Flaws and Faults in Wine

By George Gibson and Mike Farkas

An article for competition wine judges and of interest to competitors

A significant percentage of amateur wines in competitions exhibits “off-characters” due to lack of experience, carelessness, shortcuts, or factors beyond the winemaker’s control. Judges bear responsibility for identifying problems constructively rather than dismissing wines without explanation.

Terminology of Wine Problems

Flaws are “minor departure from an acceptable norm” that make wine atypical but typically drinkable. These should not automatically disqualify wines from scoring.

Faults represent “major departure from an acceptable norm” that spoil wines, making them significantly atypical and often undrinkable. Undrinkable faulty wines must score below 10 points.

Common Flaws and Faults

1. Reduced Sulphur Compounds (hydrogen sulfide, ethyl mercaptan, disulphides) — Often detectable via the “penny test” using pre-1986 Canadian coins
2. Acetaldehyde — Straw-like, sherry-like character from oxidation
3. MLF in Bottled Wines — Musty, stale dishcloth aromas from malolactic bacteria activity
4. Yeast Fermentation in Bottled Wine — Yeasty, effervescent character from residual sugar and viable yeast
5. Ethyl Acetate — Nail polish remover aroma from grape contamination
6. Inadequate Settling of White Juices — Leafy, vegetal, cigar-like character
7. Tyrene (TCA) — Musty, moldy wood character from cork contamination
8. Geranium Character — Geranium leaf aroma from sorbate interaction with malolactic bacteria
9. Candida-Acetaldehyde — Surface yeast producing dirty, straw-like character
10. Volatile Acidity — Vinegary character from acetic acid bacteria
11. Diacetyl — Buttery or rancid butter notes from malolactic fermentation
12. Brettanomyces Contamination — Mousy, horsey, barnyard character adding complexity at low levels
13. Chemical Contaminants — Plastics, chlorine, or hydrocarbon contamination
14. Additive Overuse — Excessive sulfur dioxide or potassium sorbate

Judging Recommendations

• Identify problems specifically rather than using vague terminology
• Provide constructive feedback indicating prevention and correction strategies
• Leave unpleasant wines for later in judging sessions
• Recognize that some compounds near threshold levels may add complexity rather than detract

Summary Classification

Usually flaws: SO₂, volatile acidity, Brett, diacetyl, sorbate, low-level reduced sulfur compounds

Usually faults: Acetaldehyde, ethyl acetate, TCA, geranium character, obvious reduced sulfur compounds