Characterization of the effects of β‐carotene on the thermal oxidation of triacylglycerols using HPLC‐ESI‐MS

RP HPLC method coupled to ESI‐MS was used for the analysis and characterization of the oxidation of model triacylglycerols (TAGs) in presence of β‐carotene. β‐Carotene was added to the TAGs and oxidized in the Rancimat at 110°C. The samples were separated isocratically using a mixture of isopropanol with methanol and a Phenomenex C18 column. β‐Carotene degradation was measured using high performance TLC. We found that β‐carotene plays an important role during the thermal degradation of high oleic acid model TAGs. Half of the β‐carotene was degraded before 3 h of thermal treatment. β‐Carotene significantly increases the peroxide value of the TAGs after the third hour, suggesting a pro‐oxidant action. However, different TAGs show different activity toward thermal treatment and β‐carotene. The LLL was found to be less stable, OLL and OLO were stable till 10 and 12 h respectively, while POO, OOO, and OSO were the stable TAGs till 14 h. In TAGs, replacing linoleic acid by oleic acid, the stability of the corresponding TAG was found to increase by 2 h. A new class of oxidized TAGs was reported for the first time, together with previously reported species. The proposed mechanism of formation and identification of the newly identified species have been explained. Among the oxidized species of TAGs, mono‐hydroperoxides, bis‐hydroperoxides, epoxy‐epidioxides, and epoxides were the major compounds identified.