Study On Formation Mechanism Of Trans Fatty Acids Of Trilinolein Under High Temperature Conditions

We often use the heated oil in the food cooking during daily life to obtain a better taste and higher flavor of processed foods.Because the oxidative cleavage reaction of food can cause trans fatty acids and a variety of structural volatile aldehydes,and more intake of trans fatty acids and aldehydes compounds may lead to the occurrence of coronary heart disease.Therefore,the detection of trans fatty acids and research of mechanism is imperative.The trilinolein at two range temperatures(100,140,180,220? and90,92,94,96,98 ?)for 1h,3h and 5h were analyzed to study the formation of saturated fatty acids,unsaturated fatty acids at high temperature by gas chromatography and to study the determination of volatile aldehydes produced under a high temperature by reversed phase high performance liquid chromatography.The corresponding bond length,the dihedral angle,activation energy and BDE were obtained and saturated acid(C16:0 and C18:0)and unsaturated acid(C18:1-9c?C18:1-9t?the isomers of C18:2)were optimized at B3LYP/6-31G*level for the density functional theory.The distribution of aldehyde compounds was analysed to detect the generation of trans-2-Hexenal,Hexanal,trans-2-Nonenal,2,4-Decadienal,2-Decenal at high temperatures by reversed-phase high performance liquid chromatography.When the heating temperature increased to 92 ?,the amount of C18:2t9cl2 was increased to 120.560 ?g/mg.The reaction rate of C18:2-9t12c is 8.550×10-8mol/s.The results show that the cis to trans isomerization may occur at 92?.Combining the theoretical calculation with the experimental data,the DFT calculation was used as a expression of the experimental data.So two kinds of oxidation pathways and the dynamic changes of linoleic acid in the high temperature were deduced.Linoleic acid will firstly isomerizate and transit linoelaidic acid(C18:2-9cl2t)at high temperatures.When the balance of the isomerization of linoleic acid and it begans to transform to monounsaturated fatty acids.These findings suggest linoelaidic acid is not the main source of trans fatty acids(TFA)in the daily diet.