Wine turns, or spoils, primarily due to oxidation and the activity of certain bacteria, leading to the production of acetic acid, the main component of vinegar.
The Oxidation Process
When wine is exposed to oxygen, a chemical reaction occurs between the oxygen molecules and the alcohol (ethanol) in the wine. This reaction creates acetaldehyde, which further reacts to form acetic acid and ethyl acetate. Ethyl acetate contributes to a vinegary or solvent-like aroma.
Acetobacter Bacteria
The presence of Acetobacter bacteria accelerates the process of wine turning to vinegar. These bacteria are naturally present in the environment and thrive in oxygen-rich conditions. They consume alcohol and convert it into acetic acid.
Preventing Wine from Turning
Minimizing oxygen exposure is crucial to prevent wine from turning. Here are key strategies:
- Proper Storage: Store wine bottles horizontally to keep the cork moist and prevent air from entering.
- Resealing Opened Bottles: Use a wine stopper or vacuum pump to remove air from opened bottles and reseal them tightly.
- Temperature Control: Store wine at a consistent, cool temperature (around 55-65°F or 13-18°C) to slow down chemical reactions.
- Sulfites: Sulfites are added to wine as a preservative and antioxidant. They help to inhibit the growth of Acetobacter and prevent oxidation.
Signs of Turned Wine
- Vinegary Aroma: A sharp, vinegary smell is a telltale sign.
- Acetone or Nail Polish Remover Scent: This indicates the presence of ethyl acetate.
- Dull Color: Red wines may turn brownish, while white wines may darken.
- Loss of Fruit Flavors: The wine may taste flat, lacking its original character.
In summary, wine turns due to a combination of oxidation and bacterial activity, both of which result in the production of acetic acid. Preventing this spoilage requires careful storage practices and minimizing exposure to oxygen.
