The Effect of Juice Turbidity on Aroma Development in Aging Sauvignon Blanc (2017)

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.

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Comparison of Juice Settling Techniques (Cold Settling vs Flotation) (2017)

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.

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Sauvignon Blanc Production with Lafazym Arom (2017)

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.

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

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

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

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

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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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The Impact of Increased Sulfur Dioxide at Crush on Color and Tannin Extraction (2017)

High concentrations of sulfur dioxide at crush can enhance color extraction during maceration. This study examines the impact of high levels of sulfur dioxide at crush on color and phenolic extraction. Pinot noir from a single vineyard block was sorted, destemmed, and divided into 4 T bins. The T bins received either 50ppm, 100ppm, 150ppm, or 200ppm sulfur dioxide at crush. All other treatments between wines were identical. 150ppm and 200ppm sulfur dioxide seemed to induce a slightly longer lag phase relative to lower levels of sulfur dioxide, but otherwise fermentation kinetics were similar. Wine chemistry was similar between treatments, except that TA and lactic acid decreased slightly with increasing levels of sulfur dioxide. Total, free, and molecular sulfur dioxide increased with increasing concentrations added at crush. Color intensity, anthocyanins, catechin, epicatechin, and tannin all seemed to increase as well from increasing sulfur dioxide usage. Overall, lower rates of sulfur dioxide tended to have higher Fruit Intensity. 100ppm of sulfur dioxide had a strong tendency for the highest Fruit Intensity and lowest Herbaceous/Green character. Body tended to be higher at 100ppm as well. Higher rates of sulfur dioxide addition (above 100ppm) tended to increase Astringency. The perception of Acidity may have been increased by higher sulfur dioxide levels as well. The most preferred wine was the wine produced with 100ppm of sulfur dioxide. More studies should be performed to evaluate the use of sulfur dioxide at crush, particularly with other grape varieties.

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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.

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Skin Contact vs Traditional Pressing of Petit Manseng (2016)

This study compares the effects of destemming and cold soaking Petit Manseng Grapes for 6 hours prior to pressing compared to directly pressing whole clusters. Juice produced with skin contact showed higher pH without much change in TA. The wine which underwent skin contact showed much lower TA and much higher pH. Skin contact also increased color intensity, catechin, tannin, caffeic acid, gallic acid, and astilbin. Caftaric acid was decreased by skin contact. This loss in caftaric acid and gain in caffeic acid could be due to equilibrium pressure. Sensory testing found the wines to be significantly different. Direct to Press wines had a slight tendency for higher Tropical Fruit aromatics, and a strong tendency for these wines to have higher Overall Aromatic Intensity. Skin-Contacted wines had strong tendencies towards increased Bitterness, and a slight tendency for higher Astringency. In general, people tended to prefer wines made from direct pressing. Studies of this kind, in conjunction with phenolic fining studies, should be performed in the future.

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Comparison of Juice Clarification Techniques (Cold Settling vs. Flotation) on Chemical and Sensory Aspects of Vidal Blanc (2016)

This study compares the efficacy of juice clarification with flotation to that of cold settling. The
cold-settled juice fermented slightly slower. No notable chemical differences were apparent between juice and wine, except that cold-settled juice produced wine with a higher degree of cold stability. The TA was higher for the float-clarified wine. Wine produced from flotation resulted in less losses to gross lees, and reduced the need for chiller load. It could potentially reduce turn-around time as well, but this was not characterized fully in this study. A significant difference (p<0.001) between wines was found in triangle testing. Although descriptive analysis showed no strong trends for the descriptors used in this study there was a slight trend for wines produced with flotation to have higher Fruit Intensity as well as Overall Aromatic Intensity. In general, there was not a noticeable preference for the floated wine over the cold settled wine. 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.

