Comparison of Reverse Osmosis to Chaptalization in Press Fraction Chardonnay (2017)

The purpose of this study is to compare reverse osmosis treatments of juice to reverse osmosis treatments on wine, traditional chaptalization techniques, and no treatments at all. These techniques are commonly used in the wake of heavy rainfall events forcing winemakers to pick early. Chardonnay grapes were harvested and pressed into tank. This press fraction juice was allowed to settle overnight, and then was split into three separate lots: 1) Control, 2) Chaptalized, and 3) Reverse Osmosis Before (ROB) Fermentation. The ROB juice was concentrated 15%. After fermentation and malolactic conversion, the control lot was split into two separate barrels, and one of these received another treatment: 4) Reverse Osmosis After (ROA) Fermentation and malolactic conversion, to concentrate 15%. The juice chaptalization treatment was increased by 0.5 Brix in order to produce a potential alcohol which would mimic the ROA alcohol concentration, as opposed to the ROB alcohol concentration. Wines were bottled for the WRE right after the ROA treatment in early January. All other treatments between lots were equal. Alcohol content was highest in the ROB treatment. The ROB wine also had decreased acidity and increased pH, whereas the Chaptalized wine and the ROA wine had slightly increased acidity. Reverse osmosis may have increased the perception of Alcohol, Fruit Intensity, and other descriptors in wine relative to chaptalized wines. Generally, reverse osmosis wines were preferred to the chaptalized wine, but this may have been due to some oxidation in the chaptalized wine.  This study should be read in comparison with its sister study on free run Chardonnay.

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Comparison of Reverse Osmosis to Chaptalization in Free Run Chardonnay (2017)

The purpose of this study is to compare reverse osmosis treatments of juice to reverse osmosis treatments on wine, traditional chaptalization techniques, and no treatments at all. These techniques are commonly used in the wake of heavy rainfall events forcing winemakers to pick early. Chardonnay grapes were harvested and pressed into tank. This free run juice was allowed to settle overnight, and then was split into three separate lots: 1) Control, 2) Chaptalized, and 3) Reverse Osmosis Before (ROB) Fermentation. The ROB juice was concentrated 15%. After fermentation and malolactic conversion, the control lot was split into two separate barrels, and one of these received another treatment: 4) Reverse Osmosis After (ROA) Fermentation and malolactic conversion, to concentrate 15%. The juice chaptalization treatment was increased by 0.5 Brix in order to produce a potential alcohol which would mimic the ROA alcohol concentration, as opposed to the ROB alcohol concentration. Wines were bottled for the WRE right after the ROA treatment in early January. All other treatments between lots were equal. The ROB wine had higher alcohol content than the other wines. Lactic acid was slightly higher in the ROA wine, which also had a higher TA. The sensory results suggest that reverse osmosis can increase the perception of alcohol in wine, as well as increase acidity and other descriptive parameters. Reverse osmosis wines were generally preferred over the chaptalized wine, but this may have been due to reduction being present in the chaptalized treatment. More studies are needed to better elucidate the impact of RO on the aromatic and mouthfeel qualities of wine.  This study should be read in comparison to its sister study on press fraction Chardonnay.

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The Impact of Bloom Leaf Removal vs Veraison Leaf Removal (2017)

This study examines the impact of leaf pulling at either bloom or at veraison. The goal was to have looser clusters and smaller berries from pre-bloom leaf removal. A block of Cabernet Sauvignon (planted 2006) was divided so that every other row was a different treatment. One row had the four-most basal leaves removed at 30% bloom (mid-May), exposing the entire fruiting zone. Continuous passes were made to ensure fruit zone exposure throughout the season. Every other row had leaves removed at the start of veraison, in mid-August. Grapes were harvested and processed at the same times, and all other vineyard and winemaking treatments were identical between treatments. Each wine received a 6-day cold soak, and 25 days of total maceration. Grapes from prebloom leaf removal had lower TA, malic acid, and tartaric acid, with a similar pH to the control. Tannin was higher in grapes with pre-bloom leaf removal, but anthocyanins were lower. Pre-bloom wine chemistry was similar except for slightly lower acidity. Color intensity and tannin was also slightly increased in the pre-bloom wine, although these differences were not very pronounced. For the triangle test, of 19 people who answered, 6 people chose the correct wine (32%), suggesting that these wines were not significantly different. In general, of those who answered correctly, no preference trends could be seen between wines. For the descriptive analysis, there were no strong trends for the descriptors used in this study. Most descriptive results were mixed, but Pre-bloom leaf pulling may have had slightly lower Acidity and higher Body. It also may have had slightly less Herbaceous/Green  character, but these trends were weak. These results suggest that pre-bloom leaf removal may not always have as large of an impact as is often seen. This practice should be performed more at different sites, on different varieties, and in different vintages (perhaps rainier vintages which may benefit more from this kind of leaf pulling regimen). 

