Wine myths
Old barrels are the same as stainless steel
“After a few uses a barrel is neutral, so an old barrel is basically a steel tank.”
The extractable flavour compounds do fall away with use, but the barrel still admits oxygen and still has a large surface area. A neutral barrel is not an inert vessel.
The full answer
What declines with each use is the extractable material — vanillin, oak lactones and the toast-derived compounds are drawn out heavily in the first fill and much less thereafter. By the third or fourth use, aromatic oak contribution is small.
What does not decline is the vessel’s permeability. Oxygen continues to move through the staves and around the bung at a rate a sealed steel tank does not permit, and that slow ingress keeps changing tannin structure and colour.
The high surface-area-to-volume ratio of a barrel also keeps the wine in closer contact with its lees than a tank does.
So a winemaker choosing old barrels over steel is choosing a particular oxygen regime and a particular texture, not simply avoiding oak flavour.
The aromatic contribution really does fall off sharply with use, which is the whole reason old barrels are used for wines meant to taste of fruit rather than wood.
A biochemical or physical process that has been demonstrated experimentally and is not seriously contested — the sort of statement that appears in enology textbooks without hedging.
What would settle it: A controlled experiment failing to reproduce the process.
Sources
Sources consulted
- The Australian Wine Research Institute — AWRI
- WSET educational materials and the Systematic Approach to Tasting — Wine & Spirit Education Trust
- The Oxford Companion to Wine — Oxford University Press