This study examines the impact of different turbidity levels in Sauvignon blanc juice on aroma development. Sauvignon blanc for this study was all harvested on the same day from the same block at Veritas. The grapes were destemmed and cold soaked at 45°F for 19 hours with 35ppm liquid sulfur dioxide and pressed the following day. Only free run juice was used. After the juice was pressed off Cinn-Free was added at a rate of 1.6ml/hL. The juice was settled for two days and then racked off of juice lees and inoculated with X-5 Yeast. At this point lees were added to two of the barrels to two levels of NTU (65.8 NTU and 195 NTU), while the third barrel kept the naturally occurring NTUs of processing (19 NTU). After fermentation the wine was allowed to settle and then was racked off of fermentation lees before barreling into three identical neutral barrels. At racking the medium and high rates of turbidity were combined, for two total treatments: 1) a low turbidity treatment and 2) a high turbidity treatment. No major differences in wine chemistry resulted from the turbidity differences. Thiol parameters may have slightly increased in the higher turbidity treatment. Overall, winemakers were able to distinguish statistically significant differences between wines (p<0.001). This may have been due to slight turbidity differences present in the glasses. No strong trends could be seen with the descriptors used in this study.
This study examines the impact of different desiccation sprays on the resulting juice and wine chemistry of Merlot. 8 rows of Merlot from the same block were divided into 4 pairs, each pair of rows receiving a different treatment. The following treatments were performed: 1) Control (no spray), 2) RG 1950 spray in collaboration with Dr. Mizuho Nita, where rows were sprayed 4 times weekly, over four weeks, starting from veraison, 3) VT Tech Dehydration spray in collaboration with Dr. Bruce Zoecklein, where rows were treated on the fruit zone at approximately 19 degrees Brix using a 2% solution of methyl esters of fatty acids in a 2% solution of potassium carbonate in water, and 4) Sugar Express (Miller Chemical) Spray (4-10-40 Nitrogen-Phosphate-Potash), where rows were treated on the full canopy at approximately 19 degrees Brix at 10 lbs/acre. All other viticultural and winemaking practices were equal. Grapes were harvested on September 20, after processing musts were inoculated with D21, and each fermentation received a 16 day maceration. The two VT sprays had the greatest impact on Brix and Average Berry weight during ripening. Fluctuations are due to rain events around September 2 and September 6. The VT sprays produced juice with higher Brix, although the Zoecklein spray had higher TA and the RG 1950 had lower TA. Wine chemistry showed higher ethanol for these two sprays, higher TA and tartaric acid for all three sprays, and lower levels of lactic acid. Color intensity was increased by the desiccation sprays. Anthocyanins were slightly lowered for the VT sprays, although polymeric anthocyanin was increased for these sprays. Tannin showed slight increases for these sprays as well. These phenolic differences, however, were not very great.
Overall, the desiccation sprays had a tendency to lower the Herbaceous character of the wines. Overall Aromatic Intensity and Body tended to be increased by the Zoecklein spray, although RG 1950 also had a slight tendency to increase Body. These two sprays also had a slight tendency to increase Fruit Intensity, although this was weak. In general, the control wine was more similar to the Sugar Express treatment, and the two Virginia Tech desiccation sprays were more similar to each other. Preference trends were hard to determine, but the Sugar Express treatment tended to be less preferred. The two Virginia Tech desiccation sprays were perhaps slightly more preferred control when considering that these two wines were fairly similar to each other. These results suggest that desiccation sprays may be a valuable tool in Virginia winemaking, and studies like these merit more rigorous analysis, especially with regard to sensory attributes of the wines. These studies should be continued to be repeated, on multiple varieties over multiple vintages.
