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

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.