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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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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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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Clonal Assessment of Cabernet Franc (2017)

This study examines the clonal differences between Cabernet Franc clones 214 and 327. Grapes were harvested separately on October 4, 2017. Must was inoculated with ES488 and was pressed off after around 18-19 days of maceration. Both wines received the same additions, and all other treatments were identical between wines. Clone 327 tended to have higher berry weight and cluster weight, although yield was slightly lower. Grape chemistry suggests that clone 214 had lower tannin and phenolics, but slightly higher anthocyanins. Juice and wine chemistry did not differ too much. Clone 214 wine tended to have slightly higher phenolic parameters, although these differences were weak. It is possible, then, that although Clone 214 had lower levels of phenolic compounds (except anthocyanin), phenolic compounds were more extractable from these grapes. However, Clone 214 received an addition of Lafase HE Grand Cru which Clone 327 may not have received, and this may have impacted the results as well. Overall, the wines were not found to be significantly different via triangle testing. Descriptive analysis did not yield any consistent trends between tastings. There may have been a slight preference for Clone 327, but this was weak. More work should focus on the sensory and chemical differences between wines produced from these clones, but more work should also be done to better distinguish viticultural characteristics between these wines, as well.

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No Sulfur Winemaking in Chardonnay (2017)

This study examines the effect of fermenting wine with and without sulfur dioxide. Chardonnay grapes were harvested and pressed into 3 separate tanks. At pressing, one treatment received 3g/hL sulfur dioxide (control), and the other did not receive any sulfur dioxide, and the third did not receive any sulfur dioxide and received Stab Micro M and Tan Blanc at pressing and followed an Enartis no sulfur winemaking protocol. After settling, the juices were racked into barrel and inoculated with CY 3079. The Enartis wine received additions of Claril SP during settling. After completion of malolactic conversion, the control wine was stabilized with sulfur dioxide, and the Enartis treatment had Stab SLI, Tan SLI, and Stab Micro added at the end of malolactic conversion. Both barrels with the Enartis treatment fermented slower than the rest. No major chemistry differences were found between wines except for slightly lower lactic acid in the Enartis wine. The no sulfur wine had slightly higher levels of Lactic Acid Bacteria, slightly less O. oeni, and slightly less S. cerevisiae. The Enartis wine had slightly more S. cerevisiae, and slightly higher diacetyl. In general, judges were able to distinguish between the wine made with and without sulfur dioxide. This may have been due to a perceptible difference in diacetyl between these two wines, likely due to diacetyl binding by sulfur dioxide in the wine produced with sulfur dioxide. The no sulfur wine treatment may have had slight oxidation (but not in a negative respect), and the Enartis no sulfur wine may have had a slight bitterness (although this was not examined statistically). A perceived bitterness in the Enartis wine may be due to the use of sacrificial tannin. Preferences were not strong, but there seemed to be a preference for the wine made with sulfur dioxide, and then perhaps followed by the wine made without sulfur dioxide. However, many more studies are needed to further qualify how no sulfur winemaking impacts wine sensory qualities. Additionally, more studies need to be performed to determine how no sulfur wines age over time.

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No Sulfur Winemaking in Cabernet Franc (2017)

This study examines the effect of producing wine with and without sulfur dioxide. Cabernet Franc grapes were harvested and processed into 3 separate T Bins. During crush, one treatment received 25ppm sulfur dioxide (control), the second did not receive any sulfur dioxide but instead was protected at crush with Zymaflore Egide, and the third did not receive any sulfur dioxide but instead received Tan Rouge and Stab Micro M during crushing and followed an Enartis no sulfur winemaking protocol. After processing, all wines were inoculated with ES488. One-third through fermentation the Enartis treatment received additions of Pro Tinto and Tan Color. Both no sulfur treatments were inoculated with ML Silver after pressing. At the end of fermentation, the control wine was stabilized with sulfur dioxide, the no sulfur wine received Stab Micro, and the Enartis protocol received additions of Surli Round, Tan SLI, and Stab Micro M. Wine chemistry is similar between treatments, except that no sulfur winemaking resulted in slightly lower TA. Both no sulfur winemaking wines had higher levels of acetic acid bacteria, lactic acid bacteria, and Pediococcus. Color intensity was higher due to a lack of sulfite bleaching. Overall, Cabernet Franc produced with sulfur dioxide tended to have higher perceived Acidity. Other differences between wines were not easy to distinguish with the descriptors used in this study, but the no sulfur wine and the wine with sulfur dioxide may have had slightly higher Overall Aromatic Intensity and Fruit Intensity. The wine made with sulfur dioxide tended to be most preferred, followed by the wine without sulfur dioxide. Conclusions are difficult to draw at this point. Many more studies are needed on no sulfur winemaking in red wines and its impact on sensory qualities. Additionally, more studies are needed to examine how aging is affected by no sulfur winemaking.

