APPLICATION OF HIGH-PERFORMANCE SIZE-EXCLUSION CHROMATOGRAPHY TO STUDY THE AUTOXIDATION OF UNSATURATED TRIACYLGLYCEROLS

A combination of solid-phase extraction (SPE) and high-performance siz e-exclusion chromatography (HPSEC) was used to study the autoxidation of triacylglycerol (TAG) mixtures separated from low-erucic acid rapes eed oil and butter oil. The samples were autoxidized in the dark at 40 -degrees-C for four weeks. The polar compounds of the autoxidated samp les were separated by SPE (NH2 stationary phase), and the polar fracti on was further characterized by HPSEC with a series of three size-excl usion columns and an evaporative light-scattering detector. The polar fraction contained TAG polymers, polar TAG monomers (PTAG) and diacylg lycerols. Peroxide values and anisidine values of the samples were als o measured. By using three different types of TAG mixtures, it could b e demonstrated that the PTAG content of the TAGs increases during auto xidation. A slight increase was also detected in polymer content. The correlation between PTAG content and the comparative measurements was considered significant. The results indicate that the measurement of P TAG and polymeric material content by HPSEC analysis can be used when studying the autoxidation level of edible oils and in characterizing t he autoxidation products of different molecular sizes.