GC). Meanwhile,the heated sample were subjected to a derivatization reaction by 2,4-dinitrophenylhydrazine(DNPH)and then measured by high performance liquid chromatography-ion trap time-of-flight mass spectrometer(LCMS-IT-TOF). The results showed that the characteristic carbonyl compounds of camellia seed oil(containing 79.08% oleic acid)were heptanal,octanal,nonenal,nonanal,decenal and undecenal;the characteristic carbonyl compounds of corn oil(containing 55.05% linoleic acid)were Valeraldehyde,pentanone,hexanal,heptenal and decadienal;the characteristic carbonyl compounds of flaxseed oil(containing 56.57% linolenic acid)were propanal,acetone,butanal,butanone and heptadienal. This result indicated that the types of carbonyl compounds produced by oil heated in a high temperature were determined by the type of fatty acid. Oleic acid mainly produced a hydroperoxide at the No.8,9,10,and 11 carbon positions;linoleic acid mainly produced a hydroperoxide at the No.9,12,13,and 14 carbon positions;linolenic acid mainly produced a hydroperoxide at the No.12,15,and 16 carbon positions. Different carbonyl compounds were produced by hydroperoxide continued to cleave.