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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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Whole Cluster Inclusion in Cabernet Franc Fermentations (2016)

This study examines the impact of whole cluster/stem inclusion on the sensory and chemical profile of Cabernet Franc. Cabernet Franc was harvested from the same vineyard block on the same day and processed identically except that stem inclusion was performed so that either 100% of the fruit was destemmed but not crushed, 60% of the fruit was destemmed but not crushed (40% added as whole clusters), or 10% of the fruit was both destemmed and crushed and the other 90% was added as whole clusters. All other treatments were the same. The 40% Inclusion treatment was not tasted. Whole cluster inclusion did not affect wine chemistry. Color intensity and hue were both increased at 40% and 90% whole cluster inclusion. Cinnamic acids, catechin, tannin, and polymeric anthocyanins were also increased with 40% and 90% inclusion (although polymeric anthocyanins were not very different). Epicatechin and anthocyanins were lowered by 40% and 90% whole cluster inclusion. The results for 40% inclusion were taken at different time points, however, so may not be entirely representative. Judges found the wines to be significantly different, but there were no strong preferences for one treatment over another. 90% inclusion had a slight tendency to have higher Overall Aromatic Intensity and Fruit Intensity, but this was not seen at all tastings. More studies should be performed on whole cluster and stem inclusion to determine how to best vinify different treatments. This is especially true with regard to microbial stability, as well as finding optimal ranges of cluster/stem inclusion based on desired styles.

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ScottLabs IONYS WF Yeast Trial on Chardonnay (2016)

This study examines the impact of IONYSWF yeast (Lallemand) on Chardonnay wine when compared to fermentation with CY3079. Chardonnay juice was settled and split into separate barrels, inoculated with either CY3079 or IONYSWF. Although the IONYSWF fermentation proceeded much slower, not many chemical differences could be seen between the different yeast strains, except that the pH and TA of the IONYSWF – fermented wine was slightly higher. The lower level of free sulfur dioxide in CY3079 suggests a slightly higher production of sulfur dioxide-binding compounds. These results suggest that people are able to tell a difference between Chardonnay wine produced with IONYSWF yeast and wine produced from CY3079. People often preferred wine produced with IONYSWF yeast, likely due to its tendency to enhance Fruit Intensity, Overall Aromatic Intensity, Depth of Flavor, and Body. Although the yeast is marketed to increase acidity, this was not observed in this study. This yeast shows promise with regard to aromatic development in Chardonnay, but more studies are needed to confirm this.

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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 Bactiless on Microbial Stability in Petit Verdot (2016)

This study examines the impact of Bactiless (ScottLabs) on the chemical, microbial, and sensory profiles of two Petit Verdot wines, one of which was not tasted. Petit Verdot wine was racked into two separate barrels for each wine, and allowed to undergo natural malolactic conversion. After malolactic conversion, one barrel from each wine received a sulfur dioxide addition of 6.6g/hL, whereas the other barrel from each wine received 4.4g/hL sulfur dioxide and 50g/hL Bactiless. After 10 days both barrels were racked and returned. Bactiless seemed to lower cell counts for Pediococcus sp, acetic acid bacteria, and Oenococcus oeni. The results varied between wines, however. Other microbes were not strongly impacted by the treatment, but in many cases the cell count may have been too low to be impacted by the treatment. The wines were not significantly different from triangle testing. No major descriptive trends could be seen in this study.

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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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Yeast Nutrient Comparison in Chardonnay (2015)

The effects of the yeast nutrients Go Ferm, Fermaid O, and Fermoplus DAP Free on fermentation kinetics, wine chemistry, wine microbiology, and wine sensory attributes, were compared .  Go Ferm resulted in the most rapid fermentation.  Not much chemical differences were observed.  Most people preferred the wine made with Fermoplus DAP Free.

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Andante, D254, and IONYS WF Yeast Trial in Petit Verdot (2015)

Andante, D254, and IONYS WF yeast strains were used in the fermentation of Petit Verdot.  IONYS WF yeast seemed to increase the titratable acidity and lower the pH slightly, and also seemed to lower the overall phenolic content of the wine.  IONYS WF and D254 wines were slightly more preferred than Andante wines.

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