Vineyard Sprays to Improve Ripening in Merlot (in collaboration with VT) (2017)

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.

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Fermenting Merlot in T Bins vs Tanks (2017)

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.

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The Impact of Trellising on Ripening and Quality in Merlot (2017)

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.

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The Effect of Canopy Area on Ripening and Wine Quality (2017)

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.

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The Impact of Saignee on Wine Quality (2017)

This study examines the impact of saignee on Merlot wine quality. Merlot grapes were harvested from the same block on the same day and was split into 4 T Bins. The T Bins received the following treatments: 1) 0% Saignee, 2) 7% Saignee, 3) 15% Saignee, and 4) 25% Saignee. All other treatments between wines were identical. Brix and pH slightly increased by saignee, and TA slightly decreased in the must. Wine chemistry was not much affected by saignee. Color intensity increased with increasing saignee. Anthocyanin and tannin were also increased by saignee. These increases were generally correlated to increasing levels of saignee. Overall, the higher rates of saignee may have slightly increased Fruit Intensity, Herbaceous/Green character, Bitterness, and Astringency. The higher rates of saignee tended to be more preferred (although preferences changed between tastings). Saignee may prove to be a valuable tool in Virginia red winemaking and should be examined at many different sites among many different varieties.

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Managing Rose Thiol Character with Fermentation Temperature (2017)

This study examined the impact of increasing fermentation temperature on the chemical, sensory, and thiol attributes of Merlot rose. Merlot grapes were harvested, destemmed, and cold soaked for 1 day, then pressed off into tank. Juice was stabulated in tank for 3-5 days before racking into two separate tanks. The NTU of the juice was adjusted to 200 prior to fermentation. All treatments between the juices and wines were equal, except that the control was fermented at 14°C for the whole fermentation whereas the treatment was fermented at 20°C for the first 4 days, then dropped to 14°C for the rest of fermentation. Wine chemistry was not much affected by the treatments. Hydrogen sulfide and 3-MH were slightly lower in the higher temperature fermentation. 71% of judges were able to distinguish the wines in triangle testing, suggesting a statistically significant difference between the wines (p<0.001). This may have been due to turbidity differences from lees being disrupted in the bottles during pouring. In general, the control wine was preferred. There were no strong trends for the descriptors used in this study. There was a slight tendency for Fruit Intensity, Thiol Aromas, and Overall Aromatic Intensity to be increased by Low Temperature. The High Temperature wine may have had slight reduction relative to the low temperature wine.

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Yeast Strain Selection to Produce Sulfur Dioxide-Free Merlot Wine (2017)

This study examines the efficacy of non-Saccharomyces yeast selection to produce wines without the use of sulfur dioxide. Merlot grapes were harvested on September 28 and stored overnight at 45°F. The next day fruit was destemmed, sorted, and crushed into two separate bins (0.5 tons per treatment). One bin received 6g/hL sulfur dioxide (control), and the other received 5g/hL Primaflora VR Bio (AEB) as a sulfur dioxide replacement (no sulfur dioxide treatment). Both bins received a two day cold soak (one punchdown per day, with dry ice additions), and then the control bin received 15g/hL FX10, and the treatment received 15g/hL FX10. At this point the bins were moved out of the cold room in order to warm up. Punchdowns were twice per day until fermentation became vigorous (October 6), which then received 3 punchdowns per day. Fermentation lasted for 8 days, after which the wine was drained off the skins and put into stainless steel tanks for aging (only free run was used). On November 30, wines were filtered with K250/EK filters and sterile filtered (0.45 micron) and bottled on December 7. At bottling, the control received 1g/hL sulfur dioxide. The wine without sulfur dioxide had slightly less alcohol and lactic acid, and slightly increased volatile acidity. It also had less color and had a slightly longer lag phase in fermentation. The no sulfur dioxide wine seemed to have more yeasts throughout its life except for Hanseniaspora, relative to the control. Both fermentations had similar bacterial counts. Overall, judges were more or less able to correctly distinguish the wines made with and without sulfur dioxide, although in one tasting this was statistically significant and at the other it was not. Judges tended to prefer the wine made without sulfur dioxide. The no sulfur wine may have had higher Fruit Intensity, higher Overall Aromatic Intensity, and higher perceived Acidity relative to the wine made with sulfur dioxide.

