Forest fires in Valais: so smoke can also be dangerous for grapes

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With a vineyard area of ​​around 4800 hectares, Valais is Switzerland’s largest viticulture canton. The currently devastating wildfires at Bitsch VS pose a threat not only to humans and animals, but also to plants. As the grape example shows, there is danger when fires are miles away.

The aroma compounds blown by the wind in the smoke can be absorbed by the grapes. However, when tasting dirty grapes, a smoky flavor is rarely observed, as the responsible flavor compounds often bind to the sugars in the grapes, forming odorless flavor compounds. The bad surprise comes later.

Smoky taste after fermentation

In the process of alcoholic fermentation, in which yeast converts sugar into alcohol, initially odorless smoky substances suddenly become perceptible. But that’s not all: As the wine matures, even more smoky flavors can emerge. Such wines then not only smell smoky, but also sometimes like plastic.

Therefore, affected winegrowers should have their grape samples tested for smoke contamination shortly before harvest. If there is a possibility of a slightly earlier grape harvest, this should also be taken into account. If the grapes are still contaminated with smoke, there are several methods to reduce the negative effects on the taste of the wine.

For example, grapes can be heated to 90 degrees Celsius for a short time and then cooled again in a vacuum. Affected wine growers may also consider lower fermentation temperatures and particularly light pressing, or mix contaminated wines with smoke-donated wines.

Source : Blick