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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Leaf Pulling Graph 1.jpg

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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