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September 2016 WINES&VINES 57 PRACTICAL WINERY & VINEYARD WINEMAKING • Analysis of tannins recovered in the pomace after maceration showed that the propor- tion of tannins that could not be accounted for (based upon what was previously mea- sured in the fruit) varied as a function of fruit maturity and maceration length. This "wine matrix" effect modulating the propor- tion of retained tannins in the wine was of greater relevance in both the late-harvest and extended maceration wines. We specu- late that this wine matrix effect is a combi- nation of physical and chemical factors including physical sequestration, non-cova- lent binding of tannins by cell wall compo- nents of grape/yeast origin, precipitation and chemical modification resulting in new tannin structures that are not amenable to protein precipitation. • Descriptive sensory analysis indicated that wines made with fruit from the later har- vest date showed a prevailing and positive effect on the sensory profile of the wines over winemaking factors such as macera- tion length and EtOH concentration. Wines from late-harvest fruit had a more viscous mouthfeel, sweet taste and fruit- derived aromas than wines from early harvest fruit, which were dominated by fresh vegetal character, higher acidity and lower color saturation. • Extended maceration shifted the sensory profile toward higher astringency, lighter a n d y e l l o w e r c o l o r c o m p o n e n t s a n d cooked vegetal aromas. Chaptalization of the early harvest fruit to 24.9 o Brix before fermentation shifted the sensory profile from cooked and fresh vegetable toward sweet taste, alcoholic, floral and choco- late/caramel aromas, astringency and viscous mouthfeel. Discussion Analysis indicates that unripe Merlot grapes from the Columbia Valley AVA in Washington state were higher in seed tannins relative to ripe fruit. However, this higher seed concentra- tion did not result in enhanced tannin extrac- tion into wine, whether the alcohol content was increased to what could be achieved by longer ripening or maceration for 20 extra days, or a combination of the two. It has been postulated that seed tannins oxidize, polymerize and become progressively bound to cell wall components during ripen- ing, which renders them "less" extractable during winemaking. 13 Ripening also brings about enzymatic processes that may facilitate extraction, 17 thereby counteracting this puta- tive lower extractability due to oxidative po- lymerization. Our results indicate relatively higher extractability of grape tannins in ripe fruit than in unripe fruit. Our observation that overall tannin extrac- tion from grape (seeds + skins) varies accord- ing to the growing season is an empirical fact often observed by grapegrowers and winemak- ers. For example, in cool climates, heat sum- mation (growing degree-days, or GDD) has been positively associated with an increase in seeds per berry 9 and total tannin concentration per berry. 16 The figure "Comparing Seed Maturity and Tannins" allows us to draw interesting obser- vations. While visual seed maturity seems to be negatively correlated with seed tannin concentration, our results suggest that there is also a positive correlation between visual seed maturity and seed tannin extraction into wine. In other words, extraction of tannins from ripe seeds (in Merlot) is easier than from unripe seeds. A previous observation was confirmed: In climates such as eastern Washington state, in which the growing season is typically short but accompanied by fast accumulation of GDD, warmer years (such as 2012) lead to increased accumulation of seed tannins and lower seed maturity than cooler years. In the warmer 2012 vintage, fruit with 25 o Brix had essen- tially the same seed tannin concentration as