You open a carboy and vinegar hits your nose. Your wine has turned. Is it salvageable? Probably not—but understanding what went wrong helps prevent it from happening again.
What Creates Vinegar
Acetobacter bacteria convert alcohol to acetic acid (vinegar). They are ubiquitous in the environment but need two things to thrive:
- Oxygen: Acetobacter are aerobic—they require oxygen to function
- Access: They need to reach your wine
Wine that stays properly sealed and topped up rarely turns to vinegar. Wine exposed to air with inadequate sulfite protection is vulnerable.
Signs of Acetification
Early stages:
- Slight sharpness or sourness beyond normal acidity
- Faint nail polish remover smell (ethyl acetate)
- Film forming on wine surface
Advanced stages:
- Obvious vinegar smell
- Thick, gelatinous “mother” forming
- Undrinkably sour taste
Can You Save It?
Early detection (slight VA): If volatile acidity is low (under 0.8 g/L), the wine may still be drinkable. Rack off any film, add sulfites, and seal tightly. The wine will not improve but may stabilize.
Moderate damage: Wine with obvious vinegar character is compromised. You can try blending small amounts into healthier wine (if VA stays below legal limits), but this dilutes quality.
Severe damage: If it smells and tastes like vinegar, it is vinegar. No amount of treatment will reverse it. Accept the loss and learn from it.
What Went Wrong
Examine your process to identify the failure point:
Excessive headspace: Air above wine in carboys provides oxygen for acetobacter. Always top up vessels.
Loose or failed airlock: Dried-out airlocks let air in. Check water levels regularly.
Insufficient sulfites: SO2 inhibits acetobacter. Wine without adequate sulfite protection is vulnerable.
Poor sanitation: Acetobacter live on equipment surfaces. Sanitize everything.
Fruit fly contamination: Fruit flies carry acetobacter on their bodies. Keep fermenters covered.
Prevention Protocol
- Minimize air exposure at all times
- Keep vessels topped up or use inert gas to fill headspace
- Maintain appropriate free SO2 (25-40 ppm)
- Check airlocks weekly—keep water levels adequate
- Use fruit fly traps around fermentation areas
- Sanitize all equipment before every use
Making Actual Vinegar
If wine is truly lost, consider intentionally finishing the conversion to vinegar. Remove sulfites (they inhibit acetobacter), add a vinegar mother, and leave exposed to air. In a few months, you will have homemade wine vinegar—not a total loss.
