Revealing the heat-induced cis-trans isomerization of unsaturated fatty acids in camellia oil

The regularity of cis -trans isomerization of unsaturated fatty acids in camellia oil under heating was revealed adopting fatty acid profile evolution coupled with reaction kinetics. The temperatures of generating mono-trans linoleic acids (C18:2-9c12t and C18:2-9t12c) and linolelaidic acid (C18:2-9t12t) were at 220 degrees C and 280 degrees C respectively, both of which were significantly higher than that of elaidic acid (180 degrees C). And the total trans fatty acids (TFAs) content was increased with the elevating of heating temperature. Furthermore, the reaction rate constants (k) of cis -trans isomerization were observed according to the rate equations. In accordance with the k, the activation energy (Ea) of the cis -trans isomerization was calculated referring to the Arrhenius equation, the Ea of generating elaidic, mono-trans linoleic and linolelaidic acids reactions were 97.22 kJ/mol, 127.4 kJ/mol and 112.6 kJ/mol, respectively. These results indicated that oleic acid is more prone to be converted into trans isomer than linoleic acid, the mono-trans linoleic acids are the precursors of linolelaidic acid in heat-induced camellia oil. This study provides a reference for the potential inhibition of TFAs formation during camellia oil processing.