This study examines the impact of vineyard desiccant sprays on grape ripening and wine quality in Cabernet Franc. A block of Cabernet Franc was divided so that part of the block was backpack-sprayed with a desiccant spray (2% solution of methyl esters of fatty acids in 2% solution of potassium carbonate in water) provided by Bruce Zoecklein. The spray treatment occurred when the grapes had reached approximately 19 Brix (September 22, 2017) and clusters were coated until dripping with spray. Grapes were harvested on September 28 and were processed identically. Wines were pressed after 11 days of maceration. Cluster weight, total anthocyanins, and tannin were decreased in sprayed fruit. Brix was increased and acidity was decreased in sprayed fruit as well. Alcohol and potassium were higher in the sprayed wine, and acidity was lowered. Color, tannin, and polymeric anthocyanin were also higher in the sprayed wine, in spite of opposite trends being seen in this regard with the grapes. Overall, these wines were found to be significantly different. There was a tendency for the desiccated wine to have higher Body. Desiccated wines had a slight tendency for higher Acidity and Astringency, and lower Fruit Intensity. However, more sensory studies are needed to confirm these trends. There may have been a very slight preference for the non-desiccated wine. In the future, more studies should be performed on fruit desiccation, as it has potential to be a useful tool in Virginia grape growing. These studies should include the timing of desiccation sprays before harvest.
Fermenting in T bins is a common practice in Virginia but may impact wine quality in ways different from fermenting in stainless steel tanks. Thus, investigating the use of these vessels is important for the Virginia wine industry. This study compares fermenting Merlot grapes in T Bins or in Stainless Steel Tanks. Merlot grapes were harvested from the same block and chilled overnight in a refrigerated truck. Grapes were then destemmed but not crushed into a 0.75 ton T Bin as well as a 3 ton stainless steel tank. Fermentations were punched down twice daily throughout fermentation and pressed off after 19 total days. Wine was settled in tank after pressing for 5 days before barreling. All other treatments between wines were identical. The area:height ratio of the tank and the T Bin are approximately 1.340m2/m and 1.355m2/m, respectively. Thus, differences seen are likely not due to dimensions. The T Bin fermentation reached higher fermentation temperatures and exhibited a slightly faster fermentation. The T Bin fermentation resulted in decreased alcohol and increased TA. The T bin had higher tartaric acid, lactic acid, and succinic acid. Color intensity and many phenolic parameters were decreased in the T Bin wine as well. For the triangle test, of 27 people who answered, 15 people chose the correct wine (56%), suggesting a statistically significant difference between wines (p<0.01). These wines were voted to have an average degree difference of 4.6 (out of 10), suggesting that the wines were moderately different. In general, people who answered correctly preferred the tank fermentation the most. For the descriptive analysis, there were no strong trends for the descriptors used in this study. There was a slight tendency for the T Bin wine to have higher Fruit Intensity and Herbaceous/Green character, and lower Bitterness, Astringency, and perhaps lower Body. Judges remarked that there may have been a strange aroma in the T Bin wine, ranging from sulfuric to volatile acidity to ethyl acetate. This may have impacted the perception of Fruit Intensity in this wine. From the chemistry, it is not clear what may be causing this aroma. These differences are hypothesized to be caused by differences in temperature and oxygen exposure between treatments, although not enough data is available to confirm or deny this. In the future this study should be repeated multiple times to gain more information and should be analyzed in more detail.
This study examines the impact of adding chardonnay lees to aging Cabernet Franc wine on mouthfeel and aroma. Cabernet Franc wine was cleanly racked into 3 separate, identical barrels on December 29, 2017 so that very little lees were transferred. Then: 1) one barrel received no addition of Chardonnay lees, 2) one received 1 liter of Chardonnay lees, approximately 1.02E6 cells/mL (Low NTU), and 3) one received 3 liters of Chardonnay lees, approximately 3.06E6 cells/mL. Lees were light lees, harvested from Chardonnay wines fermented with D254. The yeast in the lees were budding under microscope, and so 90ppm of sulfur dioxide was added to the lees before adding to barrel. The wines were stirred once every two weeks until taken for sampling in late March, 2018. No major wine chemistry differences were apparent between treatments. Sulfides were all similar between wines, with some differences in Dimethyl Sulfide. Microbial cell counts were generally higher in wine with lees additions. Color intensity was slightly lower in wine with lees added. Phenolic profiles were very similar, with perhaps a slight decrease in tannin with lees addition. Overall, low lees addition had a slight tendency to increase Fruit Intensity. Lees addition in general seemed to slightly lower Astringency. However, many of these differences were weak, and differed between tastings. The lees addition wines were generally more preferred over the control wine. This suggests that lees addition to red wines can be of benefit to red wine quality. More research with more rigorous sensory analysis is needed to further clarify what aspects of wine sensory characteristics are impacted by lees addition.
