Generation of saffron volatiles by thermal carotenoid degradation.

Generation of volatiles by thermal treatments has been studied in saffron spice for two reasons: (a) to determine volatile profile changes during simulated aging processes and (b) to study the volatile generation pathway. During the aging process, while the amounts of C10 compounds such as safranal and HTCC increase, the amounts of C9 compounds such as isophorone and 2,6,6-trimethylcyclohexane-1,4-dione decrease. A new compound tentatively identified as 4,5,6,7-tetrahydro-7,7-dimethyl-5-oxo-3H-isobenzofuranone seems to play a very important role in the aging process. The importance of this compound, structurally similar to dihydroactindiolide, was also confirmed when the saffron volatile fraction was analyzed via the degradation of the linear chain of crocetin and crocetin esters and is reported for the first time in this paper. Thermal degradation studies of zeaxanthin, crocetin, and trans and cis crocetin esters isomers allowed us to propose different mechanisms which explain saffron volatile generation depending on the crocetin ester isomer structure.