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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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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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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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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