This study examines the effect of barrel stirring during aging on Cabernet Franc. Cabernet Franc wine (free run and pressings) was settled for 48 hours and then racked into two identical neutral barrels. After malolactic fermentation, barrels were sulfited and one barrel was left unstirred whereas the other barrel was stirred once per week for three months. All other treatments between wines were equal. Wine chemistry was not different between treatments. The barrel stirred wine had slightly higher levels of acetic acid bacteria, some lactobacillus species, and perhaps Saccharomyces cerevisiae. O. oeni was higher in the barrel stirred treatment as well. Tannin may have been slightly lowered by barrel stirring, and catechin may have slightly increased. Overall, the wines were not found to be significantly different. Of the people who correctly distinguished the wines, there may have been a slight preference for the unstirred wine (although the tendency to have no preference was also strong). This study should be repeated again in the future, perhaps with differing levels of lees in each treatment as well and with the turbidity measured.
This study examines the impact of micro-oxygenation in aging Tannat wine. Tannat wine was split into two identical tanks. The treatment tank was micro-oxygenated with a dosing stone through a Stavin Ox Box. Due to the small volume of wine, continuous micro-oxygenation was not possible, and instead a discontinuous regimen was put in place with a target oxygen rate of 5 mL Oxygen/L wine/month. This was achieved by dosing the wine with 0.61mL Oxygen/minute for approximately 10 hours every 3-5 days. Treatment was halted when malolactic conversion began. Chemistry results were not too different, except for sulfur dioxide binding (where more sulfur dioxide was binding in the control). Sulfides were not very different, and differences in Oenococcus are likely not due to the treatment. Color was not very different. The micro-ox wine had higher levels of anthocyanins, but slightly lower polymeric pigment and tannin. For the triangle test, of 27 people who answered, 5 people chose the correct wine (19%), suggesting that these wines were not significantly different. In fact, this suggests that judges consistently and significantly did not choose the correct wine and were biased to the replicates (p<0.05). In general, of people who answered correctly, 3 preferred the micro-ox wine, and 2 preferred the control wine. For the descriptive analysis, there were no strong trends for the descriptors used in this study. There may have been a slight tendency for the micro-ox wine to have higher Astringency, but this was very weak. These kinds of studies should be repeated in the future, over multiple varieties, utilizing both continuous and discontinuous micro-oxygenation schemes. Furthermore, more intensive micro-oxygenation regimens should be performed in future studies.
This study examines the effect of oxygenation on wines. Cabernet Sauvignon grapes were harvested and, after completion of fermentation, wine was drained and pressed into two tanks. One tank was a control, and one tank received 40 mL Oxygen/L wine/month for 3 days, and this rate was then halved every 3 days until after malolactic conversion began, where it received micro-oxygenation at 0.5 mL Oxygen/L wine/month. A third set of grapes from the same block were picked 5 days later (after a large rain event), and then received flash détente. Since malolactic conversion completed so quickly for this treatment, its oxygenation could only be at 40mL Oxygen/L wine/month for three days after draining and pressing before switching to 0.5 mL Oxygen/L wine/month. The treatments between the control and oxygenated wines were similar, but the vinification of the flashed wine was different, marked by 10 days of fermentation (compared to 14 days for the other treatments, including a 3 day cold soak). The flashed wine also had slightly different additions made. No major differences are found in wine chemistry between the control and oxygenation treatment, except for slightly higher lactic acid in the treatment. The flashed wine had higher acidity, possibly due to differential tartrate adds. The oxygenated wine had higher rates of S. cerevisiae and several Lactobacillus species relative to the control, but lower acetic acid bacteria. The flashed wine had much lower levels of acetic acid bacteria and Lactobacillus, and lower levels of S. cerevisiae as well. However, it was higher in O. oeni. Color intensity lowered among the wines from November to April; however, the oxygenated wine may have had a slight increase in color intensity relative to the control over this time (although this was weak). The oxygenated treatment had higher color intensity than the control, and the flashed wine was highest. Phenolic parameters generally decreased from November to April, and oxygenation did not appear to have much effect on the phenolic parameters. The flashed wine was much higher in catechin and quercetin and was also higher in tannin. Although it was initially lower in anthocyanin (and higher in polymeric pigment), it ended up being higher in anthocyanin.
