originally posted by Jeff Brinkman:
originally posted by SFJoe:
I don't think the pH in my Sancerre was high enough to titrate pigments blue. Also, I had a notion there weren't many anthocyanins in white wine, pace Nigel above.
I don't either, that's why I mentioned the pH shift. I don't know what else would cause the blue color. I've never seen a good indication of what happens when the bottom of the cork turns blue and why it's related to premox. There are colored phenolic compounds in white wines that could color shift. But I'm still stuck on what the blue color means. Most chemists tend to believe that the short half-life of peroxide diminishes the role it plays in actively oxidizing wines. It may weaken the cell walls of the cork, rendering it unable to seal as well, but that doesn't explain the blue cork.
So my reason for posting about this wine is that it's a pretty well-controlled anecdote. Pascal Cotat did not change his winemaking in this period. I was in the cellars a couple of years later, and his barrels look older than I do. The questions about changes in practice in Burgundy really don't apply.
But what is it about the corks that is causing it? Couldn't it be something as of yet undiscovered? I still think the problem is multivariate. Do you happen to know what kind of cork he's using? It would be interesting to see what would happen if he went to unbleached/diam/etc.
Most of what I've seen as far as research goes these days is being linked to oxidation of the must after pressing but before SO2 addition. But it isn't clear that it's a smoking gun either. I guess my point is that there isn't enough known at this point to be dogmatic about what it is.
