he engine that drives grape juice to become wine is the same one that puts holes in your Swiss cheese and makes your dough rise… It’s yeast (lievito in Italian), and it’s alive. Anyone who’s heard of Louis Pasteur knows that yeast is bacteria and bacteria is alive. And like any living thing, yeast eventually dies. Even with the hard work of fermentation being finished, yeast, even though its dead, still plays an important role in winemaking.
What I’m talking about is a process called yeast autolysis, which is just a fancy term for decomposition. Yeast cells have a wonderful time processing sugar into alcohol (and CO2), and reproducing like crazy. Then, the party’s over and everyone starts dying off. Their lifeless, little, one-celled bodies sink to the bottom of the vessel and eventually decompose from the inside (a complicated enzymatic process) and the cells POP. That’s right. Pop.
These dead cells on the bottom of the vessel are actually good for wine, especially white wine, and the more contact you have (to a limit) the better your wine will probably be.
Martin is up there doing his weekly batonage (or batonnage, if you’re seriously French). Baton, like English, is French for rod, or pole, or stick (like baton-twirler), and it refers to the thing you use to stir up the lees, which is a scientific and PC term for “dead yeast and the stuff that pops out of ’em.”
There are a number of things that the lees do:
They impart a bready, yeasty aroma and flavor to wine. Champagne is a classic example. Autolysis is pronounced in champagne because the lees are kept in a small container (the bottle) and impart that beautiful bread-dough and toast aromas that makes Champagne so wonderful.
Time on the lees (sur lie, if you’re following along in French), also imparts a textural creaminess to the wine.
Substances found in the lees have an anti-oxidizing, and therefore protective, effect (especially on white wine). This allows for a more stable product that’s better suited to aging.
Batonage increases the contact and absorption of these beneficial substances. In wood, it has the added effect of lightly coating the inside of the barrel, moderating the absorption of flavor components from the oak. (In essence, a clean, filtered wine put into barrel will take up more oakiness than a dirty, leesy one.)
All of our wines spend as much time on the lees as is possible. Daily tasting is necessary to assure that the decomposition process isn’t going too far and producing off-aromas that will ruin the wine.
That’s Emilio delMedico, our enologist, and Dennis Lepore, our Commercial director, checking the health of barrels of Sauvignon and Chardonnay for ’08 Vespa. If there’s a hint of off-aromas, the batonage is stopped and the wine is racked off of the lees. Racking (travaso in Italian)is a fancy term for simply transferring the wine into another (clean) container and leaving the lees behind, which are then removed from the container and sent for distillation. The container is then cleaned and used for the next racking.
So, don’t worry if something has decomposed in your wine. It’s good!