Catechin/Tannin "Ripeness" Index
Related Documents
The ETS Phenolic Panel
The ETS grape phenolic extraction and rapid phenolic panel can be used to follow changes in grape phenolics during ripening and to characterize grapes at the point of harvest. The grape phenolic panel was used in a University of California Cooperative Extension Service project to study the effects of hang time in Napa Valley Cabernet Sauvignon. The trial, established by Ed Webber, was designed to evaluate changes in yield components and grape composition during a six to seven week period in five Napa Valley Cabernet Sauvignon vineyards.
The Catechin/Tannin Ratio
The catechin/tannin ratio has been a reliable indicator of tannin development in past studies. In this trial, the index clearly showed the effects of grape development separate from the influences of dehydration, dilution or sugar accumulation. As grapes ripen, the tannin in seeds becomes less extractable and extractable skin tannin increases. This process can be seen in the ratio of catechin to tannin (the catechin/tannin index). The index decreases as grapes ripen and extractable tannin shifts toward skin tannin.
Graphing "Ripeness"
The 2007 trial ran from September 1st through October 15th. All five vineyards were harvested on the same day each week. The catechin/tannin ratio from Vineyard "C" is displayed in graph 1 with the corresponding °Brix shown above each bar. The data from all five vineyards is presented in graph 2. All data confirm a decrease in the catechin/tannin ratio over the given time period (indicating ripening).
Harvest Tools
The catechin/tannin index is a useful tool for making harvest decisions and allows growers to follow the effects of vineyard practices on seed ripening. It provides unique information on the potential "seediness" of fermentation lots and can be used to develop fermentation or maceration programs tailored to specific grape lots. ETS will include the catechin/tannin index in all ‘Rapid Phenolic Panel’ analyses for berry and cluster samples during the 2009 Harvest season.
ETS will include the catechin/tannin index in all 'Rapid Phenolic Panel' analyses for berry and cluster samples during the 2009 Harvest season.
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Technical Bulletin - Catechin/Tannin "Ripeness" Index |
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Harvest Fee Schedule |
The ETS Phenolic Panel
The ETS grape phenolic extraction and rapid phenolic panel can be used to follow changes in grape phenolics during ripening and to characterize grapes at the point of harvest. The grape phenolic panel was used in a University of California Cooperative Extension Service project to study the effects of hang time in Napa Valley Cabernet Sauvignon. The trial, established by Ed Webber, was designed to evaluate changes in yield components and grape composition during a six to seven week period in five Napa Valley Cabernet Sauvignon vineyards.
The Catechin/Tannin Ratio
The catechin/tannin ratio has been a reliable indicator of tannin development in past studies. In this trial, the index clearly showed the effects of grape development separate from the influences of dehydration, dilution or sugar accumulation. As grapes ripen, the tannin in seeds becomes less extractable and extractable skin tannin increases. This process can be seen in the ratio of catechin to tannin (the catechin/tannin index). The index decreases as grapes ripen and extractable tannin shifts toward skin tannin.
Graphing "Ripeness"
The 2007 trial ran from September 1st through October 15th. All five vineyards were harvested on the same day each week. The catechin/tannin ratio from Vineyard "C" is displayed in graph 1 with the corresponding °Brix shown above each bar. The data from all five vineyards is presented in graph 2. All data confirm a decrease in the catechin/tannin ratio over the given time period (indicating ripening).
Harvest Tools
The catechin/tannin index is a useful tool for making harvest decisions and allows growers to follow the effects of vineyard practices on seed ripening. It provides unique information on the potential "seediness" of fermentation lots and can be used to develop fermentation or maceration programs tailored to specific grape lots. ETS will include the catechin/tannin index in all ‘Rapid Phenolic Panel’ analyses for berry and cluster samples during the 2009 Harvest season.
ETS will include the catechin/tannin index in all 'Rapid Phenolic Panel' analyses for berry and cluster samples during the 2009 Harvest season.
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