The effect of early leaf pulling on thiol production in an Oregon Sauvignon Blanc (2018)

Chemeketa Community College, Scott Dwyer

Thiols have become a defining characteristic of aromatic Sauvignon Blanc wines. Early defoliation in the fruit zone has been shown to increase thiol production in South African Sauvignon Blanc (Šuklje et al 2104). In this study, leaves were removed from the east side of the fruit zone immediately after fruit set. Control rows had no leaf pulling. Resulting wines showed no differences in major chemistry, however wines with leaves pulled had lower concentration of thiols. Sensory analysis of resulting wines showed higher thiol intensity in control wines, with these wines also scoring significantly higher for aromatic intensity and acidity.

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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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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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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.

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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.

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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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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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Concrete vs. Stainless Steel Aging with Sauvignon Blanc (2014)

This study compares the chemical and sensory effects of aging Sauvignon Blanc wine in concrete and stainless steel vessels.  Although there were no chemical differences between the wines, there were significant sensory differences between the wines.  This seems due in part to the stainless steel-aged wine being slightly oxidized, but there were reports of the concrete egg-aged wine having a creamier and fuller mouthfeel.

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