In Oregon, Pinot noir grape is the most widely planted grape of all varieties, accounting for over 60% of wine grape acreage. High winter and spring rainfall, and good soil properties such as high water-holding capacity, depth, and fertility result in grapevine high vegetative growth in the cool-climate viticulture region of the Willamette Valley of Oregon. However, excessive vine vigor can form high canopy density and result in fruit zone shading, which will negatively affect wine quality. Grape-derived volatile compounds are the secondary metabolites of grapevine, and are considered to be the most important factors for grape and wine aroma quality. The concentrations of volatile compounds and their precursors in grapes are highly influenced by viticultural practices. This study investigated impacts of vineyard floor management and fruit zone leaf removal management on Pinot noir grape and wine chemical and volatile composition over three growing season in western Oregon vineyards. Results showed that through growing grass on the vineyard floor can significantly reduce the vine vigor and increase concentrations of phenolics, free-form terpenoids and bound-form C13-norisoprenoids in grapes, leading to the resultant wine had less green note and higher fruity note. Fruit zone leaf removal improved sunlight exposure to the grapes. Results revealed that leaf removal treatment resulted in very few differences in vine growth or fruit composition, including total soluble solids (TSS), pH and titratable acidity (TA). However, the concentrations of volatile compounds in grapes were altered by leaf removal treatment. The 100% leaf removal treatment consistently had the highest concentrations of bound-form terpenoids, as well as free- and bound- form C13-norisoprenoids. The concentrations of free- and bound-form �-damascenone were positively correlated with sunlight exposure among three years. The results suggested that cluster zone leaf removal improved the overall quality of Pinot noir grapes, and thus positively affect the final wine quality.

Effects of viticultural practices on Pinot noir grape and wine volatile composition

247th National Meeting (2014)

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