Smoke taint occurs when aroma compounds in smoke are absorbed directly by grapes. The grapevine responds to these foreign compounds by linking sugar molecules to them, in a process called glycosylation. Glycosylation.  Once the smoke aromas (volatile phenols) are linked to a sugar molecule, they can’t be smelt or tasted and are described as ‘inactive’. They also stay mainly in the grape skin.

However, during winemaking the volatile phenols can be released, converting them back to their active form in the wine which can be smelt or tasted. This can give (largely undesirable) flavours to the wine including ‘burnt, ‘disinfectant’, or ‘ashy’, and we refer to this wine as ‘smoke tainted’.

Volatile phenols can also be released in the mouth when the wine is tasted, exaggerating any smoky flavours. The glycosylated precursors therefore essentially act as a pool of smoky compounds waiting to be released. 

Studies show that most consumers do not like smoke-affected wine, and even a small proportion of smoke-tainted wine in a blend can be noticeable. The acceptance of smoke taint has been tested across a range of grape varieties, and the number of consumers who appreciate the experience varies, depending on the natural base level of ‘smoky’ characteristics in the grape variety, the degree of smokiness and the wine style. The perception of smoke characters also varies widely between individuals, and smoke taint can easily be confused with other characters, for example if the wine is made with oak, especially toasted oak. 

However, we do know that if a trained and experienced winemaker can spot the smoke taint in a sample, it’s highly likely that the end-drinker will too.