How wildfire smoke ends up in wine, and how we measure it
Wildfire smoke near vineyards is becoming a familiar part of the growing season. In recent years it has reached wine regions in Northern California, southern Australia, and, most recently, parts of southern Europe near Bordeaux and Madrid. Each time, the fire itself is not the only concern. Smoke can settle into the grapes long before anyone opens a bottle, and change the wine without it being obvious at first. Here is how that actually works, and how we measure it.
What smoke taint actually is
When wildfire smoke drifts over a vineyard during ripening, it carries compounds called volatile phenols (guaiacol is the best known), released when wood and plant material burn. These settle on the grape skin and are absorbed into the fruit. The grape then does something protective: it binds a large part of what it absorbed to sugar molecules, turning it into a form that carries almost no smell or taste. That is why the berry itself can seem unaffected.
For a long time, the assumption was that smoke also travels from the leaves into the fruit. A new study (Food Chemistry, 2026) tested that directly, and found the opposite: grapes stayed clean even when the leaves absorbed smoke. The real route is the berry itself. Vines with fewer leaves actually showed more damage, not less, because there was less canopy to catch the smoke before it reached the fruit.
Why it hides until fermentation
Fresh fruit can taste clean. So can the must. That is because the volatile phenols are still locked in their bound form. Fermentation breaks those bonds, and so does time in the bottle. Acid and enzymes release the volatile phenols, and with them the smoky, ashy, medicinal character and dry finish of smoke-affected wine. A wine can pass an early check on the must, and still develop taint later. That is why one test at the start of the season is not enough. Testing is not an extra step. It tells you where you stand, and gives you time to prepare, before the wine is finished, not after. We can help you with that.
How we measure it at Meron
We measure the smoke-related compounds present in the wine at Meron using GC-MS/MS. The results provide insight into the wine’s condition at the time of analysis. However, once these compounds are present, their concentrations will never decrease.
Numbers alone do not tell the whole story. The perception of smoke taint also depends on the grape variety and the individual sensitivity of the taster. That is why we combine laboratory results with an assessment by a trained sensory panel. Together, these form the basis of a report with concrete recommendations and actionable next steps.
Test before you bottle. Protect the quality of your wine before it’s too late.
By analysing a tank sample before final bottling, you give yourself the opportunity to assess smoke taint, make informed decisions and take corrective action where possible. Once the wine is bottled, your options are far more limited.
Don’t leave the final quality of your wine to chance. Send us a tank sample and let Meron help you make the right decisions before bottling.
Why this matters every fire season
No one welcomes a fire season. But knowing in advance is better than finding out once the wine is already bottled. Wildfire smoke during the growing season has affected vineyards in Australia, California and parts of southern Europe in recent years. Testing early, and again after fermentation, gives you as producer time to act while the wine is still a decision rather than a finished bottle: keeping affected lots separate, adjusting a blend, or choosing a different route for fruit that will not meet the intended quality level. That is what the data is for. Not the number itself, but a better informed decision for you.
Frequently asked questions
What is smoke taint in wine?
Smoke taint is the smoky, ashy or medicinal character that wildfire smoke can leave in wine. It comes from volatile phenols, compounds such as guaiacol and 4-methylguaiacol, that settle on grape skins during a smoke event and are absorbed into the fruit.
What causes smoke taint?
Burning wood and plant material release volatile phenols into the air. When smoke drifts over a vineyard during ripening, these compounds land on the grape skin and pass through its surface, where part of them is converted into glycosides, bound forms with little smell or taste on their own.
Can you taste smoke taint before fermentation?
Not reliably. Fresh fruit and must can taste clean while the volatile phenols are still locked in their bound form. Fermentation and time in bottle break those bonds, releasing the smoky character later, sometimes well after an early check would have suggested the fruit was fine.
How is smoke taint measured?
At Meron, we use GC-MS/MS technology with very low detection limits to determine whether compounds such as guaiacol are present in the wine.
We communicate the results in our report using an indicator with a defined threshold value. As the guaiacol concentration approaches this threshold, trained sensory panelists are increasingly likely to detect its presence. Once the concentration exceeds the threshold, consumers may also begin to perceive undesirable sensory characteristics in the wine.
Consumers may not identify the compound as guaiacol, of course, but they are likely to experience the wine less positively. And a negative tasting experience is unlikely to encourage a repeat purchase.
Why can smoke taint appear after bottling?
Because the compounds responsible were still bound and largely undetectable. Acid and enzymatic activity during fermentation and aging gradually release them, which is why one test at harvest is not enough on its own.