Effect of oxygen on isomerization of β-carotene during thermal treatment

All-trans-β-carotene was isomerized by heating, and followed by degradation. The isomers produced with and without oxygen identified were 15-cis-, 13-cis-, and 9-cis-β-carotene. The presence of oxygen accelerated the isomerization of all-trans-β-carotene more rapidly in the initial heating period than that in absence of oxygen. After 30 min heating, more than 90% of all-trans-β-carotene and its isomers were destroyed with and without oxygen. The changing patterns of content and proportion of carotene isomers during heating were not different from each other regardless of the presence of oxygen.