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Fermentation of grapes throughout development identifies stages critical to the development of wine volatile composition

Boss, P.K., Kalua, C.M., Nicholson, E.L., Maffei, S.M., Böttcher, C., Davies, C.
Australian journal of grape and wine research 2018 v.24 no.1 pp. 24-37
cultivars, developmental stages, esters, fermentation, grapes, metabolites, small fruits, sugar content, vineyards, volatile compounds, wines, yeasts
BACKGROUND AND AIMS: Many variables affect the volatile profile of wine during production, and grape composition is an important source of varietal characters and metabolites for yeast during fermentation. In order to manage wine style through changes in grape composition, the knowledge of when important changes occur in the berries is essential. This study sought to identify stages of berry development that are most critical in defining wine volatile composition. METHODS AND RESULTS: Cabernet Sauvignon and Riesling grapes at several stages throughout development were fermented, after normalising sugar content, and the volatile compounds in the resulting wines were profiled. For both cultivars, the compounds were grouped into six clusters, which best described the changes in concentration of the volatile compounds in the wines. Some varietal compounds showed significant differences in wines made from berries at the various developmental stages; however, many fermentation‐derived volatile compounds, especially esters, were also significantly affected by berry developmental stage. CONCLUSIONS: Dynamic changes occur in the volatile profile of wines made from grapes at several stages of development, but a few common patterns of change are seen for several volatile compounds. SIGNIFICANCE OF THE STUDY: Several distinct phases of berry development associated with either an increasing or decreasing concentration of wine volatile compounds were identified, which will inform the timing of future strategies designed to alter wine composition through interventions in the vineyard.