Description of volatile compounds generated by the degradation of carotenoids in paprika, tomato and marigold oleoresins

Here we describe the profiles of volatile compounds from the thermal degradation of carotenoids present in oleoresins of marigold, tomato and paprika. The profiles obtained by SPME-GC were complex, with identical compounds, such as toluene and m-xylene, being detected in all three oleoresins. Intramolecular cyclisation is proposed as the main reaction mechanism in the formation of the volatile compounds detected; this process is activated by the thermal impact generated during the processing and is followed by a reaction of elimination in the chain or a heterolytic fragmentation reaction. The presence of other compounds, such as various methyl benzaldehydes or isophorone (1,1,3-trimethyl-3-cyclohexene-5-one), also indicates the concurrence of carotenoid oxidation reactions that affect either the central polyenoic chain or the end-groups (β or ε rings). Ethanone,1-(methylphenyl), (4prime-methylacetophenone) not previously reported as a compound resulting from the thermal degradation of carotenoids, was also characterised and the same mechanism is proposed for its formation.