Using Yeast to Improve Color and Aroma Extraction from Skins (in Collaboration with 2B) (2017)

This study examines the impact of Rubino Extra (2B), BM45 (ScottLabs), and Alchemy III (Anchor) on the phenolic and aroma characteristics of Cabernet Franc wines. The goal was to see if the Rubino Extra yeast could enhance anthocyanin and aroma extraction from the grapes, relative to other yeast strains. Grapes were harvested on the same day and processed into 3 separate T Bins. Each of the three T Bins were inoculated with one of the three yeasts. All other treatments between wines were identical. The BM45 trial fermented slowest, and Rubino Extra trial fermented fastest. Lactic acid was higher in the wine produced with BM45. Color intensity varied among yeasts. Anthocyanins were higher in the Alchemy 3 trial, and lower in the Rubino Extra trial. Overall, not many trends were seen between these wines. The Rubino Extra yeast tended to produce wines with slightly lower Overall Aromatic Intensity and Fruit Intensity. The Alchemy 3 and BM45 yeasts were fairly similar, except that BM45 was perhaps more in-between the Rubino Extra and the Alchemy 3 yeast. The Alchemy 3 yeast appeared to produce a distinctive floral or fruity quality. Preference trends reversed between tastings, and as such it is unclear which yeast strain was the most preferred.

Read Full Report (PDF)

The Impact of Yeast Fining on Wine Quality Prior to Bottling (Enartis, Laffort) (2017)

This study examines the impact of different yeast fining techniques on finished wine quality. A 2017 red wine blend (75% Cabernet Franc, 25% Petit Verdot) was blended into tank in early February. Then, on February 8 the wine was split into four analogous neutral barrels, and the barrels either received no treatment (control), a BM45 yeast addition at 1g/L, a Surli Velvet (Enartis) addition at 0.05g/L, or an Oenolees (Laffort) addition at 0.4g/L. The barrels were stirred on the date of addition and a week later. The wine was pulled for analysis and bottle samples on March 15. There were no differences in wine chemistry and color. For the descriptive analysis, there were no strong trends for the descriptors used in this study. There was a slight tendency for the BM45 treatment to have higher Fruit Intensity, Overall Aromatic Intensity, and Body and lower Herbaceous/Green character. Oenolees had a slight tendency for lower Fruit Intensity and Bitterness. Surli Velvet had a slight tendency towards higher Herbaceous/Green character and Astringency. Many of these differences were not very pronounced, however, and many judges commented that differences were slight. All wines were equally preferred, more or less. Some judges remarked that the BM45 treatment seemed to have a larger effect on the mouthfeel than the rest. More studies are needed in order to better quantify the impacts of these treatments on wine flavor and aroma quality.

Read Full Report (PDF)

The Impact of Soil Conductivity on Petit Verdot Ripeness and Wine Quality in VSP Trellising (in collaboration with Bubba Beasley) (2017)

This study attempts to quantify the impact of soil conductivity on VSP-trained Petit Verdot juice and wine chemistry, as well as on the sensory qualities of wine. Soil conductivity was determined by EM mapping performed by Bubba Beasley, in order to find areas of low and high conductivity within the vineyard block. The low conductivity soil had a low rock content, and the high conductivity soil had high rock content (75%, shale). Then, fruit from each conductivity region was harvested on the same day but kept separate and destemmed into two T Bins: One for low conductivity fruit, and the other for high conductivity fruit. Fermentations were punched down twice per day, and all other treatments between wines were identical. Yield and viticultural parameters suggest an ESVC:CW index of 1.2 for both the low conductivity and high conductivity. Acidity and potassium was higher in the high conductivity juice. Indeed, soil pH was found to be negatively correlated to petiolar potassium and positively correlated to fruit pH. Petiolar potassium was also found to be positively correlated to juice potassium. Wine made from higher conductivity grapes had higher acidity and lower potassium. The high conductivity treatment had slightly lower anthocyanin and tannin measures. These results, overall, suggest that the lower conductivity wine had generally “riper” characteristics. These results would not be expected, as the higher conductivity soil (with higher rock content) would be expected to have less total available water in the soil for the grapevines to use. It would be more expected, therefore, that the high conductivity vine would have had less water, and thus potentially more “ripe” chemistry characteristics. Overall, the wines were not found to be significantly different at tastings. There may have been a slight preference for the low conductivity wine, but if so it was very weak. There were slight tendencies for the high conductivity treatment to have higher Acidity and Bitterness, and slightly lower Body. These further suggest a less “ripe” wine was produced at the high conductivity block. This study should be repeated over multiple vintages in order to determine whether these results are replicable.

