Thomas Henick-Kling, professor of enology
Washington State University, Ste. Michelle Wine Estates Wine Science Center
2710 Crimson Way
Richland, WA 99354
Summary: This has been a very INTERESTING vintage in Washington State. In the end, mother nature was very kind and brought us some great ripening weather and I think we can look forward to many excellent wines from 2022.
One part of this interesting growing season that raises a bit of concern for me was the extreme heat we had in July and August.
There is the direct impact of heat on the fruit which can cause the formation of cooked, jammy, fruit flavors and a lack of tannin development. In Riesling is causes the formation of TDN which at high concentrations give the wines a very dominant, candle wax, wet wool, kerosene, or gasoline aroma. This can only be avoided by providing excessive water stress and possibly nutrient stress as the fruit ripens. TDN rarely occurs in grape berries. It is produced from glycosylated carotenoid-derived precursors during fermentation and wine aging. We don’t know if heat increases those precursors, but light exposure does, at least before veraison (Markus Keller, personal communication). There is no after vinification treatment to suppress the expression of these flavors.
The other effect of this high heat was potentially high water stress. Excessive water stress can lead to the formation of the Atypical Aging flavor defect ATA. Sometimes, ATA is also called UTA and premature aging. These are all the same flavors. All white wine grape cultivars and Pinot Noir and possibly Syrah are susceptible to this flavor defect. The good news is that there are two ways to avoid this dominant flavor taint: 1) limit the water stress in the vineyard and 2) add ascorbic acid (vitamin C) early in the wine’s development.
Early addition of ascorbic acid (vitamin C) can delay the expression of ATA flavors for 2 years and even longer. To be most effective, ascorbic acid should be added as early as possible, as soon as the wine has stable free SO2. You should add a minimum of 100 mg/L ascorbic acid. Since ascorbic acid slowly degrades in wine, I like to add a little more, about 150 mg/L. This addition is small enough that it will not make your wine perceptibly more acidic, but it is effective in locking the ATA development and it helps protect the freshness of your other wine flavors as well.
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