Scientists analyze champagne from sunken cargo ship
Shipwreck champagne: Pleasant, with a low alcohol content
Divers recovered the 168 bottles of champagne from a shipwreck around 50 meters under the sea off the coast of Finland’s Åland islands. Even after 175 years, the content of bottles was clearly identifiable. “This was undoubtedly helped by the near perfect storage conditions. The bottles were kept in complete darkness at temperatures of between two and four degrees Celsius and with only a small amount of pressure and salt content,” explains Prof. Philippe Schmitt-Kopplin who investigated the sparkling wine in collaboration with Reims and Dijon universities as well as the Helmholtz Zentrum Munich and Technische Universität München.
The scientists discovered that the bottles came from the Veuve Clicquot Ponsardin, Heidsieck and Juglar (now Jacqueson) champagne houses. At the first tasting session, the champagne was dominated by unpleasant aromas due to the high proportion of phenols in the wine. Terms such as “animal notes” and “wet hair” were used to describe the taste. After a while, however, more pleasant aromas started to come through and the champagne was described as having fruity, smoky and leathery notes.
Destined for Germany?
The researchers were surprised to find that the samples they investigated were in a perfect hygienic condition, even for today’s standards. They found almost no signs of microbial decay and the chemical fingerprint was the same as modern-day champagne. The vintage champagne also opened a unique window into wine-pressing techniques used in the nineteenth century.
One of the most striking characteristics of the Baltic Sea champagne was its high sugar content. This initially led the experts to believe that it was destined for Russia, where very sweet sparkling wines containing 300 grams of sugar per liter were in vogue at that time. As it turned out, however, the vintage champagne had a comparatively low sugar content of 150 grams per liter. This would have most likely made it too tart for Russian tastes, leading experts to surmise that the bottles may have been bound for Germany.
Sweetened with grape syrup
The practice of adding sweet syrup to champagne once the yeast has been removed and before the bottles are corked is still common today. Up to 100 grams per liter can be added for sweet sparkling wines. This sweetener, known as “liqueur d’expedition”, can be made from grapes, sugar beet or sugar cane.
In the case of the champagne recovered from the wreck, the researchers identified a complex chemical profile that suggested grape juice was used as the sweetener agent. This came as a surprise, as original documents from Madame Clicquot, the owner of the eponymous company at that time, show that she had ordered large amounts of sugar cane. It is possible, however, that this cane was then used for other purposes – for example, to sweeten the must prior to fermentation.
To achieve a sugar content of 150 grams per liter, the winemakers would have had to have added a lot of grape juice. So much, in fact, that it would have brought the alcohol content significantly below 10 percent. “We therefore believe that the winemakers concentrated the grape juice and then used this syrup to sweeten the champagne – a process known as ‘dosage’ in the industry. Our analyses confirmed this. We were able to identify, for example, the presence of 5-hydroxymethylfurfural, a substance that occurs during caramelization.
Low alcohol, high metal content
At 10 percent, the alcohol content of the shipwrecked champagne was quite low. Modern day champagne, for example, contains around 12 percent alcohol. This could be due to the cooler climate at that time which would have meant that the grapes were harvested later and were not as sweet as grapes today. At that time, winemakers also used wild yeast, which did not process sugar as efficiently as modern, cultivated yeasts. The researchers believe that as a result of this, the alcoholic fermentation process was often incomplete.
The chemical analyses also revealed a high content of metal ions. The records kept by Madame Clicquot show that barrels were already sulfurized at that time to protect them from fungal pathogens. The sulfur wicks were held in iron rods which could have oxidized and released ions.
The metal ions, however, could also have entered the champagne in the taille. This is the juice obtained from the second pressing after the first, higher-quality cuvée pressing. Due to the higher proportion of grape skin, the taille has a different chemical composition of metals and metabolites. On the basis of this, the researchers believe that the winemakers used a large proportion of taille in the champagne recovered from the Baltic shipwreck.
“In addition, the pinot noir grape was a lot smaller then than it is today. The skin-to-pulp mass ratio would therefore have been a lot higher,” elaborates Schmitt-Kopplin. “This high skin percentage could also be responsible for the high metal content.”
Chemical messages in 170-year-old champagne bottles from the Baltic Sea: Revealing tastes from the past; Philippe Jeandet, Silke S. Heinzmann, Chloé Roullier-Gall, Clara Cilindre, Alissa Aron, Marie Alice Deville, Franco Moritz, Thomas Karbowiak, Dominique Demarville, Cyril Brun, Fabienne Moreau, Bernhard Michalke, Gérard Liger-Belair, Michael Witting, Marianna Lucio, Damien Steyer, Régis D. Gougeoc, and Philippe Schmitt-Kopplin; PNAS; DOI: 10.1073/pnas.1500783112
Prof. Dr. Philippe Schmitt-Kopplin
Technische Universität München
Chair of Analytical Food Chemistry
Tel.: +49 89 3187-3246
Mobil: +49 160 98967479