The potential aroma and flavor compounds in Vitis sp. cv. Koshu and V. vinifera L. cv. Chardonnay under different environmental conditions
ABSTRACTO_ST_ABSBACKGROUNDC_ST_ABSKoshu, a hybrid of Vitis vinifera L. and V. davidii Foex, is the most popular indigenous cultivar for wine production in Japan. However, little is known about the potential aroma compounds it contains and how environmental factors affect these. In this study, we obtained comprehensive profiles of the volatile (both glycosidically bound and free) and phenolic compounds that occur in Koshu berries, and compared these with similar profiles for V. vinifera cv. Chardonnay. We then compared the response of these two cultivars to bunch shading and the ripening-related phytohormone abscisic acid (ABA).\n\nRESULTSKoshu berries contained significantly higher concentrations of phenolic compounds, hydroxycinnamic acid derivatives, and some volatile phenols, such as 4-vinyl guaiacol and eugenol, than Chardonnay berries, which are thought to contribute to the characteristics of Koshu wine. In addition, Koshu berries had a distinctly different terpenoid composition from Chardonnay berries. Shading reduced the concentrations of norisoprenoid in both cultivars, as well as several phenolic compounds particularly their volatile derivatives in Koshu. The exogenous application of ABA induced ripening and increased the concentrations of lipid derivatives, such ashexanol, octanol, nonanol, and 1-octen-3-ol. Linear discriminant analysis showed that the aromatic potential could be discriminated clearly based on cultivar, bunch shading, and ABA application.\n\nCONCLUSIONThe unique secondary metabolite profiles of Koshu and their different responses to environmental factors could be valuable for developing various styles of Koshu wines and new cultivars with improved quality and cultural characteristics.