New research from France explains why:
‘What we have uncovered is that it is the species of oak that makes the greatest difference to taste. The research uncovered that oak contain naturally-occurring compounds that impart sweetness (the QTTs), and others that impart bitterness (there are several, but one of the key molecules is Glu-BA). Peduncular was richer in bitter compounds and sessile in sweet.’
Sessile oak has always been privileged for ageing wine. It contains many of the aromatic molecules such as vanillin and whisky-lactone that imparts the patisserie and coconut smells typical of oak-aged wine, but the discovery of the QTT molecules deepens our understanding of why. Taste is intensified by molecules of aroma, so a sweet taste will ‘taste’ sweeter if it is imprinted with the smell of vanilla. In this way, sessile oak wins on both counts.
If I understand this correctly, we perceive sweetness in wine that has been exposed to vanillin or whiskey lactone because we associate vanilla and coconut with sweet foods. But if we associate vanilla and coconut with sweetness because they are usually consumed with sweet foods, doesn’t a similar phenomenon occur with fruit? Ripe fruits are naturally sweet and so we are likely to taste sweetness in a fruity wine even if it is bone dry.
The mind plays tricks.