Volatile Organics: Preserving Wine Is NOT Just About The Oxygen

This blog post — Volatilizing esters brings you so much more enjoyment — reminded me this morning of a key way that the Coravin gets things right. It’s not just that it has a cool serpent’s tooth needle to pierce the cork or that it uses argon to shield the wine from oxidation.

A huge factor is that it also introduces just enough pressure to keep a variety of volatile organics like esters, aldehydes, ketones and some of the organic acids from coming out of solution.

How do they come out of the wine? Well, like alcohol many compounds can vaporize at a temperature that’s lower than water which is most of the wine. Just let the wine sit and it loses those “high notes.”

Precision bottling lines manage to keep basically one atmosphere’s worth of pressure in the ullage. A small amount of oxygen is present in the space between the wine and the cork and makes no real difference.

Some of the volatile organics will start to come out of solution, but will reach an equilibrium in the ullage when the vapor creates a counter-pressure to keep the rest in.

But the failure to pressurize the remaining wine is why most preservation systems … even those using argon or other non-oxidizing gases — will fail to keep the wine “fresh.”

I have wasted a lot of money on most of those and they have all failed because the fruit is the first to go. And that is all about pressure and volatile organics.

A NOTE: The Air Cork has the right idea. But when inflated, the membrane becomes porous enough to allow volatile organics to diffuse through. In addition, after a dozen or so uses, the porosity increased to the point that it would not maintain inflation. There is also the issue of various chemicals of emerging concern that leach out of plastics.

Further Reading

• Wine flavor: chemistry in a glass (premium)