Barrel Samples

Gerald, The estimable Prof. Emile Peynaud offered an explanation for that phenomenon in his book "The Taste of Wine." He notes that the bitterness/astrigency of tannins changes as a function of their size. If one were to graph their bitterness as a function of size, what you'd see is that small sized tannins are relatively non-astringent, but as they increase in size (as they inevitably do as they age and/or get exposed to oxygen) they become *very* astringent, but further on become increasingly softer and less bitter -- until at a large enough size they become insoluble at fall out as sediment. So, at the point of barrel samples, most red wines still have small, softer tannnins. I would presume that most winemakers have a good sense of when their barrel samples begin to toughen up and probably stop offering tastes of them to the public. By the time they make it into bottles, they're usually close to that maximum astringency, which then begins its slow decline as the wine ages. We usually think of exposure of a wine in its youth to oxygen as a softening process (white wines become "rounder," micro-oxygenated reds become softer) but in truth the tannins will become harder before they soften, as they inevitably must. The exposure to oxygen just accelerates this process.

Mark Lipton

The slow ingress of oxygen softens the wine in barrel, but just before bottling the winemaker often steps in and fines the wine (and sometimes filters as well) to tame aggressive tannins and "polish" the wine a bit so as to make it more approachable. That's a big part of the art of winemaking.

Tom S