Isomerization of fatty acids in sunflower oil during heat treatment

Abstract

Pilot-scale treatments of sunflower oil similar to deodorization were carried out by applying steam stripping at different temperatures ranging from 179 to 282°C for 5 h. Samples were taken every half hour, and fatty acid composition was determined by gas chromatography. The results showed an increase in the relative percentage of trans linoleic acid with an increase in either time or temperature. The formation of trans linoleic acid isomers followed a zero-order reaction and the kinetic constants varied according to the Arrhenius’ law. The activation energies for the formation of the acids C18:2ct, C18:2tc and C18:2tt were calculated as 147.4, 147.8 and 146.6 kJ/mol, respectively.