For the triangle test, of 26 people who answered, 12 people chose the correct wine (46%), suggesting that the wines were not significantly different. In general, people who answered correctly tended to prefer the oxygenated wine, although the preference trends were somewhat complex. For the descriptive analysis, there was a strong trend for the flashed wine to have higher overall aromatic intensity than the other wines (LSD=0.97). There was a slight trend for this wine to have higher Fruit Intensity and Body, and perhaps slightly lower Herbaceous/Green character (although it was similar to the oxygenated wine in this regard). The control wine tended to have higher Herbaceous/Green character, lower Overall Aromatic Intensity, and higher Astringency (although equal to Flash in this regard). The oxygenated treatment tended to have lower Bitterness and Astringency, and perhaps lower Body as well. More studies should be performed on oxygenation, with regard to timing, amount, and with regard to continuous vs discontinuous oxygenation.
This study examines the impact of different juice clarification techniques in Pinot Gris: cold settling vs flotation. Juice from the same lot of whole cluster-pressed grapes were split into two tanks, one for cold settling and one for flotation. The cold settled juice settled for one day, whereas the floated juice was clarified overnight. All other treatments between juices and wine were equal. The acidity dropped slightly for both treatments after clarification. The cold-settled wine had a slight lag before fermentation began compared to the float. There were no major wine chemistry differences between treatments. The cold-settled wine was slightly less cold stable and required slightly more bentonite to become heat stable. Overall, judges were not able to distinguish the wines from each other. There were no major preference trends for the wines. No strong sensory differences were present as well, except that cold settling may lower the perception of Body. These results suggest that flotation may be a beneficial technique not only to reduce turn-around time, enhance juice yield, and reduce chiller load; but that it may also serve as a mechanism for preserving aromatic intensity and fruit intensity similar to cold settling.
This study examines the use of Lafazym Arom (Laffort) (pectinase and β-glucosidase) additions on the varietal character of Sauvignon blanc wines. Many volatile aroma compounds are glycosylated, resulting in very high solubility and low volatility. Thus, these compounds must be enzymatically cleaved to remove the glucose moiety in order for these aromatic compounds to be sensed. Lafazym Arom is an enzyme which may be able to impact the sensorial attributes of certain grape varieties, particularly terpenic varieties. Sauvignon blanc was harvested, destemmed, and cold soaked for 20 hours, after which grapes were pressed and settled with CinnFree for one day. Juice was racked into stainless steel barrels for fermentation and inoculated with Vin-2000. Different barrels received different rates of addition of Lafazym Arom after fermentation: 1) no Lafazym, 2) 2/ghL (low rate) Lafazym, and 3) 4g/hL (high rate) Lafazym. Barrels were then topped with sulfur dioxide. All other treatments between wines were equal. No differences in wine chemistry are apparent between treatments. Enzyme addition increased 3-mercaptohexanol, perhaps with diminishing returns at larger doses. Overall, wines produced with Lafazym Arom tended to have higher Overall Aromatic Intensity and Thiol Character. Tropical Fruit character also was generally increased with Lafazym Arom. Wines made with Lafazym Arom tended to be more preferred, although differences were present with regard to the rate of Lafazym addition. These results suggest that Lafazym Arom can have a large impact on the aromatic qualities of Sauvignon blanc.
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.
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.
This study examines the impact of racking and returning during aging on red wine quality. Petit Verdot wine was split into two identical barrels. Once malolactic conversion was completed, one barrel was racked into tank, the barrel was pressure washed and ozonated, and then the wine was returned to the barrel and topped. The other barrel had no treatment. All other treatments between wines were identical. No major chemical differences were apparent between treatments. VA was slightly lower in the racked wine. Some sulfide parameters were lower in the racked wine, although whether these differences would impact flavor is hard to say. For the triangle test, of 20 people who answered, 7 people chose the correct wine (35%), suggesting that these wines were not significantly different. In general, of those who correctly identified the wines, 2 had no preference, 2 preferred the control, and 3 preferred the rack and returned wine. For the descriptive analysis, there were no trends for the descriptors used in this study. Judges commented that these wines were very extracted, which may have masked differences between wines. In the future, this study should be repeated on less intense grape varieties. Furthermore, the wine should be allowed to age more in future studies.
