Toasting Louis Pasteur

ARBOIS, France — The region of Jura is known — if at all — for its green, rolling hills and as a source for the firm, delectable cheese called Comté. But as you drive into Jura, you see official road signs describing Jura as the "Pays de Pasteur," the land of Louis Pasteur. Indeed, Pasteur is why I went to Arbois. It is a town of 3,698 people, nearly all of whom seem dedicated to eating Jura's traditional, rather heavy, and utterly delicious food, and drinking the peculiar, sherry-like dry white wine called vin jaune, or yellow wine. Not in the least, they also celebrate the home of Pasteur, who was Arbois's most famous citizen.

It was here that Pasteur spent his summers, receiving visitors who sought to steer his probing mind to their particular problems. Indeed, Pasteur single-handedly solved a potentially catastrophic problem for the industry; he became the father of microbiology, and, most famously, Pasteur created and courageously demonstrated a vaccine for rabies.

But he also solved one of the longest-standing mysteries of civilization: the cause of fermentation. "Louis Pasteur was the father of enology," declared the tour guide who showed us through Pasteur's stuffily decorated, bourgeois home in Arbois, which was also a former tannery along a river. It was an accurate statement. Everything that's technically good about wine today, we can trace to Pasteur.

His home contains his only surviving, intact laboratory. When you see it,

you're almost shocked at its simplicity, although it was well equipped for its mid-19th-century day, with piped-in gas and a special warming room where Pasteur could incubate his microbial cultures. Compared to today's high-tech tangle of equipment, it's hard to believe that a laboratory such as this was where some of science's thorniest practical problems were solved.

Today, we seem to have forgotten Pasteur. His name, if recognized at all, is associated with milk. But the process called pasteurization was, in fact, originally intended for wine. Pasteurization, though, has long since been rejected in wine-making in favor of other methods of microbial stabilization, such as filtration.

In the world of wine today, everything we know about contemporary wine-making — controlled-temperature fermentation, filtration, the effect of oxygen on wine — derives from Pasteur's penetrating inquiries.

Pasteur's single greatest achievement is possibly his proof that life — not decay or spontaneous generation — causes fermentation. It was a trial-and-error mystery for millennia until 1857, when Pasteur first read his paper called "Memoir on Lactic Fermentation" to the Scientific Society of Lille. It was not received with huzzahs. Pasteur was a provincial chemist who had not attended the great scientific universities in Paris or Germany. He was seen as an upstart rube that dared to contradict the greatest scientific minds of his day.

The great French chemist, Antoine Laurent Lavoisier, postulated that alcoholic fermentation was a chemical matter, specifically a chemical splitting of the sugar molecule. This notion that the cause was chemical, rather than a life force (yeasts), was popular and widely held.

Justus von Leibig, a German chemist who was the towering figure in his field, insisted that fermentation was a function of decay. According to von Leibig, the yeasts died and their rotting caused fermentation. Unfortunately for Pasteur, von Leibig lived until 1873 and clutched his theory to the end. By then, Pasteur had long since proved it wrong, but von Leibig's prestige and aggressive opposition didn't help matters any.

In 1859 Pasteur presented his landmark "Note on Alcoholic Fermentation." In a feat of imaginative laboratory demonstration, he showed how yeasts would grow and reproduce — and cause a fermentation — on a medium that could not putrefy. Von Leibig refused to accept the evidence. From there, Pasteur went on to prove (again through simple but rigorous laboratory demonstrations) that oxygen not only degraded wine, but that air itself carried yeasts and microbes that could contaminate wine and make it go bad. Flash heating was Pasteur's effective solution. To this day, a few wine producers continue to employ the technique to stabilize their wines.

And what about the wines of Pasteur's beloved Jura? Fittingly, Pasteur's own vineyard is still cultivated. A famous local producer, Henri Maire, makes a red, white, and rosé Cuvée Louis Pasteur from Pasteur's original vineyard. The wines are good, but, alas, nowhere near as great as the vineyard's original legendary owner.