The middle of spring brought with it a welcome milestone in our cellar: our vintage 2025 Chardonnay finished malolactic fermentation. It’s not a flashy moment in the winemaking calendar, but it’s a significant one. What happens during this process irreversibly shapes the structure of every bottle of Patz & Hall.
What Malolactic Fermentation Really Does
Every Patz & Hall wine goes through malolactic fermentation, though Chardonnay always takes longer than our Pinot Noirs to get there. That lag creates real anxiety in the cellar. Young wines can’t be protected by sulfur while they’re still going through conversion, which leaves them exposed longer to oxidation, volatile acidity, and other threats longer than we’d like them to be. Most years there are a handful of stubborn late finishers among the barrels. This year, everything cooperated on schedule.
Acids in unfermented grape juice are typically a quarter malic acid and three quarters tartaric. Traditional Chardonnay winemaking calls for the conversion of malic acid to lactic acid. The organism doing the work is the bacteria, Oenococcus oeni. Malic acid is the sharp, green-apple tartness. Lactic acid is softer, closer to what you find in dairy. The conversion rounds out the palate and adds a subtle creaminess to the texture.
Why Butter Ain’t The Goal
One byproduct of this process is diacetyl, which is the compound behind that buttered popcorn aroma you find in some Chardonnays. Some wineries actively pursue it. We do not. We seek to showcase vineyard and vintage rather than a flavor profile. If you give the bacteria time, they will metabolize the diacetyl on their own, and the butteriness fades. It’s all about patience and that old friend, intestinal fortitude.
What Comes Next
Malolactic fermentation has been complete for well over a month, and now the wines will continue aging in barrel before bottling in February 2027. We’ll keep you posted on their development.