394 THE ADVOCATE
VOL. 76 PART 3 MAY 2018
The summer of 2017 in B.C. was one with “smoke on the water, fire in the
sky”. Wildfires engulfed parts of western Canada and the western states,
particularly in California, Washington and B.C. It was hard on the heels of
widespread flooding in the Okanagan and Thompson areas. As I write this
article, there are warnings of more flooding in 2018, and, if the experience
of recent years repeats, there will be fires to follow, with lingering smoke
filling the sky.
Many of the 2017 fires were interface fires, which in Napa and Sonoma
burned several wineries and vineyards. In the Okanagan and Similkameen,
there were weeks of heavy smoke that drifted northward from the U.S. or
south from the Thompson region. Australia and Chile have also had intense
fire seasons over the past few years in areas adjacent to wine-growing
regions.In some cases, this has had a negative effect on the quality of wines.
They have displayed aromas and flavours that have been dubbed as “smoke
taint”. When and how that occurs, and the steps that can be taken to minimize
its effect, form the subject of this article.
So what does a wine with smoke taint smell and taste like? Try descriptors
like “campfire” or “burnt” or in some cases “antiseptic” or “medicinal”,
with muted fruit aromas and flavours.
“Smoke taint is pretty obvious,” said Rick Davis, owner of Calstar Cellars
in Santa Rosa, Calif. “The best descriptor I’ve heard for the flavor profile
of a smoke-tainted wine was that if you’re particularly fond of licking wet
ash trays, you’ll like this wine.”1
Research into the physiological reasons for this phenomenon began in
the early 2000s, particularly in Australia, where bushfires are a way of life,
but also due to government-initiated “controlled burns” in summer. Fortunately,
wineries have convinced governments to hold off on those burns
until after harvest. In more recent years, research has extended to California,
Washington and B.C.
I spoke with Dr. Kevin Usher, a research scientist in phytochemistry
(chemicals derived from plants) at the Summerland Research and Development
Centre and one of B.C.’s authorities on smoke taint.
Smoke contains hundreds, probably thousands of compounds, called
volatile phenols, that can get into fruit. In the vineyard, these compounds
can permeate the grape skins and rapidly bond with the sugars inside the
grapes to form molecules called glycosides. As Dr. Usher put it, “grapes love
phenols” and, as a show of that affection, attach sugars to them.
This process, called glycosylation, “binds” the phenols so they are no
longer “free” (grapes apparently like a kinky kind of love), meaning they are
not volatile and their smokiness cannot be detected in the grape by smell or