Enzymatic carotenoid degradation and aroma formation in nectarines (Prunus persica)

C-13 norisoprenoids such as β-ionone, 3 hydroxy-β-ionone, and 3 hydroxy-5,6-epoxy-β-ionone are important carotenoid related aroma compounds in fruits. Apart from chemical degradation (photo-oxygenation, (auto)oxidation, thermal degradation), enzymatic cleavage is an important flavor formation pathway [Enzell, C. (1985). Biodegradation of carotenoids - an important route to aroma compounds. Pure and Applied Chemistry, 57(5), 693-700; Winterhalter, P., & Rouseff, R. (Eds.). (2001). Carotenoid-derived aroma compounds. ACS symposium series 802, Washington, DC: American Chemical Society (ISBN 0-8412-3729-8)]. In nectarines, the content of carotenoid degradation products depends on the degree of maturity. In fully ripened fruit up to 40% of the aglycons are C-13 norisoprenoids [Aubert, C., Günata, Z., Ambid, C., & Baumes, R. (2003). Changes in physicochemical characteristics and volatile constituents of yellow- and white-fleshed nectarines during maturation and artificial ripening. Journal of Agriculture and Food Chemistry, 51(10), 3083-3091]. Regiospecific carotenoid cleavage enzymes have been shown to be involved in aroma formation in different plants and fruits [Bouvier, F., Suire, C., Mutterer, J., & Camara, B. (2003). Oxidative remodeling of chromoplast carotenoids: identification of the carotenoid dioxygenase CsCCD and CsZCD genes involved in crocus secondary metabolite biogenesis. Plant Cell, 15(1), 47-62; Fleischmann, P., Studer, K., & Winterhalter, P., (2002). Partial purification and kinetic characterization of a carotenoid cleavage enzyme from quince fruit (Cydonia oblonga). Journal of Agriculture and Food Chemistry, 50(6), 1677-1680; Fleischmann, P., Watanabe, N., & Winterhalter, P., (2003). Enzymatic carotenoid cleavage in star fruit (Averrhoa carambola). Phytochemistry, 63(2), 131-137; Schwartz, Qin & Zeevaart, 2001]. This paper describes the isolation and partial characterization of carotenoid cleavage enzymes in nectarines, isolated from ripe skin of commercially available fruit. The enzyme is characterized by its kinetic parameters (v_max, K _m, time constant, temperature dependence, activation energy).