This study should be read with its companion study in Ballerina trellising.

Read Full Report (PDF)

The Impact of Soil Conductivity on Petit Verdot Ripeness and Wine Quality in Ballerina Trellising (in collaboration with Bubba Beasley) (2017)

This study attempts to quantify the impact of soil conductivity on ballerina-trained Petit Verdot juice and wine chemistry, as well as on the sensory qualities of wine. Soil conductivity was determined by EM mapping performed by Bubba Beasley, in order to find areas of low and high conductivity within the vineyard block. The low conductivity soil had lower soil rock content (10%, channers), and the high conductivity soil had higher rock content (50%, shale). Then, fruit from each conductivity region was harvested on the same day but kept separate, and destemmed into two T Bins: One for low conductivity fruit, and the other for high conductivity fruit. Fermentations were punched down twice per day, and all other treatments between wines were identical. Average berry weight and cluster weight were slightly higher in the high conductivity treatments. Yield and viticultural parameters suggest an ESVC:CW of 1.7 and 1.9 for the low conductivity and high conductivity, respectively. Juice Brix and potassium was lower, and acidity and nitrogen were higher in the high conductivity treatment. These differences transferred through to wine chemistry. The high conductivity treatment seemed to have lower levels of phenolic compounds, and lower color. These results, overall, suggest that the lower conductivity wine had generally “riper” characteristics. These results would not be expected, as the higher conductivity soil (with higher rock content) would be expected to have less total available water in the soil for the grapevines to use. It would be more expected, therefore, that the high conductivity vine would have had less water, and thus potentially more “ripe” chemistry characteristics. Overall, these wines were not found to be significantly different in triangle testing. No preference trends could be seen. Additionally, descriptive analysis results were inconsistent between tastings, and no general trends can be seen except perhaps that the high conductivity wine had slightly lower Body. In the future, this study should be repeated over multiple vintages, on different grape varieties, and at different sites.

This study should be read with its companion study in VSP trellising.

Read Full Report (PDF)

The Impact of Agrothermal Systems Heat Blast Treatments on Grape Ripening, Wine Chemistry, and Wine Quality in Virginia (2017)

The aim of this experiment was to determine measurable differences of grape quality by utilizing Heat Blast technology used to treat wine grapes. A block of Petit Manseng was divided into two separate sections. One section was treated with heat blast delivery to the canopy and fruiting zones using an Agrothermal Systems XT heat system. The other section was not treated with this technology. The treatment block was treated 1 to 4 times per month depending on stage of growth, with the treatment regime starting around veraison. The majority of treatments were near veraison. Chemical spray regimes were the same between treatments. All other vineyard and winemaking treatments between grapes were equal. Acidity and potassium was slightly lower in the heat-treated grapes. Quercetin and tannin slightly increased in grapes, whereas catechin slightly decreased. Wine chemistry was not very much affected except for lower malic acid levels in the heat treatment. The tannin content of wine with heat treatment was slightly higher for most compounds. Overall, these wines were not found to be significantly different. There was a very slight tendency for the Control to have higher Tropical Fruit intensity, Fruit Intensity, and Body. No major preference trends could be seen between wines. In the future, more studies should be performed with Agrothermal heat treatment and its impacts on fruit chemistry. These studies should look into multiple grape varieties, as well as closely monitor disease progression. The use of Agrothermal heat treatment in conjunction with different vineyard spray regimes should be investigated as well. Although more studies are needed to confirm this, these preliminary results suggest that heat treatment may be a beneficial tool for East Coast viticulture.

