Wine Fault

Acetobacter

Microbial

Acetobacter converts ethanol into acetic acid, producing a sharp vinegar-like sourness and volatile acidity spike. The fault destroys balance and is irreversible once established at noticeable levels.

Also known as: Acetic acid bacteria, Acetic spoilage, Vinegar bacteria

Typical severity: High

Cause

Acetic acid bacteria (Acetobacter and related genera) oxidizing ethanol to acetic acid in the presence of oxygen.

How it occurs

Exposed wine surfaces, leaky barrels, poor topping, and unsanitized equipment invite Acetobacter. High pH, warm cellar temperatures, and oxidative handling accelerate growth.

Prevention

Minimize oxygen exposure, maintain SO₂, keep cellars cool, top barrels regularly, and sanitize all transfer equipment. Discard or treat affected lots before blending.

Descriptors created

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Commonly confused with

Common wine styles

Common grape varieties

Common regions

Related winemaking techniques

Serving implications

Beginner explanation

If wine smells distinctly like vinegar or salad dressing, suspect acetic spoilage — not normal tartness.

FAQ

Can acetic spoilage be fixed?
No — once Acetobacter has raised acetic acid to fault levels, the wine cannot be corrected through decanting or aeration.
How is this different from volatile acidity?
Acetobacter is one source of VA. VA measures multiple volatile acids; Acetobacter specifically drives vinegar-like acetic character.

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See also

Fault identification guidance reflects common wine education practice and may vary by wine style, age, and context.