Acetobacter
Translations for „Acetobacter“
Name (lat. acetum = vinegar; bacterium = rods) for a genus of acetic acid bacteria with several species. Acetobacter can oxidise alcohol (ethanol) to acetic acid under the influence of oxygen. They are viable even at high acidity levels in wine. As they can only exist in the presence of oxygen - i.e. not in an anaerobic environment (without oxygen) - they are considered to be obligate aerobes. Ideal conditions for their proliferation are warm temperatures between 30 and 40 °Celsius, high pH values (low acidity) and an aerobic environment. Acetobacter are used industrially for the production of acetic acid and vinegar.
https://www.sciencedirect.com/science/article/abs/pii/S016816050700685X
AI Overview
Correcting high levels of ethyl acetate (which smells like nail polish remover, glue, or varnish) in wine is difficult, as it is an ester formed from acetic acid (vinegar) and ethanol. Once this fault is present, the options for remediation are limited and mostly focus on blending or advanced filtration
.Here are the methods to treat and manage ethyl acetate in wine, ordered by effectiveness:
1. Curative Treatments (Post-Fermentation)
- Reverse Osmosis (RO) / Nanofiltration: This is the most effective commercial method to remove high volatile acidity (VA) and associated ethyl acetate. The wine is passed through a filter that separates the wine into water/ethanol and components like ethyl acetate, which are then treated or removed.
- Blending: If the ethyl acetate is just above the sensory threshold, blending the affected wine with a clean, low-VA wine can dilute it to acceptable levels.
- Warning: Before blending, it is highly recommended to sterile filter the contaminated wine (using 0.45-micron filtration) to prevent the bacteria from spreading to the good wine.
- Refermentation (for Low-Level Contamination): A slight, active fermentation can sometimes help mask or reduce small amounts of ethyl acetate. This can be done by blending the affected wine with 5-6% fresh juice/must.
2. Preventive Treatments (During & After Fermentation)
- Increase SO2 Levels: Adding sulfur dioxide (SO2) immediately, or ensuring it is above 30 mg/L free SO2, inhibits Acetobacter and other spoilage bacteria that produce the acetic acid that later converts to ethyl acetate.
- Strict Oxygen Management: Acetobacter needs oxygen to thrive. Keep tanks and barrels filled to the top (properly topped up) to eliminate headspace where bacteria grow.
- Sanitization: Ensure all winery equipment, particularly barrels that have housed high-VA wines, are heavily cleaned and sanitized, as Acetobacter can live on equipment.
- Cold Stabilization: Keeping the wine cold (around 55°F / 13°C) during aging helps slow down the chemical processes that form esterification.
Summary of Options
| Intensity | Treatment Method |
|---|---|
| High | Reverse Osmosis (Specialized equipment needed) |
| Medium | Sterile Filter + Blending with sound wine |
| Low | Refermentation (5-6% new juice) |
Note: In cases of severe contamination, such as a strong, undrinkable nail-polish smell, the wine is likely irreparable and should be discarded to prevent contamination of other barrels.
