MECHANISM OF FORMATION OF VOLATILE COMPOUNDS BY THERMAL-DEGRADATION OF CAROTENOIDS IN AQUEOUS-MEDIUM .1. BETA-CAROTENE DEGRADATION

The study of the degradation of β-carotene during heat treatment at 97 °C in water shows that the kinetics of degradation is the same as that observed in organic solvents. Some volatile compounds produced during this treatment have been previously identified after thermal degradation of homogeneous solutions of β-carotene or after heating of plant products. However, decanal, 4-ethylbenzaldehyde, and cetoisophorone were identified and 2, 6-dimethyldecahydronaphthalene and 2-hydroxy- 2, 6, 6-trimethylcyclohexanone were tentatively identified for the first time as degradation products of β-carotene. The influence of temperature on the production of volatile compounds and the kinetics of formation of volatile and nonvolatile compounds shows that dihydroactinidiolide is the first compound produced during heat treatment of β-carotene, its precursor probably being mutatochrome. Kinetics studies indicate that dihydroactinidiolide may also be produced through 5, 6-epoxy-β-ionone, which is an important reactional intermediate. This compound acts as precursor for different volatiles such as β-ionone, 2-hydroxy-2, 6, 6-trimethylcyclohexanone, and 2-hydroxy-2, 6, 6-trimethylcyclohexane-1-carboxaldehyde. © 1990, American Chemical Society. All rights reserved.