Matthew Knight
18/08/2026
How Wildfire Smoke Affects Wine
Smoke taint is an unwanted smoky, burnt, medicinal or ashy character that can develop in wine after grapes are exposed to smoke, most commonly from wildfires.
It happens when smoke-derived compounds enter grape berries, bind to their sugars and later reappear during fermentation, ageing or tasting.
That sounds straightforward. It is anything but. A vineyard can sit beneath visible smoke and still produce clean wine, while exposure much earlier in the growing season than previously thought can create serious problems.
Here is how smoke taint really works, how winemakers detect it and what it means for wine collectors and investors.
| Question | Short answer |
|---|---|
| What causes smoke taint? | Grapes absorb volatile phenols released when woody material burns. |
| What does it taste like? | Smoky, burnt, medicinal, tarry or ashy, often with a persistent aftertaste. |
| Can you see it on grapes? | No. Visual inspection and the smell of fresh grapes are unreliable. |
| Does smoke near a vineyard always cause it? | No. Smoke composition, concentration, duration, timing and winemaking choices all matter. |
| Can laboratories test for it? | Yes. Laboratories analyse free volatile phenols and smoke-related glycosides. |
| Can it be removed? | Its impact can sometimes be reduced, but there is no guaranteed cure. |
| Does it affect the next vintage? | Current research has found no evidence of smoke compounds carrying over from one season to the next. |
Smoke taint is not simply a layer of soot sitting on the outside of a grape.
When wood and other vegetation burn, the lignin within the plant material releases airborne compounds known as volatile phenols. These include guaiacol, cresols, syringol and methylsyringol.
The process then unfolds in four stages.
Fresh smoke containing a high concentration of volatile phenols moves through or settles around the vineyard.
Smoke that has recently come from burning woody material generally presents a greater risk than older, widely dispersed haze.
Research indicates that the main route into the fruit is directly through the waxy outer layer of the grape berry.
The latest Australian Wine Research Institute guidance found no significant movement of volatile phenols from smoke-exposed leaves into the fruit. The berries themselves are the primary point of entry.
Once inside the berry, the grape rapidly attaches sugar molecules to many of the volatile phenols. This creates compounds called phenolic glycosides.
In this bound form, the compounds may have little or no obvious smoky aroma. A grape can therefore smell and taste relatively normal while still carrying smoke-taint precursors.
During fermentation, some of the glycosides can break apart and release volatile phenols into the wine.
Further release can also occur in the mouth. Enzymes and bacteria in saliva can separate certain phenols from their sugars, creating a smoky or medicinal flavour as the wine is tasted.
This explains why a wine can smell clean at first but develop an unpleasant ashy character across the palate.
The character varies according to the compounds present, their concentration, the wine style and the sensitivity of the person tasting it.
Common descriptions include:
Guaiacol is commonly associated with smoky and medicinal notes, while cresols can produce tarry, medicinal or bandage-like characters.
Several compounds can also work together. According to the AWRI’s sensory research, multiple volatile phenols below their individual detection thresholds may collectively produce a noticeable smoky or medicinal flavour.
This helps explain why smoke taint cannot be assessed by looking at one compound in isolation.
Not every smoky note in wine is a fault.
Oak barrels, toasted wood and certain grape varieties can produce attractive aromas of toast, cedar, clove, vanilla or woodsmoke. These characters are intentional and should feel integrated with the fruit.
Smoke taint is different.
| Smoke taint | Oak or toasted-barrel character |
|---|---|
| Caused by smoke compounds absorbed by grapes | Created through deliberate contact with toasted oak |
| Often ashy, medicinal, tarry or burnt | Commonly shows toast, cedar, vanilla, spice or clove |
| Can create a lingering, unpleasant finish | Should be balanced and integrated |
| Considered a wine fault when perceptible | Usually part of the intended wine style |
Laboratory interpretation can become more complicated after oak ageing because oak can contribute some of the same volatile compounds being measured. This is why testing results need to be considered alongside the wine’s history and sensory assessment.
