Eucalyptus character in wine
Wine lovers are sometimes given a hard time for the detailed descriptors they use to describe wine. But when it comes to eucalyptus, that is exactly what we are smelling.
The Australian landscape is filled with gum trees, and they contribute to the distinctive and unique scent of our bushland. The smell is due to the volatile oils released by the leaves. And when vineyards are located near eucalyptus trees, this scent can make its way into wine.
The Australian Wine Research Institute (AWRI) has conducted extensive research into eucalyptus character in wine. The main component of eucalyptus oil is the compound 1,8-cineole. When you smell mint, eucalypt or camphor in a wine, you are probably smelling this compound.
Whether eucalypt is a desirable aroma, or not, is contentious. As with most characters in wine, a hint is often acceptable and can add to the personality and enjoyment of a wine. But when the character is overt or dominating, then it is less desirable.
I have heard some winemakers refer to eucalyptus character as part of the terroir of their wine.
What is interesting about the character is that it is very stable in wine over time. And it is normally stronger in red wines than whites due to fermentation in the presence of skins.
The work conducted by the AWRI showed that while absorption of 1,8-cineole by the grapes was a factor, the presence of eucalyptus leaves or bark in the picking bin had a major impact on the final level in the wine. As did the presence of grape vine leaves and stems which also pick up the compound.
Thus, for vineyards grown close to gum trees, the character is probably stronger in machine harvested grapes than carefully selected hand-picked fruit.
The AWRI found 1,8-cineol to be above the sensory detection threshold in many wines tested. However, it is just one of the many aroma compounds present in wine. When I trawled through my library of tasting notes, I only found it to be an overly dominating character in a few wines, and less in recent years. One expects that armed with the knowledge and production strategies provided by the AWRI, winemakers now have more understanding and control over the level of eucalyptus character in their wines.