Thermally induced isomerization of linoleic acid and α-linolenic acid in Rosa roxburghii Tratt seed oil

Abstract

Rosa roxburghii seed oil is obtained from the seeds left following pressing of the juice from R. roxburghii fruit. The total oil content of R. roxburghii seed was around 9.30%. The fatty acid profile of the oil was determined by gas chromatography (GC). Among the 11 fatty acids identified in the oil, seven were unsaturated fatty acids (UFAs) (92.6%); four were saturated fatty acids (SFAs) (7.17%). Then, the kinetics of formation of trans-fatty acids was studied by GC. Heat treatment of R. roxburghii seed oil showed an increase in the relative percentage of linoleic acid and α-linolenic acid isomers with increasing temperature and time. The formation of linoleic acid and α-linolenic acid isomers followed a zero-order reaction. The presence of O2 enhanced the isomerization of these UFAs. In addition, the rate constants and activation energies for the geometrical isomerization of UFAs in R. roxburghii seed oil were presented. Overall, R. roxburghii seed oil contains high UFA contents. Heating temperature and duration and the presence of O2 should be considered to reduce the formation of trans-fatty acids during thermal treatment of R. roxburghii seed oil.