Read Full Report (PDF)

Whole Cluster vs Stem Inclusion in Chambourcin (2017)

This study examines the impact that fermenting with whole clusters or with stem inclusion has on Chambourcin wines. Chambourcin grapes were harvested from the same block on the same day and separated into 3 T Bins. One T Bin received 100% destemmed and crushed fruit (control). The second T Bin received 30% whole clusters at the bottom, and then was filled with 70% destemmed and crushed fruit (by weight). The third T Bin received 30% of the stems by weight from the control at the bottom of the T bin, and then were filled with the same weight of destemmed and crushed grapes as the control and treatment. All other treatments between musts and wines were identical. pH was slightly increased by whole cluster and stem inclusion, and TA and tartaric acid was slightly decreased. Pyrazine was slightly increased by the treatments. Color intensity was not much affected by the treatments. Catechin, epicatechin, and quercetin were slightly increased by the treatments. Tannin was increased by the treatments, and anthocyanins were decreased by the treatments. Overall, stem inclusion seemed to result in lower Bitterness, and may have lowered Astringency and Herbaceous/Green character. The whole cluster and the control treatments tended to be higher in Herbaceous/Green character. The intensity for the descriptors for whole cluster inclusion seemed to change over time, perhaps due to ester qualities decreasing over time in bottle. Preference trends were hard to determine, although whole cluster and stem inclusion wines tended to be more preferred over the control.

Read Full Report (PDF)

The Impact of Cold Soak vs Extended Maceration in Petit Verdot Wine (2017)

This study examines the impact of cold soaking vs extended maceration on Petit Verdot wine, with maceration time being equal between treatments. The goal was to have on treatment spend more time exposed to an aqueous phase, with the other treatment having more time exposed to an alcoholic phase. Petit Verdot grapes from the same vineyard block were harvested on the same day and destemmed into two separate T Bins. One T Bin underwent a 4 day cold soak prior to inoculation, whereas the other was immediately inoculated without cold soak. Both treatments underwent a 25 day maceration before being pressed off on the same day: thus, the cold soak received less time in contact with must in an alcoholic phase. All other treatments between wines were identical. Wine chemistry and ester profiles were not much different between treatments. The extended maceration treatment had higher levels of color, epicatechin, and tannin, but other phenolic compounds were not much different. The wines were not found to be significantly different via triangle testing. However, there was a strong trend for the cold soak wine to have higher Astringency than the extended maceration wine. There was a slight tendency for this wine to have increased Bitterness and lower Body as well. The total maceration time for these wines was long in both cases, and as such the differences seen here may be greater if smaller overall maceration times are used. In the future, this should be performed, and more microbial analysis should be performed as well.

Read Full Report (PDF)

Use of CelStab on Tartrate Stability in Vidal Blanc (2017)

This study compares the effects of CelStab (Laffort) on the tartrate and colloidal stability of Vidal Blanc vs traditional cold stabilization. Vidal Blanc grapes were whole cluster pressed and fermented normally. After fermentation, samples were taken for heat and cold stability in November, and later the wine was bentonite fined and then sterile filtered into two separate vessels. One vessel received traditional cold stabilization at 28°F, and the other vessel had CelStab added at 1mL/L to induce chemical tartrate stabilization. All other treatments between wines were equal. Both treatments increased cold stability, but traditional cold stabilization had a greater impact in this case. Other wine chemistry was not affected by the treatments. Wines were not found to be significantly different via triangle test. There were no strong preference or descriptive trends between wines.

Read Full Report (PDF)

Enhancing Color Stability of Norton with Different Enological Fermentation Tannin (2017)

This study examines the impact of adding different kinds of exogenous tannin prior to fermentation in Norton grape must. Norton grapes were harvested on the same day and destemmed into four T bins. The T bins then received the following treatments: 1) No tannin addition (control), 2) Tan Color (Enartis) addition at 180g/ton followed by Pro Tinto addition (150g/ton) partway through fermentation (mostly condensed tannins), 3) FT Rouge (ScottLabs) addition at 60g/hL (hydrolysable tannin), and 4) a series of BSG product additions: UVA V-Tan at 30g/hL, Premium Limousin at 15g/hL, and Premium Color at 15g/hL (mix of condensed and hydrolysable tannins). All other treatments between wines were equal. After approximately two weeks, wine was pressed off. The BSG wine and the FT Rouge wine had slightly slower fermentations. Wines had slightly differing alcohol contents (slightly higher when using condensed tannin, and slightly lower when using hydrolysable tannin), but otherwise no major chemistry differences were seen. No color differences can be seen. The addition of these products may have slightly lowered caftaric acid and increased epicatechin and gallic acid, and these increases were more correlated to products containing condensed tannin. No major tannin or anthocyanin differences could be seen. For the descriptive analysis, there were no strong trends for the descriptors used in this study. There were slight trends for the control to have lower Fruit Intensity, Astringency, and Body. The wines made with BSG products tended to have higher Fruit Intensity, Overall Aromatic Intensity (along with FT Rouge in this regard), Bitterness, Astringency, and Body. The Pro Tinto/Tan Color and FT Rouge treatments were relatively similar and often fell in-between the Control and BSG products, except for FT Rouge with Overall Aromatic Intensity (where it was higher) and for Pro Tinto/Tan Color with Herbaceous/Green quality. In general, there was a preference for the wine produced with BSG products; however, judges thought that the wines were all fairly similar. In the future, more studies should be performed with these products on different grape varieties.

