How Do Wildfires Affect Wine? Chromatography Explores

From floral and fruity to honeyed and heady, wines can exhibit a vast array of flavours. For the most part, these notes are seen as a positive – contributing to the overall flavour profile that makes a wine taste great and pair with different foods.

However, there’s one flavour that’s usually not a positive – namely, smoke. While smoky notes might be a big plus for a peaty whisky, vineyards and grapes that are exposed to smoke produce some pretty undesirable results.

That’s led to more winemakers turning to laboratories to check whether their fruit has been affected by nearby smoke.

How are vineyards smoked?

Anyone who knows their drinks will be aware that some whiskies are smoked by peat, which was traditionally burned as a fuel to heat distilleries’ kilns. Originally a by-product of the whisky-making process, the peaty flavour is now maintained intentionally by some Scottish regions.

In stark contrast, the smoky flavour of wine is usually unintentional. While some winemakers will char their barrels to add a subtle smoky note, the smoke which blights vineyard and grapes comes from wildfires. That may not have been a problem in decades gone by, when wildfires were a rarity. However, with global temperatures rising – and extreme heat more commonplace – scientists have expressed their concern that wildfires are becoming “more frequent, more intense and more widespread.”

Understandably, that’s a problem for winemakers, whose wines can practically be ruined by the smoke exposure. The phenomenon is known as “smoke-taint”, and can lead to smoky, burnt and ashy flavours.

Identifying smoke taint

There are a wide range of readily available tests that allow winemakers to measure levels of sugar, sulphites and pesticides in their produce. Unfortunately, none of those are any use for smoke-taint. Instead, winemakers are turning to specialist laboratories who can identify smoke-taint markers in grapes, grape juice and wine.

Analysis is performed using gas chromatography, which assesses both free and sugar-bound compounds. Put simply, sugar-bound phenols are those which usually affect the taste and smell of the wine after fermentation, while free compounds are those already present in the grapes and juice.

The use of gas chromatography to distinguish between different tastes and smells is explored further in ‘Unique Separation of Mint Essential Oils by Gas Chromatography Mass Spectrometry Using Two Different Capillary Phases: Bonded Polyethylene Glycol and a Novel Ionic Liquid Phase’.

After analysing grapes, winemakers can be given a prediction for the quality of the wine they would produce – and how much smoke-taint can be expected. This allows them to make a decision on whether or not they want to proceed with production or cut their losses by scrapping their yield.