This study examines impact of stirring the lees of barrel aging red wines. Cabernet Franc wine was settled overnight in tank after pressing and then racked into two identical neutral barrels. Barrel stirring occurred once malolactic fermentation completed and continued once every two weeks until wine was sampled in late April. No major differences were found in wine chemistry. Some lactic acid bacteria counts were higher, and Brettanomyces and Saccharomyces was higher in the stirred wines as well. No differences were apparent in phenolics, except for an increase in tannin in the stirred wine. For the triangle test, of 21 people who answered, 7 people chose the correct wine (33%), suggesting that the wines were not significantly different. In general, of those who correctly distinguished the wines, 3 had no preference, 2 preferred the stirred wine, and 1 preferred the no stirring wine. For the descriptive analysis, there were no strong trends for the descriptors used in this study. There was a very slight trend for the stirred wine to have lower Astringency. In the future, more studies should be performed with red wine lees stirring, perhaps with differing levels of lees in the wines as well.
Different trellising systems can have a large impact on canopy sun exposure, leaf area:fruit ratios, and yields. Different trellising systems also have different labor requirements for proper management. Determining which trellising system is best for a given site, on a given variety, is therefore very important. This study examines the difference between two training methods – VSP and Scott Henry – on resulting juice and wine quality. Merlot (clone 181) was planted in 2000 and trained as Scott Henry. In 2017, every other row of this block was converted to VSP. All vineyard treatments were identical, with leaf pulling on east side of vine after fruit set. Grapes were harvested on the same day, and all fermentation practices were identical between treatments. There were not many differences in juice and wine chemistry, except for slightly lower tartaric acid in the Scott Henry wine and decreased acidity. Tannin may have been slightly lower in the Scott Henry wine as well. Overall, these wines were not found to be significantly different, but perhaps would have been at more lenient p levels. Descriptive analysis was not completely consistent between tastings. Preferences slightly favored the VSP trellis, but this was not strong. This study should be repeated over multiple years on different grape varieties. More careful attention should be paid to viticultural parameters, such as leaf area to fruit weight ratios, and yield parameters.
This study examines the impact of different leaf pulling regimes on ripening in Cabernet Franc. Grapes received either: 1) No leaf pulling, 2) Standard leaf pulling (leaf pulling before mid-June on East side of vine), 3) pre-bloom leaf pulling (May 17, both sides of vine), 4) post fruit-set leaf pulling (June 2, both sides of vine), 5) Mechanical leaf pulling (May 26, post fruit-set, both sides of vine), 6) bagged clusters (July 22). Grapes were harvested on the same day. All other treatments were identical. Mechanical Leaf Pulling and Post-Fruit Set Leaf Pulling had the smallest average berry weight (no data is available for the bagged clusters). Pre-bloom leaf removal saw the greatest increase in average berry weight, but this was not significant when compared with No Leaf Pulling and Post-Fruit Set. Yield per vine was significantly lower on the pre-bloom leaf removal compared to No Leaf Pulling and Post-Fruit Set, but Brix was significantly higher. This yield difference likely resulted from the significantly lower cluster weight in the Pre-Bloom treatment, as well as the lower number of berries per cluster and the lower number of clusters per vine found in the leaf pulling treatments. The Pre-Bloom and Post-Fruit Set treatments spent much more time at critical temperatures between 35-40°C than the No Leaf Pulling treatment, due to greater exposure of the grapes. The Pre-Bloom treatment was overall cooler than the Post-Fruit Set treatment, possibly because of the decreased berries per cluster and thus looser cluster architecture allowing for better air flow and cooling.
