What Smoke Taint in Wine Tastes Like

Isabelle Lesschaeve Author

Smoke taint in wine results from smoke exposure due to wildfires occurring in wine regions. How to spot this new taint in wine?

Smoke taint in wine is not a new fault affecting wine quality. 

Its prominence has grown in the last decades due to the increased occurrence of ravaging wildfires in several wine regions. These fires have devastated millions of acres of land, impacted tragically many lives, and challenged in so many ways wine businesses on the West coast of the US and in the southwest of Australia. 

Wildfires are a natural process

of forest regeneration, but the ones we have seen since 2017 are the results of many years of drought attributed to climatic changes. 

In this article, you will learn:

• what smoke taint is in wine, 
• how grapes and wines get affected, and 
• which aromas to expect to experience in a smoke-tainted wine.

It is also my second contribution to address the question: 

'How might the Wine Aroma Wheel be seen relative to prominent trends in the past few years in the wine world, including specifically natural or low-intervention wine and climate change?'

How grapes get smoked?

Smoke taint in wine results from extended exposure to volatile phenols, which are odor-potent compounds emitted by wood-burning smoke. 


Because they are airborne, these compounds can travel miles away from the original fires and settle on remote grapevines. In contrast, vineyards close to the fires might not be heavily exposed. 
—>This is the first challenge for scientists and winemakers to determine if the grape production is at risk of smoke taint.

Once settled on the grape berries, the volatile phenols get absorbed through the skins, making thin-skinned grape varieties more susceptible to smoke impact. However, nature has prepared the plant to defend itself against such invasion; the berries block the phenols' negative impact by binding them with a sugar compound.
—> This defense mechanism is the second challenge for scientists and winemakers. Once bound to sugar, volatile phenols become more challenging to detect analytically or by tasting and therefore assess the risk of smoke influence on the harvest.

Once the berries get crushed, the phenols get released in the must. No remedial treatment is possible until the wine is finished. That is only when one can taste the likely impact of smoke on wine quality. Note that removing leaves and stems before pressing helps minimize the phenol release into the must.

Smoke taint in wine can vary from minimal to drastic

Minimally impacted wines will exhibit aromas like mesquite smoke, tar, or clove. These are also aromas that oak barrel aging can develop in the wine. Therefore, these smoke-related aromas might not affect our enjoyment of the wine.


Heavily impacted wines taste like ashes from an ashtray and can't be commercialized.



Moderately impacted wines will have a smoky, burnt, or medicinal aroma.


While young wines may only exhibit subtle smoke influence on their aromatic profile, it seems that the impact can develop with bottle aging. 
—> Taint development with aging is another challenge for winemakers. Do they take the risk of selling a wine that can turn bad?

Remedial treatments like fining agents or spinning cone technology can remove the volatile phenols from the affected wines; however, they also remove desirable color, mouthfeel, and aroma compounds.

No treatment specifically targeted to remove volatile phenols exists to this day; researchers work in tandem with the industry to find practical solutions quickly.

20 % of people don't detect smoke taint in wine

Low sensory detection thresholds

Compounds imparting smoke taint in wine are volatile phenols with low detection thresholds. 

The Australian Wine Research Institute (AWRI) published a fact sheet on 'Sensory Impact of Smoke Exposure". 

• Guaiacol and m-cresol can be detected when present in red wine at a concentration higher than 0.000023 ML/L. 
• Other smoke-taint compounds have higher thresholds, around 0.000064 ML/L.

These compounds in mixtures can impact wine even if their concentrations are below their detection thresholds. Their odor potency is cumulative!

Scientists have observed large variability in humans' ability to detect these compounds; the numbers above are averages. Some people will notice the compounds below these thresholds, and others won't be bothered at all.

Low acceptance by wine drinkers

AWRI also conducted a blind taste test with consumers. 

Eighty-two rosé wine drinkers took part in the study and evaluated five rosé wines:

• an unaffected Pinot Noir
• a smoke affected Pinot Noir
• 3 samples of the unaffected wine blended with 6.25%, 12.5%, and 25% of affected wines, respectively.

Consumers liked the sample containing the smallest proportion of smoked wine as much as the unaffected Pinot Noir. However, they didn't like the two other blends, and these consumers significantly disliked the smoked-affected wine. 

However, 21% liked the five wines equally, indicating that this group was either less sensitive to the smoke taint compounds or not bothered by them.

—> This variability in detecting or not the taint is another challenge for winemakers in their decisions to release or not a wine. Most likely, they choose the conservative route and discard any potential faulty wines.



How these data impact the Wine Aroma Wheel descriptors?

Adding "Ashy" to the Wine Aroma Wheel?

Mesquite smoke, tar, clove, smoky, burnt, medicinal, and ashy are the aromatic descriptors attributed to perceiving volatile phenols in wine.


Mesquite smoke and ashy are the two terms currently absent on the wheel. 

While mesquite smoke could be part of the more generic Woody/Burnt/Smoky category, I would support the addition of Ashy in this same aroma category. 

I noticed that wine tasters often asked me if the term tobacco evokes cigarette ashes when they use the Wine Aroma Wheel for the first time. 
It refers to dry tobacco leaves not consumed. 

Ashy aroma standard

Creating an aroma standard can be as simple as harvesting wood burnt ashes in a fireplace and place them in a container. People can train to recognize the ashy aroma by smelling the container and smelling the ashes diluted in wine for smell evaluation.

What to expect when purchasing wines from regions affected by wildfires?

The 2017 and 2020 vintages from the US West coast and the 2020 Australian vintages are possible candidates to smoke taint.


The likelihood to experience smoke-influenced aromas might be higher in wines from thin-skinned fruits or wines not exposed to oak barrels. Research showed that barrel aging could diminish the predominance of the volatile phenol effect; heavily toasted barrels can release these compounds.


Be assured that wineries have made their due diligence to eliminate any potential smoked-affected wines from the market. The risk of encountering a very faulty wine should remain low. 


Therefore being aware is important, but there is no urge to discard these vintages from your shopping list!

Published March 10, 2021

References

[1] AWRI. Smoke Taint https://www.awri.com.au/indust...

[2] The Complex Science and Evolving Toll of Smoke Taint | Wine Enthusiast, By Sean P. Sullivan https://www.winemag.com/2021/0...

[3] Smoke Taint's known knowns and unknown unknowns https://www.winebusiness.com/n... Discuss Progress During Unified Wine & Grape Symposium by Kerana Todorov January 28, 2021

Categories: wine aroma, wine aroma wheel