The chemistry of wine aging

Hi Clark. Recently got your book and it is fantastic – as a basically internet-educated wine drinker without a really deep knowledge of wine chemistry or winemaking, your first chapters on solution vs. structure are giving me a whole new conceptual language to think about wine. Thanks, and I hope you continue to hang around Wineberserkers even after your ‘guest host’ stint is over. I know a lot of us would value that.

I’ve often wondered just how well we understand and can predict a wine’s aging curve, and also what is happening chemically when a wine ‘shuts down’. From what I can tell in the book, your perspective seems to align pretty well with the traditional one, saying that there is an inverse relationship between wine aging capacity and its approachability when young. You basically seem to hypothesize a linear relationship between ‘reductive strength’ or anti-oxidative capacity and aging – a wine’s energy lies in its capacity to absorb oxygen, and the long, slow process of oxygen absorption over aging gradually softens tannins and makes the wine softer, more subtle, more complex, and more approachable.

I have several questions, pardon me if they are too elementary or are already answered somewhere in your book.

The ‘linear’ picture of wine aging doesn’t seem intuitively accurate to me. I often find long-aging wines have a period of being ‘open’, fruity, and exuberant soon after release, where there are tannins but they are buffered by the fruit. The wine may then shut down for a while, then reemerge in a somewhat different way, then shut down again, then reemerge, etc. So it is more like a sine wave than a straight trend.

How well is this process understood? How well do we actually understand the long, slow oxidation process of bottle aging and exactly what it does to the colloids in the wine? Why is there a relationship between the tannins ‘softening’ and the complexity of the wine? Why does that relationship sometimes go in reverse, when the wine ‘shuts down’ (loses complexity and expressivity for a long period) as it ages? What is actually happening inside the wine when it is ‘shut down’? How does the initial ‘open’ phase correspond with your apparent belief in the book that there is an inverse relationship between aging capacity and pleasurable drinking when young? How much do we really know about how modern techniques are impacting the bottle aging process?

I know these are probably some of the biggest questions in fine wine, so don’t expect any definitive answer, but would love to hear any insights you want to share. Thanks very much!

Well, I certainly often talk about those “awkward teenager” middle years when a Cabernet or Chenin Blanc has lost its youthful fruit and florality but has yet to develop the tertiary nuances. I actually sneak a little Viognier into my sur lees dry Chenins to get them through this phase.

I also agree that a wine can encounter a “bad patch,” and my advice is always: “Don’t drink it when it tastes bad.” Often surprising improvements can occur.

Wines with a lot of reductive strength, when newly bottled, will taste open and fruity for a few months and then clam up and even make sulfides. This is an artifact of the oxygen pickup inherent to the bottling process, particularly when natural corks are employed, because they contain compressed air which will release into the wine.

It is also commonplace for wines to experience a microbial bloom in the bottle. Those that have been kept in a 55 degree cellar all their lives are particularly prone to this as soon as they encounter room temperature storage in commerce. Often the wine will reabsorb or react away the off odors and come back together after a time.

It is essential to appreciate the importance of the environment in which a wine is tasted. Much of what is attributed to bottle variation or “bad patch” is actually the wine being served in the wrong environment, as my experiments with music clearly show.

All that said, aging chemistry is so complex that nobody really understands it. Your sine curve seems a bit to formulaic, but I do think wines are living things and like music progress through harmony and dissonance, tension and resolution throughout their lives.