The Influence of Dosage and Cellaring Potential

RE: dosage and cellaring potential? Question possed by the International Guild of Sommeliers

Replied by Tom Stevenson

Kindly shared by Miguel Chan, South Arfica

“Patrick asked me to “wade in”, so here I am. First, I’ll comment on Pamela’s post: “I’ve tasted plenty of 10 year old non-dosage champagnes that taste wonderfully.” Good points, but I’m assuming that your 10 year old non-dosage Champagnes were literally that and not Champagnes that had undergone 10 years post-disgorgement ageing because I have never tasted a Champagne with 10 years post-disgorgement ageing that hasn’t been chock-a-block with aldehydes. If you have some, then I’m getting on a plane for Oregon straight away! On the other hand, you might like highly oxidative Champagnes and who’s to say you shouldn’t? Pamela also wrote “Isn’t it the high acid that protects against oxidation and promotes the wine to age?” Yes, indirectly acidity protects against oxidation because it affects the pH and at lower pH (higher acid) levels SO2 works more efficiently, but the difference between a totally dry high acid Riesling ageing gracefully for 40 years and a 40 year old Champagne is that the Riesling is not opened up towards the end of its life, exposed to the ai, and resealed.

The following is an enhanced version of my answer published in the current edition of Decanter magazine to a similar question about Champagnes with less than 6 grams of residual sugar:

Having tasted tens of thousands of Champagnes over more than 30 years, I am convinced that a dosage of 6 g/l is the minimum required for producers who seek graceful ageing (i.e., smoothly and with finesse) and that the lower the dosage is below this level, the more coarse and aldehydic a Champagne’s evolution will be after the oxidative impact of disgorgement. I doubt that six is a magical number; depending on the manner of production (oxidative or reductive), the style of the Champagne, grape varieties used, provenance of the grapes, the year of vintage or blend of years and numerous other variables), I’m sure there must be a certain leeway below and above 6g/l exists for specific Champagnes, but let’s keep to six as a generalisation.

This is not to say that I think all Champagnes should receive a dosage of at least 6g/l. As Patrick has correctly quoted me “Every champagne has a particular point of balance, an optimal level of dosage at which the wine feels at its most harmonious and complete. That point is different for all champagnes, depending on the character of the base material: some wines will achieve a balance at ten grams per litre, others at six, a few at three. There are even some champagnes that are sufficiently balanced and complete without any dosage at all, although this is much more rare than many people would like to believe.” But even the best of these low/no dosage are Champagnes that should be consumed, not cellared.

This view of mine is based on an overwhelming amount of empirical evidence, but while this might be good enough for the person at the centre of that experience, I accept, of course, that this is not pure science and others have every right to question it. Indeed, I want to know scientifically whether I am right and, if I am, I want to know what the mechanism is that protects a Champagne with a certain minimum residual-sugar to age without a build-up of aldehydic aromas in its post-disgorgement phase. When I try to think about it rationally, I immediately dismiss the widely held misbelief that sugar has any preservative quality because, at concentrations found in Champagne, it really has none at all. Sugars have several alcohol or hydroxyl groups that could, I suppose, react with the carbonyl group of acetaldehyde, and sugars can react with amino acids, potentially forming heterocycle compounds, which could also bind acetaldehyde, but do these things happen in champagne? I tried searching for papers published about the effect of dosage on the ageing potential of Champagne, but came up empty-handed, which is why, in 2008, after witnessing an alarming increase in the number of low/no dosage Champagnes, I asked Bertrand Robillard, the world’s foremost expert on the chemistry of Champagne, whether sugar could mask aldehydic aromas. He told me: “A lot of people who make a low-dosage or no-dosage Champagne do not add SO2 at the time of disgorgement, and these wines show a high oxydability level. [And yes,] sugar is a good compound for screening some aromas.” When I asked him to elaborate on his last sentence, he confessed, “I’ve never read of any experiments on the influence of sugar on aromas [in Champagne], but I have noticed this effect. I know that some people consider this to be a fact, and we can imagine that some aldehydes could be sensitive to this phenomenon.” It was reassuring to know that Robillard’s lifetime experience had led him to a similar conclusion, but although it is amusing to hear a scientist rely on empirical evidence, it also illustrates a huge gap in Champagne’ scientific knowledge.

Some Champagne producers have gone the low-no dosage route for stylistic reasons and some would prefer to describe this strategy as more natural. However, with lower acidity and disproportionately higher pH levels due to warmer, shorter growing seasons (it is the first time in history that Champagne has experienced three August harvests within the same decade), there has been a large influx of such Champagnes onto the market from producers whose knee-jerk reaction was simply to reduce the dosage. There are other remedies, such as acidification or a combination of acidification with a more subtle lowering of the dosage, but if Champagne is to remain the world’s greatest sparkling wine, the only satisfactory solution will be found in the vineyards, primarily through different clonal selections and, maybe, a shift of emphasis from south-facing to east and west for what slopes should be considered superior. In the meantime, however, Champagne producers are merrily lowering dosage levels based on no scientific research whatsoever and if the empirical evidence is correct they risk damaging Champagne’s reputation for longevity.

Since discussing this matter with Robillard, I have come across a paper called “Volatile Flavoring Substances in Foodstuffs” (Hans Gerhard Maier, 1970), which supports the theory that sugar suppresses acetaldehyde. While this is a useful starting point, later researches in this area have all involved sugar and viscosity levels that are not appropriate for the aroma matrix of a wine. One thing is clear, however: the Champagne industry should not be embarking on ever-lower levels of dosage without conducting its own research into the processes involved.”


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