Read Full Report (PDF)

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.

 

Read Full Report (PDF)

Leaf Pulling on One vs Two Sides of Petit Verdot Vines (2017)

This study examines the impact of leaf pulling on one vs both sides of the vine in Petit Verdot. Petit Verdot vines (clone 400, planted 2012, 9x4 spacing, ESVC/CW index of 2.4) from the same block were split so that all vines received leaf pulling on the east side at flowering, and one portion of the vineyard received leaf pulling on the west side as well at veraison. Grapes were harvested on the same date, and all winemaking practices were identical between treatments. Must was inoculated with D80, Enzyme CX was added, punched down twice per day until fermentation was complete, and then switched to one punchdown per day during extended maceration (25 days maceration time, total). Juice chemistry was similar between treatments, although leaf pulling on one side resulted in higher alcohol content and lower acidity. Color and anthocyanin were not much impacted by treatments. Seed tannin indices (catechin, epicatechin, and gallic acid) may have been slightly lowered with leaf pulling on both sides. Tannin may have slightly decreased by this treatment, as well. The sensory results suggest that the two wines were significantly different. No strong trends could be seen for the descriptors used in this study,  although Acidity seemed to be lower in the one sided leaf pulling wine. No major preference trends could be seen between treatments. This study should continue to be performed over multiple years, in different regions, as well as on different grape varieties.

Read Full Report (PDF)

The Effect of Directly Processing Fruit after Harvest vs Processing after Refrigerating in Cabernet Sauvignon (2016)

This study examines the impact of directly processing fruit after harvest compared with harvesting fruit after it has been refrigerated overnight.  Cabernet Sauvignon grapes were picked from the same block on the same day and were either destemmed into T bins on the same day of harvest or refrigerated overnight before processing the next day.  All other treatments were identical.  The grapes which were refrigerated overnight exhibited slight increases in color intensity, but otherwise no major chemical differences could be found between treatments.  Overall, the wines were not found to be very different.  Very few differences could be seen with descriptive analysis.  These results suggest that refrigerating overnight prior to processing may not have any detrimental effects on finished wine quality.  However, this study should be repeated multiple times, with several different kinds of grapes as well as different levels of grape quality and cleanliness.

Read Full Report (PDF)

The Effect of Adding Tannat Skins and Exogenous Tannin to Chambourcin Fermentations (2016)

This study examines the impact that different sources of fermentation tannins will have on the sensory and phenolic qualities of Chambourcin wine. Chambourcin picked at the same time from the same block were crushed and destemmed into four fermentation bins, each with 1.5 tons of grapes. One bin was a control with no exogenous tannin added; the second bind received oak chips and fermentation tannins (Color Max and FT Rouge); the third bin received 75 pounds of Tannat skins; and the fourth bin received oak chips, fermentation tannins, and Tannat skins. All other treatments between lots were the same. In general, adding oak and tannat skins lowered color and phenolic attributes, except that tannin was slightly increased. Adding these compounds seemed to increase catechin and epicatechin. Adding Tannat skins and oak chips together increased catechin and epicatechin and slightly increased color intensity. Descriptors were mixed, and not too many differences could be seen between wines with the descriptors used in this study. In general, judges tended to prefer the Control wine and the wine made with Tannat Skins, Oak Chips, and Tannin added. This study suggests that the effects of adding different sources of tannin are not additive but instead are complex and difficult to predict.