Leaf pulling always increased tannin, quercetin, and anthocyanin concentration in grapes, with the greatest concentration of tannin in the Pre-bloom Leaf Removal and anthocyanin and quercetin in the Post-Fruit Set Leaf Removal. Leaf-pulled juice tended to have less malic acid and lower YAN. In general, TA and color was higher in finished wine with leaf pulling, with the greatest increases seen in post-fruit set leaf pulling. Caftaric acid, gallic acid, quercetin, tannin, and anthocyanin were generally increased by leaf pulling, with the most profound differences found in pre-bloom and post-fruit set leaf pulling. Bagged clusters showed much lower color and tartaric acid.
Due to the complexity of this project, the Mechanical Leaf Pulling and Bagged treatments were not tasted. Overall, descriptive results for these wines were inconsistent between tastings. Wines which had received leaf pulling were generally more preferred by judges, with preferences generally being for early leaf pulling regimes. This study should be repeated several times in order to further validate these results. It should also be performed on different grape varieties, at different sites, and on different trellising systems. More rigorous descriptive work should be performed on these projects, as well.
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).
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.
This study examines the impact of canopy height and ripening on wine quality in Merlot. Three sets of five rows of Merlot were hedged to different heights in mid-June: 52 inches (High canopy), 44 Inches (Medium canopy, normal height), and 36 inches (Short canopy). All other vineyard treatments were identical. Not much additional shoot growth occurred after hedging. Grapes were harvested on August 25 and processed into separate T Bins. All other treatments were identical. Juice Brix was slightly higher for the short canopy compared to the higher canopy. This may have been due to a seeming resistance to rain dilution seen in the short canopy vine compared to the medium and higher canopy vines. The ethanol, TA, color, and tannin increased with decrease in canopy height, and pH decreased with canopy height. Overall, descriptive analysis had difficulty distinguishing the wines consistently. The short canopy treatment tended to have slightly more Bitterness and Overall Aromatic Intensity. The short canopy wine also exhibited some slight reduction relative to the other two wines, which may have influenced results. Fruit Intensity and Astringency tended to vary between wines between tastings. In general, the high canopy wine tended to be the most preferred. Future studies should examine how bud fruitfulness and yield are impacted by multiple vintages of heavy hedging, pick fruit at different times depending on which treatment is deemed “optimally” ripe, and hedging shoots when they reach their designated height to try to force lateral growth. More studies are needed to confirm the trends seen in this study, as well.
This study examines the impact of bagging grape clusters during the growing season on grape and wine flavor, chemistry, microbiology, and phenolics. The vineyard uses organic grape growing practices, and the goal of this project was to see if bagging grape clusters would improve disease resistance without negatively impacting grape and wine quality. The bags used were 19x27cm white paper bags with micropores. Corot Noir grapes in one block experienced 4 treatments: 1) not bagged, 2) bagged at pea-sized berries, 3) bagged at berry touch, and 4) bagged at veraison. Because of a prediction of reduced disease incidence in bagged clusters relative to unbagged clusters, and because unbagged, rotting clusters were going to be dropped during the season, green harvesting of the treatment clusters was undertaken on lagging blooming clusters at berry set in order to attempt to keep crop levels similar between treatments. Lagging clusters were also not bagged on treatment rows. Control and treatment grapes were harvested 2 days apart from each other, and the 3 treatments were combined into one must to ferment. Both control and treatment musts received a 10% saignee, both were inoculated with Renaissance Ossia yeast, and all other treatments between wines were equal. Both bins received 2 weeks extended maceration. Bagging clusters might have reduced incidence of black rot, with the earlier bagging treatments being more effective; however, more intensive work is needed to confirm this. The grape treatments generally exhibited slight increases in berry weight and cluster weight, as well as increases in malic acid, pH, and YAN. Juice and wine chemistry was not much impacted, except that acidity was lowered in the bagged treatment. Bagging clusters lowered the microbial content of the juice, although wine was not much impacted. All phenolic and color parameters, in grape and wine, were either reduced or did not change as a result of bagging. 64% of people were able to distinguish the wines in triangle testing, suggesting a statistically significant difference between them (p<0.001). Of those who correctly distinguished between the wines, there was not a major preference for one wine over the other, perhaps slightly favoring no bags. There were strong trends for the unbagged treatments to have higher Overall Aromatic Intensity and higher Acidity. There was a slight tendency for Fruit Intensity to be higher in the unbagged treatments as well.