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The Impact of Crop Management Timing on Wine Quality (2017)

This study examines the impact of the date of cluster thinning on juice and wine chemistry. The goal was to attempt to dilute the impact of potassium uptake during veraison by cluster thinning at later dates, in order to keep the pH lower. A block of Cabernet Franc was cluster thinned either pre-veraison (around Mid-August), halfway through veraison (around the end of August), and post-veraison (first or second week of September). Every third row received one of these treatments, so that treatments were evenly dispersed throughout the block to minimize variation. All grapes were harvested on the same day, and all other treatments between each juice and wine lot were identical. The later the clusters were dropped, the higher the average berry and cluster weight. The later the clusters were dropped, the lower the Brix and phenolic compounds. YAN was slightly higher in later cluster thinning sweeps. In general, wine made from later cluster dropping had slightly less ethanol, and slightly higher TA and tartaric acid. Color intensity was decreased with later cluster thinning, as were most phenolic compounds. Thus, earlier cluster thinning tended to enhance grape “ripeness” characteristics. For the descriptive analysis, there was a strong tendency for the 50% veraison treatment to have higher Herbaceous/Green character (LSD=0.43). There was a slight tendency for this wine to also have higher Bitterness. Pre-veraison cluster thinning may have had higher Fruit Intensity. Post-veraison cluster thinning may have had slightly lower Overall Aromatic Intensity and Astringency. In general, the wines which were cluster thinned at 50% veraison were most preferred. These results suggest that the beneficial impacts of cluster thinning prior to veraison on chemistry may not be beneficial towards flavor profiles. However, this study should be repeated over multiple vintages, at different sites, and with different grape varieties to better understand how this timing of cluster thinning affects a Virginia appellation.

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The Effect of Leaf Removal at Bloom vs Leaf Removal at Veraison on Ripeness (2016)

This study examines the impact of removing the 4 most basal leaves from Cabernet Sauvignon vines at 30% bloom. One section of a vineyard block was not leafed at bloom, while another section underwent this leafing treatment. Both treatments received leaf-pulling at veraison. All other vineyard and fermentation practices were the same. Leaf removal at bloom appeared to slightly reduce berry weight, cluster weight, Brix, and yield. Grape phenolics and TA were slightly increased by bloom leaf removal. Wine produced with leaf removal at bloom had lower ethanol, color intensity, and tannin. Judges did not find the wines to be significantly different, and there were no strong preference trends for either wine. Early leaf removal may have had a very weak tendency to increase Overall Aromatic Intensity. The lack of differences are likely due in part to the particular vintage (weather events may have equalized the treatments) and in part due to vegetative growth reducing the effectiveness of the bloom leaf removal. More studies need to be performed in this area in order to draw more conclusions.

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The Effect of LalVigne Mature Foliar Spray on the South Side of Merlot Vines (2016)

This study examines the impact of LalVigne Mature Foliar Spray (ScottLabs) on ripeness and the chemical and sensory qualities of the South side of Merlot vines planted East-West. Every other row of a block of Merlot was sprayed at 5% veraison and 10 days later following the LalVigne spray protocol with a tunnel recycle sprayer, allowing for a treatment of sprayed Merlot and a treatment of unsprayed Merlot. Both treatments were harvested only from the South side of the vine (afternoon side) and processed identically and on the same day, but kept separate. All other treatments between projects were identical. The LalVigne spray slightly decreased tannins and anthocyanins in the grape berries. Caffeic acid was higher in wine from grapes treated with LalVigne. Tannin was also increased in wine from grapes sprayed with LalVigne, but anthocyanins were decreased. Triangle sensory testing revealed no significant differences between wines, and there was no strong preference for either wine. The sprayed wines tended to exhibit greater Fruit Intensity, but this was not a strong tendency.

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The Effect of LalVigne Mature Foliar Spray on the North Side of Merlot Vines (2016)

This study examines the impact of LalVigne Mature Foliar Spray (ScottLabs) on ripeness and the chemical and sensory qualities of the North side of Merlot vines planted East-West. Every other row of a block of Merlot was sprayed at 5% veraison and 10 days later following the LalVigne spray protocol with a tunnel recycle sprayer, allowing for a treatment of sprayed Merlot and a treatment of unsprayed Merlot. Both treatments were harvested only from the North side of the vine (morning side) and processed identically and on the same day, but kept separate. All other treatments between projects were identical. The LalVigne spray slightly increased tannins and anthocyanins in the grape berries, but lowered cluster weight (although not berry weight). Anthocyanins were decreased in the wine from grapes treated with the LalVigne spray. Triangle sensory testing found significant differences in the wines (p<0.05), although there was not much of a preference for one wine over the other. No major descriptive sensory trends can be seen.

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The Effect of LalVigne Foliar Spray on Cabernet Franc (2016)

This study examines the impact of LalVigne Foliar Spray (ScottLabs) on ripeness and the chemical and sensory qualities of Cabernet Franc. Every other row of a block of Cabernet Franc was sprayed at 5% veraison and 10 days later following the LalVigne spray protocol with a tunnel recycle sprayer, allowing for a treatment of sprayed Cabernet Franc and a treatment of unsprayed Cabernet Franc. Both treatments were harvested and processed identically and on the same day, but kept separate. All other treatments between projects were identical. The LalVigne spray slightly increased phenolics in the grape berries, but lowered cluster weight (although not berry weight). The LalVigne spray also increased YAN in juice. No chemical or phenolic parameters were very different in the wine. For the triangle test, of 20 people who answered, 12 people chose the correct wine (60%), showing a statistically significant difference between wines (p<0.05). These wines were voted to have an average degree difference of 4.2 (out of 10) among those who correctly identified it, suggesting that the wines were moderately different. In general, people who answered correctly had no preference for one treatment over another. There were no strong trends with regard to the descriptors used in this study.

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