In Ageing

At a recent Methode Cap Classique meeting I attended, one of the speakers spoke about very old champagne that was discovered in a shipwreck at the bottom of the Baltic Sea. After further investigation, I discovered that 168 bottles of champagne were resurrected. The ship itself is thought to date back to the second quarter of the 19th century, which makes this champagne very old indeed. I should also add that this wine was tasted by at least one wine pundit and received very positive tasting notes! I’ll come back to wine critics later, but let’s briefly dive into the technical pool first.

Part 1 of this blog gave some history and a brief overview on bottling and bottle variation. This installment will focus on factors influential to aging and bottle variation.

Air ingress is a function of all the factors which I will briefly touch on, so keep this in mind as you read on. Low cellar humidity is a powerful driving force for evaporation, from barrels to bottles. Some winemakers are proponents of humidity levels of up to 70% (if possible), as this lessens the gradient between the outside of the bottle and the ullage (100% humidity). Informed wine connoisseurs often prefer old bottles with damp damaged labels, as this means that the wine was probably stored in high humidity conditions. Sadly, old wines with perfect labels usually get higher prices than their counterparts with pristine labels. A constant optimal temperature is also very important when storing wine. This could possibly be the explanation why underground cellars and Davy Jones’s locker are good places to preserve wine. High cellar temperatures invariably speed up the rate of maturation chemical reactions, in conjunction with the wine expanding in the bottle. This is turn leads to compression of the headspace. This forces air, water and ethanol out of the bottle and upon cooling and contraction of the wine, air is sucked back into the headspace (you might remember from Part 1 of this blog that the cork is not sucked in again). Each of these expansion and contraction cycles introduces more air into the bottle, as there will always be more air entering the bottle than there will be leaving it. Quite nasty. There is also much uncertainty about ullage (fill level) of old wines, but I would like to at least quote Kevin Swersey of the Connoisseur’s Advisory Group: “Generally speaking, older Burgundies have more ullage than older Bordeaux. Why? I don’t know. And certainly, the old California wines have the least ullage of any wines I’ve ever seen,”  It seems to me that the Burgundophiles and the Bordeaxphiles have disparate opinions on the effect of fill level on wine maturation in their separate  regions, but I shall indeed tread very lightly here and move along quite swiftly. Another obvious cause of bottle variation can be unfiltered wine. Under optimal conditions (e.g. the presence of sugar), microbial growth could happen and the result is anybody’s guess.

Finally, there is a very interesting article on how bottle variation can affect the judging of wines. This can be found in the June 2012 issue of Wines & Vines. If you’re interested, have a look at it and let me know what you think.

Bernard Mocke is a technical consultant for Oenobrands


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