WORLD OF WINE: If wildfire smoke bothers eyes, if could affect wine, too

The wildfires of this past summer in western Canada, and the recent tragedy of wildfires in California, have affected growers and producers of wines. The worst case of destruction was in the Napa and Sonoma wine growing regions where vineyards, wineries, homes and lives were destroyed.

Where vineyards were not directly threatened by fire destruction, but witnessed their vines and grapes shrouded in smoke and in some cases covered with ash, the smoke scent will be noted when the wines made from those grapes are opened.

When such an affected bottle is opened, the strong off-note is perceived, which is associated with terminology of ash or ashtray. The result is a strong reduction in the quality of the wine.

Originally thought to be the result of barrique-produced (smaller barrels) wine that have a “smokey” taste of their own, the blame was placed on over-toasting.

Not so, says Technical University of Munich professor Wilfred Schwab and his colleagues.

According to Schwab, as an aromatic substance, smoke is volatile and attached to sugars found in the foliage and fruits. The aromatic substances can then be detached from sugar and released, via a process called glycosylation, which is a series of chemical reactions where an enzyme is responsible.

That responsible enzyme then acts as a biocatalyst, which makes the link with the sugar molecules giving their smoky off-notes more water solubility, making them no longer volatile.

In essence, you could walk into a smoke-encased vineyard, pick a grape, pop it into your mouth and not detect any smoke taint. It is when the fermentation takes place that the water-soluble smoke molecules become detached – making them volatile – and the ashtray aroma is detected.

Greg Jones, a professor from Southern Oregon University and research climatologist, says some vintners combat the issue by using a high-volume cold-water wash, harvesting by hand, removing leaf litter in the grape load and reducing the amount of contact the skins have with the juice. At best, though, this sometimes works.

Enter genetic engineering of the yeast used in fermentation. Such yeast would ignore the sugar attached to smoke molecules, or it may be to use grape plants that produce less of the enzyme responsible for the binding of sugar with smoke.

Scientists in California, Oregon and Washington, along with those in Australia and Italy, will keep pushing the envelope to reach a solution acceptable to all.

In the meantime, if you are shy about encountering the ashtray taste, stay away from red wines in those wildfire prone areas, and opt instead for the white wines where skin contact is limited.

Wine is considered a natural product from nature with minimal intervention from growers and vintners. Perhaps the answer lies somewhere in figuring out how to limit wildfires.  

Ron Smith, a retired NDSU Extension

horticulturist, writes weekly about his love of wine and its history. Readers can reach him at