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Carbonic Maceration in Merlot (2017)

This study examines the difference in aroma, flavor, and mouthfeel produced from fermenting Merlot traditionally versus through carbonic maceration. Merlot grapes were harvested on September 27, and some was split into a macrobin while the rest was added whole cluster to a carbon dioxide-flushed stainless steel tank. The carbonic maceration treatment tank was flushed with carbon dioxide twice per day, and the tank was not opened for 7 days. After 7 days, the carbonic maceration whole clusters were removed, and destemmed into a T bin, where it also received a more traditional fermentation. Musts in T Bins received 2 punchdowns per day. Both T Bins (the traditional and the carbonic maceration one) were pressed off on the same day (October 19). All other treatments between wines were equal. The carbonic maceration wine had lower ethanol, higher TA, and higher succinic acid. Most higher alcohols and esters were higher in the carbonic maceration wine. Color and phenolics were lower in the carbonic maceration wine. There was a significant sensory difference between the carbonic maceration and traditional fermentation wines (p<0.001), with a slight preference for the carbonic maceration wine. These results suggest that carbonic maceration reduces Astringency and increases Ester Intensity and Overall Aromatic Intensity.

 

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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 Different Cap Management Techniques on Merlot Wine (2016)

This study examines the effect of different cap management techniques on the chemical and sensory qualities of Merlot wine. Merlot grapes were harvested on the same day and split into 3 separate 1-ton T bins with three different treatments: 2 punchdowns per day, 4 punchdowns per day, and 2 pumpovers per day. The timing between 2 punchdowns and pumpovers were approximately 5-8 hours apart, and the timing between 4 punchdowns was approximately 1-2 hours apart. Increasing punchdowns and pumpovers increased the pH (5% and 22% lower proton concentration, respectively) and pumpovers slightly decreased TA. The treatments also increased the volatile acidity and increased the sulfur dioxide binding capacity of the wine. Increasing the number of punchdowns had the greatest impact on color, catechin, and tannin accumulation, although pumpovers slightly increased this as well. Anthocyanins were decreased by the treatments, especially with the 4 punchdown treatment. Overall, these wines were not perceived to be very different from each other. The 2 Punchdown wine seemed to be slightly more preferred than the rest of the treatments, but this was a weak preference. Descriptive analysis from both tastings suggest that the 2 Punchdown wine may have been slightly lower in Astringency, Bitterness, Body, and Herbaceous/Green character. However, if so then this was a very weak trend.

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The Effect of Tannin and Oak Addition on Merlot (2016)

This study examines the impact of adding either VR Supra (Laffort) or both VR Supra and untoasted oak chips on the sensory and chemical qualities of Merlot. Merlot was harvested on the same day from the same block and processed identically into three separate T Bins, one of which was a control, one of which received VR Supra, and one of which received both VR Supra and untoasted French oak chips. All other treatments were the same between groups.  No major differences could be seen in wine chemistry. Color was not impacted much, but the treatments lowered anthocyanins. Adding tannin and adding oak chips increased tannin. The differences between treatments, however, were not that great. Overall, conflicting results were found for the two tastings this project was poured at. At the Shenandoah tasting (May 3), most judges preferred the wine with both Oak Chips and VR Supra, whereas on May 17 that was the least preferred. Oak chips with VR Supra tended to increase Astringency and Bitterness, but this was a weak tendency. These results suggest that these wines could be tailored to meet the demands of different consumer groups. However, the number of judges in these studies were small, and in the future more work should be done on these wines. Additionally, this wine was unusually high in alcohol and extraction due to the vintage, and more of a difference with these treatments may be more observable in different vintages.

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Effects of Adding Hydrolyzable vs Condensed Tannin during Red Wine Fermentation (2016)