No. Seeing or smelling smoke does not prove that the grapes or resulting wine will be tainted.
Risk is shaped by several overlapping factors.
Fresh smoke from recently burnt vegetation usually contains more free volatile phenols than smoke that has travelled a long distance.
The fuel source and combustion conditions also affect the chemical composition of the smoke.
Dense smoke or repeated exposure generally presents more risk than a short period of light haze.
However, visual smoke density and conventional air-quality readings cannot reliably predict what will happen inside the grapes.
Older guidance often presented the period shortly after véraison, the stage when grapes begin to ripen and change colour, as the main danger point.
The latest research shows the risk window is more complicated.
Data from the 2019/2020 Australian fires demonstrated that exposure before véraison can still produce perceptible smoke characters. In some heavily affected vineyards, early-season smoke had serious consequences several months before harvest.
It is therefore unsafe to assume that early smoke cannot affect the eventual wine.
Different varieties may absorb and process smoke compounds differently, but variety alone cannot reliably predict the outcome.
Recent studies involving Chardonnay, Pinot Noir and Shiraz found smoke characters in wines from all three varieties under certain conditions. Researchers are continuing to investigate the influence of berry size, skin properties, clone and vineyard management.
Red wine is frequently considered more vulnerable because it is normally fermented in contact with grape skins, where many smoke-related compounds accumulate.
White wines generally have less skin contact and may show less intense smoke character. That does not make white grapes immune. Smoke-affected Chardonnay and other white varieties can still produce noticeably tainted wine.
How the fruit is picked, pressed, fermented and treated can substantially change how much smoke character reaches the finished wine.
This is one reason two producers working with grapes from the same fire-affected region can achieve very different results.
Winemakers cannot rely on the appearance of the vineyard, local air quality or tasting unfermented grapes.
A proper assessment normally combines chemical analysis with a small-scale fermentation and sensory evaluation.
Specialist laboratories look for two main groups of smoke markers.
Free volatile phenols
These include guaiacol, methylguaiacol, cresols, syringol and methylsyringol. Some contribute directly to smoky, medicinal or tarry aromas.
Phenolic glycosides
These are sugar-bound compounds that may act as smoke-taint precursors. Important markers include syringol gentiobioside, cresol rutinoside and guaiacol rutinoside.
The AWRI recommends testing both free volatile phenols and non-volatile glycosides, rather than relying on one or two headline compounds.
Results can then be compared with established background levels from grapes that have not been exposed to smoke.
A laboratory result does not always tell the whole story. Grapes naturally contain low concentrations of some smoke-related compounds, and results can vary according to variety, region and analytical method.
Producers can therefore make a small experimental batch of wine from the affected grapes. Fermentation helps reveal compounds that were hidden in their sugar-bound form.
The test wine can then be assessed chemically and tasted by an experienced sensory panel.
There is no universal number that guarantees every wine will taste tainted.
Interpretation must account for:
This makes expert interpretation just as important as the raw result.
At present, there is no proven vineyard treatment that guarantees protection against smoke taint.
Horticultural barrier sprays have been investigated, but updated AWRI guidance says research has not yet demonstrated a reliable protective effect.
Scientists are still looking for better answers. In 2026, researchers at UC Davis and the US Department of Agriculture began evaluating whether a calcium spray could strengthen grape skins and reduce smoke absorption. The UC Davis trial remains under analysis, with full findings expected after the experimental wines have been assessed.
For now, monitoring, representative sampling and rapid testing remain the most dependable options.
There is no single treatment capable of reliably restoring heavily tainted fruit or wine to its original quality.
Winemakers may be able to reduce the impact, particularly when the exposure is limited and action is taken early.
Common techniques include:
These approaches seek to limit the extraction of smoke-related compounds from the skins.
Activated carbon can adsorb some undesirable compounds in juice or wine.
The drawback is that carbon is not selective. It can remove colour, fruit aromas and desirable flavours alongside the smoke compounds. Producers therefore need to conduct small trials before treating a larger volume.
