Ask Wine Wizard

Cucumber Wine

TroubleShooting

Lee — via email asks,
Q

Just for fun, I made a vegetable wine out of cucumbers. My problem now is that the specific gravity is at 0.990, but the “must” is still actively bubbling in a carboy . . . like a bubble every 5 seconds. It tastes dry as well. I’ve NEVER seen this happen before, with the hundreds of grape wines that I’ve made. Would there be that much dissolved CO2? Should I just rack and vigorously stir the wine?

A
Well, according to specific gravity, your cucumber wine (sounds refreshing) is dry. For RS-dry (residual sugar dry) you want to look for an SG of 0.992 and 0.996 on your hydrometer. If your wine is dry, with no sugar left to ferment, and it’s still actively producing CO2, then the next thing I’d wonder about is this: Is there another microbe in there eating something and producing CO2? Since I’m not too familiar with the chemical makeup of cucumbers, I did a little quick research and lo and behold, it turns out cucumbers are chock full of malic acid. And what common wine microbe eats malic acid and pumps out carbon dioxide gas? How about your friend and mine, malolactic bacteria? These guys are often purposely inoculated into wines for this specific purpose — to render wines more microbially-stable during storage and bottling, as well as to naturally de-acidify them. Typical of these bacteria are Oenococcus oeni and various species of Lactobacillus and Pediococcus. If I had to put money on it I’d wager you’ve got a spontaneous secondary fermentation
Response by Alison Crowe.