Exploring the influence of grape tissues on the concentration of wine volatile compounds

Background and Aims Knowledge of varietal wine flavour and aroma compounds has improved, but gaps exist concerning how grape composition impacts wine style. This work aimed to explore the influence that different grape tissues can have on the volatile profiles of wines. Methods and Results Riesling and Cabernet Sauvignon berries were separated into skin, flesh and seeds. Two sets of fermentations were performed using separated tissues: one using an equal mass of each tissue and another where the amount of each tissue in 25 g of berries was fermented. When an equal mass of tissue was used, the seed-derived wines had a higher concentration of esters than that produced from other grape tissues. Those produced using skins had the highest concentration of lipoxygenase pathway-derived compounds, and, for Riesling, a higher concentration of monoterpenes. When the proportional amounts of each tissue found per berry were used, the flesh-derived wines generally had a higher concentration of many wine volatiles compared to the other tissues. This reflects the greater proportion of flesh tissue in the berry compared to skin and seeds. Conclusions Seed-derived compounds can enhance ester biosynthesis during fermentation and skins appear to have high lipoxygenase pathway activity. Nevertheless, the flesh makes up such a large proportion of the whole berry that it has the major influence on volatile profiles of whole berry fermentations. Significance of the Study Different berry tissues can alter wine composition in unique ways, and this can inform strategies to alter wine composition through vineyard management or the selection of new germplasm.