THE GENERATION OF NORISOPRENOID VOLATILES IN STARFRUIT (AVERRHOA-CARAMBOLA L) - A REVIEW

This paper summarizes our studies on the formation of C-13-norisoprenoid aroma substances in starfruit (Averrhoa carambola L.). The finding that the majority of norisoprenoid volatiles in starfruit are derived from glycosidically bound progenitors stimulated more intense studies into the glycosidic fraction of the fruit. In this paper the isolation and structural elucidation of several novel C-13- and C-15-norisoprenoid structures in starfruit is reported and the degradative pathways giving rise to the formation of potent starfruit aroma compounds are discussed. In the last part, attention is focused on possible pathways of carotenoid breakdown in starfruit, thus rationalizing the co-occurrence of C-13- and C-15-norisoprenoids with volatiles apparently derived from the central portion of the carotenoid chain.