STABILITY OF β-CAROTENE IN THERMAL OILS

The isomerization and decay of beta-carotene in thermal oils were monitored using high-performance liquid chromatography and UVvis spectroscopy (UV). For the first time, the effects of temperature, dissolved oxygen, oil type and antioxidants on the stability of beta-carotene were systematically investigated by first-order kinetics. Isomerization of all-trans- to cis-isomer was a dominating reaction in the initial period (about 3 h for 140180C). Lower temperature and oil with more unsaturated fatty acids gave positive effects on the beta-carotene stability, whereas the dissolved oxygen slowed the decay rate at several conditions (150180C of soybean oil, 140180C of peanut oil and 140150C of ODO). The antioxidants significantly protected beta-carotene only when the temperature was lower than 150C, and they almost did not affect the beta-carotene stability when the dissolved oxygen was removed.