Harvest Decisions Based on Grape Phenolic Development (Enartis) (2017)

This study examines the ability to judge when grapes are harvest-ready by monitoring phenolic development over time. Cabernet Franc grapes began being sampled weekly starting on September 1 for a number of chemical and phenolic parameters. Enartis then made a harvest recommendation for September 22 (First Pick) based on comparing phenolic and chemical profiles over time. This decision was based on declining anthocyanin and phenolic values occurring in the grapes, with a desire to pick while these values were near their peak. The winemaker monitored grapes based on in-house chemistry values, seed coloration, and hang time, and picked another portion of the block on October 4 (Second Pick). Because the chemistry was different between juices, the second pick juice received more tartaric and malic acid additions. All other treatments were the same, except for a possible non-addition of Lafase HE Grand Cru to the second pick must. Wines were pressed off after 18-19 days. Grape ripening tended to follow classic ripening curves, exhibiting increasing Brix and a positive sigmoidal pH ripening curve. Average berry weight and water content peaked and then declined, due to dehydration. Phenolic content tended to peak and decline as well, and this occurred after the berry weight and water content began to decline. The first pick, based on phenolic ripeness, had lower alcohol. The differences in lactic acid may have been due to different malic acid additions between treatments. The first pick wine had slightly higher tannin and anthocyanin and much higher quercetin glycosides, but slightly lower color. However, this wine received Lafase HE Grand Cru, whereas the second pick wine may not have received this enzyme. This may have altered the results in this regard. Overall, sensory analysis suggests that these wines were significantly different. There tended to be a preference for the earlier picked wine, but this preference was tasting-dependent. Descriptive analysis was inconsistent between tastings, and no conclusions can be drawn with regard to this. Due to this inconsistency, this study should be repeated multiple times to help gauge the impact of picking based on phenolic parameters on sensory qualities in wine. Additionally, the use of Lafase HE Grand Cru in one wine and perhaps not in the other could have further confounded these results, suggesting that this study should be repeated. However, the idea behind this technique of monitoring ripening may serve to be a useful guide to picking in Virginia, to harvest while phenolic levels are maximized before they begin to decrease.

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Stylistic Goals of Chardonnay Based on Brix or Acidity (2015)

This experiment was designed to determine whether there is an increased balance of flavor and structure in Chardonnay when it is harvested based on acid and chapitalized, or whether it is harvested on Brix and acidulated.   The chemical differences between wines were not great.  A significant sensory difference was found between wines, with more people preferring the wine picked based on acidity.

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Hand vs. Machine Harvesting with Viognier (2015)

Machine and hand-harvested Viognier were compared for chemical and sensory differences. The machine-harvested wine had higher pH, higher volatile acidity, and lower titratable acidity.  There was a significant sensory difference between wines, with most people preferring the machine-harvested wine.  This may have been due to some oxidation that the hand-harvested wine experienced.

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Hand vs. Mechanical Harvesting with Cabernet Sauvignon (2015)

Machine and hand-harvested Cabernet Sauvignon were compared for chemical, phenolic, and sensory differences.  The machine harvested wine had higher titratable acidity and lower pH, but had less anthocyanin.  However, color intensity and hue were similar between treatments.  The sensory attributes of the wines were significantly different, with most people preferring the hand-harvested wine.  This is likely due to a Brettanomyces infection in the machine-harvested wine.

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