A limited amount of affected juice or wine may be diluted with a much larger volume of unaffected wine.
The appropriate ratio depends on the strength of the smoke character and the style of the clean wine. Blending is unlikely to be commercially or stylistically appropriate for every producer.
Reverse osmosis, nanofiltration, glycosidase enzymes and oak treatments have all been investigated.
Results have been mixed. Wine Australia’s treatment guidance states that there is currently no silver bullet for removing smoke taint from finished wine.
When fruit is severely affected, the most responsible decision may be not to produce the intended wine at all. Some grapes or wine may instead be diverted into distillation or another use.
Washing can remove loose ash, dust or material sitting on the surface, but it cannot be relied upon to prevent smoke taint.
The volatile phenols responsible for the fault are absorbed through the berry’s waxy cuticle and become bound inside the grape. Once that has happened, rinsing the surface will not remove the internal compounds.
This is why smoke taint is fundamentally different from visible ash contamination.
Bottle ageing is not a dependable cure.
A 2025 study of smoke-affected wines found that ageing altered the sensory profiles of different wines in different ways. As fruit aromas diminished, smoke character became more prominent in some wines. In other examples, including some Shiraz wines, smoke-related attributes became less obvious.
The conclusion for collectors is simple: never assume that a smoky or ashy wine will become clean with time.
Smoke-related glycosides can remain in wine, and changes in the balance between fruit, oak and smoke compounds may make the fault more noticeable rather than less.
Wildfire headlines should not be treated as proof that an entire region or vintage has been compromised.
Smoke exposure can differ between neighbouring vineyards, grape varieties and even individual blocks. Producers may also harvest selectively, declassify affected parcels or decline to release a flagship wine.
That distinction was important during the Bordeaux wildfires of July 2026. Although the fires came close enough to generate alarming headlines, there was no indication at the time of our analysis that the vineyards responsible for Bordeaux’s most collectible wines had been directly affected.
California has faced the same challenge more frequently. Our earlier analysis of wildfires and the Californian fine wine industry shows why producer-level assessment matters more than broad assumptions about a region.
Collectors assessing a fire-affected vintage should consider:
Lower production can create scarcity, but scarcity alone does not make a wine investable. Quality, reputation and sustained demand still matter.
Smoke taint is primarily classified and managed as a sensory and commercial-quality fault. It should not be confused with the serious direct health risks created by inhaling wildfire smoke.
Industry guidance focuses on the wine’s undesirable flavour and consumer acceptance. Producers must still follow appropriate testing and food-safety guidance when fruit has been exposed to a fire event.
Not reliably. Smoke-related phenols can become bound to sugars inside the grape, making the problem difficult to detect before fermentation.
No. The outcome depends on the smoke’s freshness and composition, exposure level, duration, grape development, weather conditions, variety and winemaking decisions.
Red wines often present a greater risk because they ferment with their skins. White wines can still be affected, particularly following significant smoke exposure.
Its impact can sometimes be reduced through careful processing, activated carbon, blending or other treatments. Heavily affected fruit or wine is unlikely to be restored completely without also compromising desirable qualities.
Not predictably. Research shows that it can become more obvious in some wines as fruit aromas fade, while becoming less prominent in others.
Current research has found no evidence that volatile phenols or their glycosides carry over inside the vine from one growing season to the next.
Smoke taint is one of the wine industry’s most complex faults because it can remain hidden until fermentation or even until the wine reaches the drinker’s mouth.
Visible smoke does not prove a vintage has been ruined. Equally, clean-looking grapes do not guarantee that smoke compounds are absent. Reliable conclusions require representative sampling, laboratory analysis, small-scale fermentation and experienced sensory assessment.
For collectors and investors, the lesson is not to avoid every region touched by wildfire. It is to look beyond the headline and assess the individual producer, vineyard and wine.
If you are considering wine from a fire-affected region, Moncharm can help you assess the producer, vintage, provenance and secondary-market evidence. Book a free consultation or download our fine wine investment guide.
10 Sep 2026
