Crop yield is widely recognized as an important factor in the quality of resultant wines, but most prior research has shown no effect of yield on wine quality. The role of yield in the sensory properties of Vitis vinifera L. cv. Cabernet Sauvignon was tested using pruning and cluster thinning to manipulate yield. Cabernet Sauvignon vines in the Napa Valley were subjected to six winter pruning treatments over two vintages and eight cluster-thinning treatments over one vintage, with thinning imposed at veraison. The treatments created yields that varied from 4.3 to 22.2 t/ha. Descriptive analysis conducted on the resulting wines demonstrated significant differences in several sensory attributes. Analysis of variance and principal component analysis showed that the wines made from vines pruned to low bud numbers (hence "low yield") were higher in veggie aroma and flavor, bell pepper aroma, bitterness, and astringency than "high-yield" wines. Conversely, the wines made from vines pruned to high bud numbers were higher in red/black berry aroma, jam aroma, fresh fruit aroma, and fruity flavor than low-yield wines. Regression analysis showed that, in general, veggie attributes decreased in intensity and fruity attributes increased in intensity as bud number and yield increased. In contrast, there were few sensory differences detected in wines made from the various cluster-thinning treatments, although the yield range was greater in that experiment than in the pruning experiment. We conclude that Cabernet Sauvignon aromas and flavors respond to yield manipulation, but do so significantly only when yield is altered early in fruit development.
Acknowledgments: This research was funded by grants from the American Vineyard Foundation and the Viticulture Consortium. The authors thank Jay Turnipseed and Brennen Leighton for technical assistance, David Lum and Erin Peffly for sensory lab assistance, and the judges who conducted the descriptive analysis.
- Copyright 2004 by the American Society for Enology and Viticulture