Questions About Smoke Taint
I am getting a few questions about smoke taint. Some have expressed concern that the 2017 wines from the Napa Valley may be tainted with smoky aromas because of the numerous wildfires this October.
To be clear, it is estimated that 90% of the Napa Valley fruit had been picked and crushed before the mid-October fires that devastated many in the Napa and Sonoma valleys. Most of the wines were safe in cellars.
We had picked the Muir-Hanna Chardonnay and the St. Helena Merlot in September. However, we still had to pull in the Red Hen Vineyard Cabernet Sauvignon.
Mechanics of Smoke Taint
Smoke taint can be an issue earlier in the ripening of the grape. Spring and summer fires can deposit smoke and ash on the vine’s leaves, allowing the vine to draw the chemical compound into the physiological makeup of the grape. At that point, it can become part of the aroma compounds found in the phenolics of the grape, mostly in the cell walls just under the skin.
Our Pick and Crush
The Cabernet Sauvignon was picked on Thursday, October 12, just a few days after the fires started. The fruit was already mature. The smoke and ash settled on the grapes, alongside the dust.
Pulling in Cabernet Sauvignon During Fires October 12, Smoke and Red Hen Vineyard behind me.
To be safe we lightly rinsed the grape clusters and let the water drain off. We then bled off 15% of the juice (to create a higher skin to juice ratio) and then crushed. I’ve learned since that the rinsing probably didn’t do much, but no harm either.
We took samples pre- and post-rinse for two chemicals markers responsible for smokey aromas; guaiacol and 4-methylguaiacol. Low levels of these already exist in sound wines, usually less than 5 micrograms per liter. As assumed the presence of these compounds was minimal, less than 1.5 micrograms in the pre-rinsed and less than 1.0 microgram in the rinsed samples.
The wines of 2017 are already showing their potential and are developing nicely. Let’s check back in 24 months when we are preparing them for bottle.