Insight into β-Carotene Thermal Degradation in Oils with Multiresponse Modeling

The aim of this study was to gain further insight into beta-carotene thermal degradation in oils. Multiresponse modeling was applied to experimental high-performance liquid chromatography-diode array detection (HPLC-DAD) data (trans-, 13-cis-, and 9-cis-beta-carotene concentrations) during the heat treatments (120-180 A degrees C) of two beta-carotene-enriched oils, i.e., palm olein and copra. The test of different reaction schemes showed that beta-carotene isomerization reactions were dominant and reversible. The resulting cis isomers and trans-beta-carotene simultaneously underwent oxidation and cleavage reactions at the same rate constant. From the kinetic analysis, it appeared that-contrary to oxidation and cleavage reactions-isomerization rate constants did not follow the Arrhenius law. However, the isomerization equilibrium constant increased with temperature, favoring isomer production, particularly 9-cis-beta-carotene. Its production was shown to be concomitant with oxidation and cleavage reactions, indicating that 9-cis-beta-carotene could be a good degradation indicator during oil storage or processing.