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The Effect of Juice Turbidity on Aroma Development in Chardonnay (2016)

This study compares the effects of fermenting Chardonnay juice at a low turbidity, medium turbidity (110NTU), and high turbidity (225 NTU). Juice from the same pick of Chardonnay was settled and racked into barrels. Turbidity was adjusted by adding back fine lees to the juice. All other treatments between wines were the same. The 110 NTU and 225 NTU wines had no chemical differences. The wines were not found to be statistically different at tastings, and those who were able to correctly distinguish the wines had a slight tendency to prefer the wine made from higher turbidity. This wine had a slight trend to be higher in Overall Aromatic Intensity and lower in Bitterness. More work is needed here to obtain a better understanding of the effect of juice turbidity on wine quality. It may be that the turbidity difference in this study was too small to have a great effect on the wine flavor profile.

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The Effect of Juice Turbidity on Aroma Development of Sauvignon Blanc (2016)

This study compares the effects of fermenting Sauvignon Blanc juice at a low (50 NTU) or high turbidity (250 NTU). Juice from the same pick of Sauvignon Blanc was settled and racked into stainless steel barrels. Turbidity was adjusted by adding back fine lees to the juice. All other treatments between wines were the same. No major chemical differences could be found between juice or wine, except that the juice with higher turbidity had slightly higher YAN and its wine had slightly lower alcohol. High turbidity greatly increased 3-mercaptohexanol and 4-methyl-4-mercaptopentan-2-one, but decreased 3-mercaptohexylacetate. Triangle testing suggests that the wines were significantly different (p<0.001). No major preference could be seen for one wine over the other. No major trends could be found for the descriptors used in this study, despite the wines being found to be significantly different. There was a slight tendency for the High NTU wine to have more Varietal Character and Overall Aromatic Intensity, while having less Body.

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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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Hyperoxidation Fining Trials of Petit Manseng (2016)

This study examines the effect of adding fining agents to hyperoxidized Petit Manseng juice on the sensory and phenolic characteristics of Petit Manseng. After reducing the temperature to 10-12°C, Petit Manseng juice was hyperoxidized by pumping four volumes of juice over a sump screen, taking about 10 minutes. After this process, juice was very brown and then sulfur dioxide was added at 50ppm. Juice was then split into two vessels, one of which was fined with casein, PVPP, and bentonite to remove solids and phenolic compounds. All other treatments between juices and wines were identical. Overall, no major chemical, color, or phenolic differences were observed between the wines, suggesting that fining juice after hyperoxidation does not do much to alter the color and phenolic properties of the wine. Triangle testing suggests that the wines were significantly different from each other (p<0.001), likely due to a difference in turbidity. No preferences could be seen for one wine over the other. The fined wine had a slight tendency for lower Tropical Fruit and increased Bitterness/Astringency.

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Chardonnay Juice Fining with Oenolees (2014)

Chardonnay juice was treated with Oenolees (Laffort) partway during fermentation, and the finished wine was compared to Chardonnay from the same pick that had not had Oenolees addition. Although there was no real chemical difference between the wines, there was a significant sensory difference between wines.  No preference or descriptive data was taken.

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Glutathione Addition in Viognier – FreshArom (2014)

This study compares the chemical and sensory aspects of Viognier wines whose juice had been treated with FreshArom (Laffort), a glutathione product.  Glutathione is thought to help prevent oxidation in juice.  No chemical differences were observed in the wines except that titratable acidity was higher in the wine treated with FreshArom.  Significant sensory differences were observed between the wines.  However, preference and descriptive data were not collected, so the effect of FreshArom in this study is still undetermined.

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Press Enzyme Comparison: Cinn-Free vs. Lafazym Press (2015)

The effect of press enzymes Cinn-Free (ScottLabs) and Lafazym Press (Laffort) on finished Sauvignon Blanc wine were compared.  There were no chemical differences between the wines except that the Lafazyme-treated juice had a slightly higher titratable acidity.  There were no significant sensory differences between the wines, but there seemed to be a slight preference for Lafazyme.  No yield comparisons were made.

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