Lowering crop levels has been one vineyard management criterion long believed to achieve high-quality grapes for fine wine. Low yields are most often achieved by removing grape clusters from the vine as some studies have shown this process results in an increase in quality-important compounds like aroma esters (florals and red fruit aromas) and anthocyanins (red pigmentation), color intensity and grape maturity. However, other studies have indicated that these differences are not always the result of thinning vines and that full crops are capable of achieving these characteristics depending on the vineyard climate, varietal, vintage and rootstock. This study sought to determine the impact of cluster thinning levels on Pinot noir wine phenolic composition and wine volatile composition. Ultimately allowing development of Pinot noir crop load metrics that are adaptable to winery site and wine quality production goals for grape and wine quality evaluations.

The results of the analysis of four vintages in four wineries demonstrated the role of cluster thinning practices on the volatile compounds of Pinot noir wine. Certain wine volatile compounds were affected by the cluster thinning treatments, but no consistent trend was found.

The impact of cluster thinning on wine volatiles was highly varied over vintages and wineries. The results suggest that factors such as vineyard location, aspect and soil, and vintage weather conditions impact the composition of phenolics and volatile aroma compounds in Pinot noir as much as cluster thinning or not. This research demonstrated that some vineyards/wineries can modify viticultural practices to increase yield without sacrificing wine quality. The economic and environmental implications of this research for certain vineyards and wineries is substantial.