(Wine-Searcher) - Scientists have made surprising discoveries as they examine wines recovered from the bottom of the Baltic Sea.

A shipment of 19th-century Champagne recovered from the ocean floor is revealing new details about centuries-old ways of making wine, and giving fresh insights into the people who drank it, scientists said Monday.

The latest analysis of some of the 168 bottles found in 2010 on the floor of the Baltic Sea shows it was three times sweeter than modern bubbly, and suggests that the cool, dark ocean might make an ideal storage cellar, said the research published in the Proceedings of the National Academy of Sciences, a peer-reviewed US journal.

"After 170 years of deep-sea aging in close-to-perfect conditions, these sleeping Champagne bottles awoke to tell us a chapter of the story of winemaking," said the study, led by French researchers.

While the labels were long gone by the time the bottles were discovered, researchers have traced them to well-known Champagne-makers Veuve Clicquot Ponsardin, Heidsieck and the now-defunct house of Juglar, based on markings on the corks. The bottles contain what is likely the oldest Champagne ever tasted.

"Possibly the most striking feature of the Baltic Champagne samples is their extraordinarily high sugar content," said the study led by Philippe Jeandet, a professor in the Faculty of Sciences at the University of Reims.

That sweetness may have come from grape syrup that was added before corking, the study said. The bottles contained about 140 grams of sugar per liter, many times the amount typically seen in modern times. Many of the major Champagne houses' brut Champagnes contain around 8-12g/L of residual sugar.

Ever since the bottles – dating from between 1825 and 1830 – were discovered deep in the Baltic Sea off the coast of Finland, many have surmised that the shipment was headed to Russia. But correspondence from the era between Madame Clicquot and her agent in Saint Petersburg shows that the Russian market had a preference for very sweet wine, containing 300 grams of sugar per liter. People there liked sweet drinks so much, it was customary for diners to add spoonfuls of sugar to their wine at the table, researchers said.

"Thus, the relatively low levels of the shipwrecked bottles, less than 150g/L, suggest that they might instead have been headed for the customers in the Germanic Confederation," said the study.

Even after nearly two centuries, the Champagne did not go bad.