How would you feel if you got to sample the oldest Champagne to ever have been tasted? Or even, to do a full analysis of the wines to understand how they were made and how they had evolved?
You can just imagine how excited Philippe Jeandet, a researcher at Université de Reims, in France’s Champagne region, felt when he and a group of other wine chemistry specialists got to take a close look at the contents of Champagne bottles that had sunk to the bottom of the Baltic Sea in the 19th century. These very sweet sparkling wines, compared with modern standards, were headed to either the Russian imperial court or perhaps to Germany in the early 1840s, when the ships carrying them sank. The bottles then spent a very long time in a very cold and dark place until they were brought back to the surface in 2011.
The bottles were unique because of their age, of course, but also because of the context in which they had aged—very different from any cellar you could think of. What could they reveal about how wine was made two centuries ago—or about the mechanics of wine aging? This was a rare opportunity for “archaeochemistry,” which allows modern techniques to be applied to ancient samples.
Jeandet and his collaborators only got a few drops of the precious old nectar to work with (“The samples were 1.5 mL each,” says Jeandet), but it was enough to test for a wide range of chemical compounds and to find out about the winemaking, as well as the evolution of the wine.
Some bottles had been contaminated by seawater, but the ones that Jeandet analyzed further did not present a particularly noticeable level of sodium, showing that they were intact. Tasters also had noted that there was still a bit of fizziness in the wines—more than in a modern still wine.
Unsurprisingly, if you think of the environment in which the wine spent decades upon decades, the wines showed reductive notes. In sensory tests, that’s pretty much all that showed, right after opening. “The first impression wasn’t terribly good. Methane thiol, DMS, H2S: lots of reductive compounds, which may not be surprising, since the wine was in an atmosphere with very low dissolved oxygen. At 50 meters deep, there is still some, but much less than at the surface.”
In such a context, the oxidative reactions that preside over wine aging at the surface were significantly slowed down. The low temperatures—2 to 4 degrees Celsius (36 to 40 degrees Fahrenheit), compared to 10 to 12 degrees Celsius (50 to 55 degrees Fahrenheit) in a normal Champagne cellar—further slowed down reactions, meaning a very different aging (or, one would be tempted to say, lack thereof).
Opening the wines turned that context around quickly, however, says Jeandet. “After swirling the wines in the glass, the tasters who did the sensory side of the analysis started finding the aromas of a normal wine: fruity, floral, with a bit of oaky notes. There were also some tobacco and spice notes—which were a little harder to explain.” Jeandet surmises that there might be something about the extreme conditions that sent the aromatic signature of the wines in an unusual direction.
The team’s wide ranging analysis (which is detailed here) also allowed them to establish chemically that the wines had been aged in oak, as the wines showed various lactones, aromatic compounds that are derived from the wood itself. Ethyl esters from fatty acids, mainly responsible for the fruity aromas in white wines, were present as well, confirming the impressions of the tasters.
They also were able to conclude that the Champagne producers from the first half of the 19th century had developed some interesting techniques. Notably, they heated up and concentrated grape juice that was then added to the wines at the last moment to provide the high level of residual sugar (between 150g/L to a whopping 300g/L) required by their customers around the Baltic Sea.
Still, cheesy notes revealed a particular technical issue. “There was also a fair bit of malic acid, and indications that some malolactic fermentation had taken place in bottle, which isn’t surprising since it hasn’t been very long since malolactic fermentation has been fully controlled in Champagne.”
That aside, the wines were generally very sound, even in the absence of modern enological practices and approaches. “The wines showed that the producers were able to create well-made wines, at the time. For instance, volatile acidity showed at 0.54g/L, which is well below detectable thresholds.” In other words, the wines were pretty clean and sound—something the vignerons of then, as those of today, might well have celebrated by raising a lovely glass of Champagne.