Chemistry, oak and aging.
Grapes taste like, well, grapes when they come out of the vineyard. The ones used for wine are different in structure to those in the supermarket. If you ever get the chance to taste nice ripe vineyard grapes, you’ll note that the seeds are bigger, the grapes smaller and the taste a lot more concentrated.
Up until you add yeast and they ferment, they will taste just like nice sweet grapes/grape juice. Then the magic happens. The chemical structures change to build flavour compounds that are very similar to those in other materials. Simple as that. These are not added like the flavouring for yoghurt, but occur naturally by fermenting grapes.
What is added are oak related flavours. When the wine is submitted to extended contact to oak, it adds cedar, buttery, creamy, vanilla or even coffee notes to the wine among other things. You will note this difference in taste by a basic experiment:
Go out and fork out $8-10 each for a normal aussie chardonnay, and an unwooded chardonnay and taste for yourself. The wooded will be creamier, the unwooded crispier and fruitier. Then its up to you to decide.
The use of oak in its myriad of variations is a big decision for the winemaker.
Next is ageing. Good aged wines are less fruity, more savoury and are more refined with softer tannins (the stuff that dries your mouth). This is a whole topic on its own.
For a nerd fact: the flavours coming from a grape varietal are called “primary aromas”, those from the wine-making process “secondary aromas” and those from aging and oaking “tertiary aromas”.
To get an overview of typical flavours for some common grape varieties check out this guy’s cheat sheet.
- WINEDUCATION - 