Cholesterol oxidation in lard as affected by CLA during heating – A kinetic approach

Abstract

AbstractThe objectives of this study were to determine the effect of two CLAs , 9‐cis, 11‐trans CLA and 10‐trans, 12‐cis on cholesterol degradation and cholesterol oxidation products (COPs) formation in lard during heating for varied length of time. No CLAs and approximately 1770.1 µg/mL of cholesterol were detected in lard. Additionally, there was no significant change in the level of cholesterol and COPs in lard during heating at 100°C over a period of 240 min. But, at 150 or 200°C, the degradation of cholesterol was prominent with substantial amount of COPs being formed. Formation profiles of 7‐OOH, 7‐OH, and 7‐keto at 150°C as well as 5,6‐epoxides at both 150 and 200°C were fitted by a first‐order equation, while a pseudo‐second‐order model described the kinetic pathway of 7‐OH and 7‐keto formation at 200°C. The formation of 7‐OOH at 200°C were fitted as multiple first‐order formation and first‐order degradation curves as its level reached a peak at 60 min and declined to zero. Incorporation of 100 µg/mL CLA showed antioxidant activity, whereas a prooxidant activity was observed for CLA at 500 µg/mL. The outcome of this study demonstrated the potential of CLA to be an antioxidant in oil system.