Characterizing Environmental Drivers of Phenolic Extractability in Wine Grapes

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Commodities

• Fruits: grapes

Practices

• Crop Production: varieties and cultivars

Hybrid grapes are valuable agricultural products in the Northeast region, where European grape varieties are difficult to cultivate. They are more resistant to adverse environmental conditions, pests, and diseases. It is likely that hybrid wine grapes will become more widely adopted because their resilience makes them potent tools for addressing environmental and economic sustainability concerns in the wine industry.  Proanthocyanidins, also known as condensed tannins, are a key determinant of the quality and profitability of red wines. Low tannin extractability from hybrid grapes has been reported by repeated studies, and it represents a significant barrier to their wider adoption. Little is known about how environmental factors may influence extractability. Hybrid grape farmers are left with little guidance on how to improve the quality of their product, as existing research has focused on tannin accumulation in vinifera grapes. This study will characterize environmental drivers of tannin extractability in hybrid wine grapes. Grape samples of 2 cultivars will be collected from 5 locations in the Northeast region across 2 growing seasons. Environmental data will be provided by weather monitoring stations located within the vineyard. Tannin extractability will be determined using high performance liquid chromatography. Outreach materials will be developed with the help of the Penn State Grape and Wine Team, which hosts regular industry meetings and workshops. Knowledge on environmental drivers of tannin extractability will help farmers to develop approaches to maximize the quality and profitability of their crops.

1. To characterize environmental drivers of phenolic extractability in hybrid grapes. Tannin extractability will be measured in hybrid grape varieties using established HPLC methods. We will compare grapes from the same cultivar across different locations and vintages to assess the impact of growing region and climate on tannin extractability.
2. To examine variation in tannin extractability between vinifera and hybrid cultivars. Vinifera and hybrid grapes will be compared to determine whether there are significant differences in their response to environmental factors. Tannin extractability will be measured in hybrid and vinifera varieties using established HPLC methods. The impact of growing region and climate will be assessed, as in objective 1.