UBC study looks at how wildfire smoke affects B.C. wine

Hints of blackberry with top notes of cherry and ... wildfire smoke?

That might sound like a cheeky way to describe a B.C. vintage, but smoke taint is a significant problem for many of the province’s winemakers.

So UBC Okanagan researchers have been studying why grapes exposed to wildfire smoke can taste OK, but the wine has an ashy, unpleasant flavour.

What they found is that volatile phenols — chemicals in the smoke that can give wine an off-putting taste and aroma known as smoke taint — are absorbed quickly and remain in the grape long after the smoke has cleared.

One of the lead authors, Matthew Noestheden, says for their latest study that they went out to several vineyards in Kelowna in 2016 and exposed some grapes to smoke deliberately using a fuel source that is similar to the area, such as Ponderosa pine.

“We followed what happened to these chemicals that lead them to that ashy, barnyardy aroma from the time they are exposed through to fermentation. That had not been done before.”

They discovered that once the grapes were exposed to smoke, the volatile phenols were rapidly metabolized by the grape and stored, in part, in a sugary form that people can’t taste or smell. Only when the grapes were fermented into wine could the smoky-flavoured volatile phenols be detected.

The latest study was published in the Journal of Agriculture and Food Chemistry. Noestheden, a PhD student of chemistry, and his professor, Dr. Wesley Zandberg, had a previous study about discovering a test for smoke taint in grapes published in the same journal in October. The study was funded by Supra Research and Development in a bid to provide the wine industry with a test that can detect whether the grapes will be affected by smoke taint.

Noestheden said testing is already underway with some vineyards, but he noted that more research is needed to ensure the test is 100-per-cent accurate.

He said the idea is that winemakers won’t have to wait until harvest to know whether their grapes are tainted.

Heavy smoke blanketed the Okanagan much of last summer during B.C.’s worst wildfire season.