This study examines the impact of adding different sources of exogenous tannin to fermenters during Merlot processing. The treatments were set up as follows: 1) Control, 2) FT Rouge (ScottLabs) at 30g/hL, 3) FT Rouge (ScottLabs) at 50g/hL, 4) Tanéthyl Effe (AEB) at 10g/hL, and 5) Oenotan Selection (Esvin) at 10g/hL. All treatments were the same, except that the treatment with FT Rouge at 50g/hL was inoculated with a different yeast from the rest. This wine was therefore not tasted at sensory sessions. No major wine differences could be seen between treatments. The tannin varied with their effect on color intensity: some increased intensity slightly whereas others slightly decreased it. Anthocyanin, in general, was slightly lowered by tannin addition. Tannin content was relatively unaffected, except for FT Rouge 50, which experienced a large increase in tannin. The differences from FT Rouge 50, however, may have been due to the yeast strain used, and does not indicate necessarily that the increase in tannin addition had the effects. Overall, no major preferences could be seen for any treatment, except that the Tan Ethyl Effe was often least preferred. There may have been large changes in wine sensory qualities in bottle over time, as the wines seemed to taste different at the different tastings. This could confound any attempt to compare wines across tastings. This study suggests that exogenous tannin can have impacts on final wine chemistry and sensory qualities, and this may be largely impacted by yeast strain selection as well. In the future, more studies examining the combined impact of exogenous tannin addition with yeast strain selection should be performed.

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Whole Cluster Inclusion in Merlot Fermentations (2016)

This study examines the impact of whole cluster inclusion on the sensory and chemical profile of Merlot. Merlot was harvested from the same vineyard block on the same day and processed identically except that one treatment was only 70% destemmed (not crushed) with the other 30% of fruit added as whole clusters. All other treatments were the same. Whole cluster inclusion did not affect wine chemistry, except for slightly increasing pH. Whole cluster inclusion lowered color intensity, anthocyanin content, quercetin, caftaric acid, and epicatechin. However, tannin and catechin content was slightly increased by whole cluster inclusion. Hue was also increased, due to the lower absorbance at 520. Judges found the wines to be significantly different (p<0.01), but no real preference trends could be seen between treatments. 30% whole cluster inclusion tended to score slightly higher in all attributes except for Fruit Intensity and Astringency, where it was the same as 0% whole cluster inclusion. However, the differences for these descriptors were very small, and more studies are needed to identify in what ways the wines can be described as different.

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The Effect of Stabulation on Fermentation Kinetics and Sensory Quality (ARC) (2016)

This study examines the effect of different rosé must processing techniques on the chemical and sensory qualities of finished wine. Merlot grapes were either sent directly to press or cold soaked for two days prior to pressing. After cold soak and pressing, juice was either settled and inoculated or stabulated for approximately 5 days, after which it was inoculated and a Laffort thiolase enzyme was added. Merlot sent directly to press underwent stabulation. Not many chemical differences could be seen between stabulated juices with the control, except a higher initial turbidity. These results suggest that for this particular style of rose winemaking, judges preferred wine made from the two-day cold soak, regardless of stabulation. Although the stabulated and control wines were found to be significantly different, no major trends could be seen for the descriptors used in this study except for perhaps a slight increase in fruit intensity and thiol aromas. No major preference could be seen for the control wine and stabulated wine, suggesting that stabulation can act as a technique to process wine without much altering the flavor profile in a negative matter.

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The Effect of Crop Adjustment and Desiccation Spray on Ripeness (2016)

This study examines the impact of different crop adjustment techniques on yield, juice and wine chemistry, phenolic and color profiles, and sensory characteristics of Merlot. The four treatments in this trial were performed in the same vineyard block as follows: two control rows, two rows sprayed with RG 1950 desiccant spray, two rows with clusters dropped at veraison down to one cluster per shoot, and two rows with clusters pinched at approximately 20 Brix. All other treatments, through vinification, were the same. The desiccation spray exhibited faster ripening kinetics and lower average berry weight. At harvest, Brix and pH were not very different, but TA was higher in the treatments. No differences were apparent in wine chemistry. All treatments exhibited increases in color intensity, especially the cluster dropped treatment. In spite of increasing color intensity all treatments lowered anthocyanins. The desiccant treatment slightly increased tannins. The week before harvest, 6 inches of rain fell, which may have reduced the impact of these treatments. Overall, desiccation and crop reduction had a slight tendency to enhance Fruit Intensity. The treatments also tended to enhance Overall Aromatic Intensity. These trends were weak and often conflicted between tastings. There seemed to be a general preference for wines produced from dropped clusters and desiccated clusters, but this varied. The rain event may have reduced the impact of these treatments. This study suggests that crop adjustment techniques have the potential to impact fruit and wine quality in Virginia, but much more studies are needed to fully quantify this impact as well as to account for vintage variation.

