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Malolactic Fermentation After Cold Stabilizing

TroubleShooting

Jim Boutin — Pownal, Vermont asks,
Q

Recently I conducted a paper chromatography test to check the status of malolactic fermentation introduced this fall into a number of 5-gallon (19-L) Marquette carboys produced from my backyard vineyard. Results showed plenty of malic acid still present. I plan to cold stabilize over the winter months in my winery. Will malolactic fermentation under these circumstances naturally kick back in when temperatures rise in the winery in the spring? Or is it best to re-inoculate with new culture and nutrients in the spring?

A
I always think it’s wonderful when people can do a “natural” cold stabilization over the winter months. It’s an incredibly intuitive and very old-fashioned, non-interventionist way to accomplish a key winemaking task. It never gets cold enough here in Napa, California during the winter to really knock down any significant amount of our tartrate crystals (the goal of cold stabilizing a wine), so that’s very cool (LOL) if you can do it. I do indeed think that it’s very likely that your malolactic fermentation will re-start once the weather warms up. Instead of re-inoculating (malolactic bacteria are expensive!) you could wait and see if you start to get any activity when the temperatures start to rise. You can do this by monitoring the disappearance of the malic acid spot on your paper chromatography test. In addition, you can also listen at the mouth of your carboys for the little “tick . . . tick . . . tick” of carbon dioxide bubbles being produced by an active malolactic fermentation. To be sure that you’re detecting any change, do a chromatography
Response by Alison Crowe.