UBCO studies smoke tainted wine

Grape growers have long sought to protect their crops from the effects of wildfire smoke and new research from UBC’s Okanagan campus is giving them new insights.

In a recent study, researchers at UBC Okanagan and their industrial partner Supra Research and Development examined what happens to wine grapes after they are exposed to wildfire smoke. They determined that volatile phenols—chemicals in the smoke that can give wine an off-putting smoky flavour and aroma known as smoke taint—are absorbed quickly and remain in the grape long after the smoke has cleared.

“The biology of how wine grapes respond to smoke exposure is poorly understood,” says Wesley Zandberg, assistant professor of chemistry at UBC’s Okanagan campus. “Winemakers know that grapes grown in smoky conditions can lead to smoky-flavoured wine although the grapes themselves taste normal, and how or why this happens has largely remained a mystery.”

To better understand the process, Zandberg worked with PhD student Matthew Noestheden and research associate Eric Dennis to collect samples of Cabernet Franc grapes after exposing them to simulated forest fire smoke. They then tested for the presence of volatile phenols at several time points after smoke exposure and in wine made from the same grapes. 

“We found 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 we can’t taste or smell,” says Noestheden. “Once there, the concentrations remained unchanged in the grape throughout its development. Only when the grapes were fermented into wine could the smoky-flavoured volatile phenols be detected.”

Noestheden says the resulting wine taste is, "like an ashtray, or a barnyard, or a band-aid.  Obviously these are bad things."  No need to fear the 2017 lines of wine in the Okanagan though.  He says the smoke that lingered over us for much of last summer came from other areas, and smoke that well traveled can los a lot of the chemical potency needed to affect the grapes.

The UBCO researchers' next step is to create either a preventative method or a solution during wine production.  Noestheden hopes to either, "some sort of protective spray to protect the grapes or, on the flipside, in winery solutions can we do something to the grape juice or as part of the fermentation process, to limit the impact that the smoke exposure can have."