Read Full Report (PDF)

The Effect of Oak Adjuncts vs Hungarian Oak Barrels in Chambourcin Aging (2016)

This study examines the impact of aging in new Hungarian oak barrels vs aging in flex tank with Hungarian oak Fans on the chemical and sensory profiles of Chambourcin. Chambourcin wine was split into these vessels with the corresponding treatment. Due to the differences between aging in barrel and flex tank, the wine in flex tank required higher additions of sulfur dioxide. Not many phenolic or chemical differences exist between wines, except the wine aged in flex tank showed higher levels of anythocyanins. Judges found the wines were found to be significantly different (p<0.05), but there were no major preferences for one treatment over the other. There was a slight trend for the flex tank wine to show more Oak Character and less Fruit Intensity. Overall, flex tanks show promise in wine aging, but more work needs to be done to address oxygen ingress and headspace issues, as well as fine-tuning the use of oak adjuncts.

Read Full Report (PDF)

The Effect of Different Aging Vessels on the Sensory Qualities of Viognier (2016)

This study examines the effects of aging Viognier wine in concrete eggs, stainless steel barrels, and acacia barrels on the chemical and sensory qualities of Viognier. One lot of Viognier wine was split into these different aging vessels after a week of fermentation. The wine was aged in these vessels for approximately four months. No chemical differences could be found between wines, except that acacia barrels exhibited the lowest levels of dimethyl sulfide. Aging in acacia barrels tended to reduce Fruit Intensity and Overall Aromatic Intensity and increase Yeast Character. Stainless steel and concrete egg aging tended to help maintain Fruit Intensity and Aroma. In general, aging in acacia barrels was least preferred compared to other treatments. More studies on these different aging vessels should be performed, perhaps with different aging times and types of wine.

Read Full Report (PDF)

Sauvignon Blanc Clonal Investigation (2016)

This study examines the clonal differences between Sauvignon Blanc FPS 1, FPS 18, ENTAV 376, and ENTAV 241 planted in the same year in the same vineyard block. Grapes were harvested and pressed on the same day but kept separate, and all treatments between lots were kept the same. Yields were different between some clones, and the FPS clones tended to have higher malic acid and YAN. Clone 241 tended to have lower acidity and higher pH than the other clones, and the opposite trend was observed for FPS 1. Wines produced from FPS 1 and ENTAV 376 had the highest levels of 3-MH. Descriptive analysis found several differences between clones. Wine made with ENTAV 376 was highest in most sensory descriptors, and most people preferred Clone 376. However, these differences may not all be clonal, but could be due to variations between fermentations. As such, this study should be repeated in order to determine if clone 376 is truly much more aromatically intense.

Read Full Report (PDF)

The Effect of Timed Nitrogen and Sulfur Sprays on Sauvignon Blanc (2016)

This study examines the impact of timed Nitrogen and Sulfur sprays on the sensory and chemical attributes of Sauvignon Blanc. A mix of Nitrogen and Sulfur sprayed at 20% veraison and at 50% veraison were applied to 2 out of four segments of a vineyard block. The other segments were unsprayed. The grapes were harvested and processed identically. After racking off of gross lees, the lees were harvested, combined, and centrifuged to create a centrifugate juice (a mix of the lees from the control and sprayed grapes). No major chemical differences were found between the control and treated juice and wines, except that pH was slightly higher. The sprayed wine had a slightly higher level of 3-MH. However, the wine made from the combined lees centrifugate had the highest level of 3-MH and lower levels of 3-mercaptohexylacetate. Additionally, this wine had a longer lag phase during fermentation compared to the other two. Judges were generally able to distinguish between the unsprayed and sprayed treatments, and there was a tendency for the sprayed treatment to be preferred and the centrifuged treatment to be least preferred. The sprayed wine had slight tendencies to have higher Overall Aromatic Intensity, Herbaceous/Green character, and Varietal Character. There were slight trends for the centrifuged wine to have lower Tropical Fruit and Varietal Character than the other treatments, and higher Herbaceous/Green character. These tendencies were all very weak, however.

Read Full Report (PDF)

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

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

Read Full Report (PDF)

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.

Read Full Report (PDF)

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.

Read Full Report (PDF)