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Color and Tannin Extraction and Stabilization in Red Winemaking (ARC) (2016)

This study examines the impact of different tannin addition practices on the color and tannin profiles of Merlot wine. Merlot was harvested from the same block and split into three separate fermentation vessels. One vessel received no tannin or oak chip additions, a second vessel received VR Supra and Lafase HE Grand Cru at processing, and VR Color during fermentation (ARC-Laffort Protocol), and a third treatment received Lafase HE Grand Cru and mini chips bois frais oak chips at processing. All other treatments between wines were equal. Wine chemistry between treatments were the same, except that the control tended to have slightly lower TA. Both treatments increased color intensity and tannin, with the Laffort-ARC protocol having the greatest impact. The treatments slightly increased catechin and gallic acid. The treatments tended to slightly lower anthocyanins, but increased polymeric pigment. No strong trends could be seen for the descriptors used in this study. There was a slight tendency for the control to have higher Fruit Intensity and lower Astringency. The Oak Chips + Grand Cru had a slight tendency to increase Body, Bitterness, and Overall Aromatic Intensity. However, these were weak trends. In general, the ARC-Laffort Protocol Treatment was the least preferred. Several judges described these wines as having slightly oxidized characteristics, and as such these sensory results may not be very representative. 

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The Effect of Enzyme, Cap Management, and Tannin on Phenolics in Merlot (2016)

This study examined the impact of 5 winemaking techniques on the phenolic composition of Merlot. The treatments were as follows: 1) Control, 2) Stomping grapes during a delestage (otherwise identical to control), 3) Lafase Grand Cru (Laffort) at crush, 4) VR Supra (Laffort) at crush, and 5) Both Lafase Grand Cru and VR Supra at crush. All other treatments were the same between wines. All wines had a delestage operation performed at 2 Brix, where stomping occurred for the stomping treatment. There were no major chemical differences between wines. Stomping had very little effect on phenolic chemistry. VR Supra and Grand Cru alone increased color, but when combined color was lowered (corresponding to lower anthocyanins). No other impacts on phenolic qualities could be observed, except tannin was increased and gallic acid decreased in the wine treated with VR Supra. The sensory impact of the VR supra treatment cannot be adequately assessed due to it being an outlier. Overall, the treatments tended to slightly increase Fruit Intensity and Body relative to the Control. The stomped wine tended to be the most preferred wines for all but the May 3 Tasting. Grand Cru + VR Supra also tended to be regarded fairly highly. The Control wine tended to be the least preferred. These results were not very strong, however, and more studies on the impacts of these treatments on the chemical and sensory qualities of wine should be performed. Additionally, more work should be done to examine the impact of these treatments on wine during aging.

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Carbonic Maceration vs Traditional Fermentation in Merlot (2016)

This study examined the impact of carbonic maceration on the chemical and sensory qualities of Merlot in comparison to traditional fermentation. Carbonic maceration lowered all phenolic and color attributes in the wine. Most wine chemical parameters stayed the same, except that lactic acid was greatly increased in carbonic maceration. These results suggest that carbonic maceration reduces Body and Astringency compared to traditional fermentation. These results also suggest that the aroma in carbonic maceration changes greatly over a short period of time, as the Fruit Intensity and Ester Intensity of the carbonic maceration tended to more approach that of the traditional fermentation over time. Tasting order had a very large impact on descriptive analysis, so much of these results should be interpreted with care. Because the carbonic maceration wine is intended to be used as a blending component in red winemaking at this winery, in the future blending trials should be performed. Additionally, different carbonic maceration techniques should be employed, such as altering the temperature and time of carbonic maceration, or destemming berries at processing prior to maceration.

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Sulfur Dioxide-Free Winemaking with Merlot (2015)

Merlot was produced using traditional winemaking practices and sulfur dioxide-free winemaking practices.  There were very little chemical differences between the control and low sulfur dioxide treatments.  The traditional method seemed to have a higher microbial presence.  The traditional method seemed to result in higher phenolic extraction (probably due to increased extraction from sulfur dioxide), but higher color intensity was found in the sulfur dioxide-free wine.  This is likely due to less monomeric anthocyanin bleaching.  There was no significant sensory difference (p<0.05) between the traditional and sulfur dioxide-free wine. However, of those that responded correctly (n=13) 69% preferred the control and 31% preferred the trial.

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