(NomaCork) - There are a number of complementary factors – and perhaps almost as many competing theories – about what makes a red wine resistant to oxygen, meaning how well and how long it will keep its aromatic profile after the bottle is opened, or how long it will keep when it is laid down in the cellar. While there is no magic bullet or single determining factor, certain elements are seen as more important than others, notably acidity and phenolics.

Since aging wine is essentially a process of slow oxidation, it seems important to make sure all the necessary elements are present in sufficient amounts to slow down that process as much as possible – at least, when trying to make a vin de garde, made for longer-term aging. However, what are sufficient amounts of these components and how do they interplay? The answers are quite complex, and there are examples that defy expectations.

For instance, it could be assumed that a lower pH and higher acidity would be an indispensable element in ensuring that a wine can age for many years if not decades. But some wines run contrary to that expectation.

“Take the 1947 Cheval Blanc, for instance”, points out Jean Hoefliger, winemaker at Alpha Omega in Napa and Monteverro, in Tuscany, who has also made wine in Bordeaux and in his native Switzerland. “It’s from a very hot year, the pH is somewhere around 3.9, so the acid is low and it was made from very ripe grapes. Yet it’s seen as one of the best ones ever made, and by all reports, it is still tasting fine to this day.”

Of course, this is a bit of reasoning through extremes: a 47 Cheval Blanc is the exception, not the rule. Not all ultra-ripe wines at a pH close to 4 will be able to keep going for over 60 years.

Hoefliger recognizes that the acidity level is an important part of a well-structured wine made for aging, generally speaking, but he argues that it may not be quite as important when other conditions are present, in a way that can compensate for lower acid. “Alcohol levels and especially tannins play a very big role as well. In Napa, I don’t need acidity in the wines in the same way that I did in Switzerland, for instance, because I have these enormous tannin structures.”