Whether you’re a beginning wine lover or someone who has been tasting passionately for years, nothing is more disappointing than opening a bottle that smells musty, tastes strange, or simply feels “not right.” Wine faults occur more often than you might think — even wines from renowned producers can suffer from them.
Is there good news? Absolutely. With just a little knowledge, you can learn to recognize wine faults and avoid pouring a glass filled with cork taint, oxidation or brett.
In this article, we dive into the world of the most common wine faults. You’ll learn how they develop, how to identify them, and, perhaps even more importantly, what you can do when you encounter them. Because every wine fault is one too many.
Cork Taint: The Most Famous (and Most Misunderstood) Wine Fault
The term “cork” is familiar to most wine drinkers. Many people assume it refers to pieces of cork floating in the glass; but that is not what cork taint actually is. So what do we mean?
What Is Cork Taint (TCA)?
Cork taint is caused by TCA (2,4,6-trichloroanisole), a chemical compound formed when natural cork interacts with mold and chlorine compounds.
How to Recognize Cork Taint
• Musty smell: wet cardboard or damp basement
• Muted flavors and aromas
• Red wines lose fruit, liveliness and complexity
How Common Is It?
About 2–3% of wines sealed with natural cork contain detectable TCA. Screw caps reduce, but do not eliminate, the risk.
Oxidation: When Wine Gets Too Much Oxygen
Oxidation is one of the most common wine faults, and often the most disappointing. When wine is exposed to too much oxygen for too long, undesirable changes occur.
How to Recognize Oxidation?
• White wine turns dark yellow/brown, red wine loses depth
• Flat, dull or vinegar-like taste
• Nutty or sherry-like aromas when unintended
Causes of Oxidation
• Poor seal (damaged cork)
• Improper storage
• Wine kept open too long
• Low-sulphite winemaking
Brett: A Smell You Won’t Forget
Brett, or Brettanomyces, is a yeast species that causes considerable division among wine enthusiasts. Some call it “complexity,” others “contamination.”
What Is Brett?
Brettanomyces is a wild yeast that can live in cellars, barrels or bottles.
How to recognize Brett:
• Aromas of barnyard, stable, leather, sweat or wet dog
• Bitter, medicinal or sharp flavors
• Less fruit and a rough finish
Is Brett a Fault?
Yes, when concentrations are high. Some winemakers intentionally use it, but generally it indicates poor hygiene or cellar control.
Other Common Wine Faults
Besides cork, oxidation, and brett, there are other wine faults that any serious wine lover should be able to recognize:
1. Sulphur: Too Much Sulfite Ruins the Experience
Sulfite, or sulfur dioxide, is added to wine to protect it from oxidation and spoilage. However, excessive sulphur can itself create a wine fault. How do you recognize it? By a sharp, irritating smell reminiscent of struck matches or rotten eggs. The wine may smell chemical and can even cause headaches. Maintaining the right balance of sulphite is essential. The Amsterdam Wine Academy teaches you how to detect and evaluate sulphite in wine.
2. Volatile Acidity: When Acetic Acid Appears in the Wine
When acetic acid bacteria or unwanted yeasts become active, volatile acidity develops. This is often the result of poor storage conditions or inadequate hygiene. It is recognized by aromas of vinegar or nail polish remover (acetone). The taste becomes sharp, sour or harsh, with little to no fruit. The presence of acetic acid in wine is a classic example of spoilage.
3. Yeast, Reduction and Other Aroma Issues
Reduction occurs when wine is exposed to too little oxygen. This can create aromas such as garlic, rubber or rotten eggs. Malolactic fermentation gone wrong may lead to buttery or lactic, yoghurt-like aromas that don’t belong in the wine. Unpleasant yeast smells generally indicate contamination or fermentation under improper conditions.
Why Recognizing Wine Faults Is Essential
Recognizing wine faults goes far beyond avoiding disappointment at the table. It sharpens your tasting skills, saves money and frustration, gives you more confidence when buying or ordering wine, and increases your overall awareness of quality.
Whether you’re taking a wine course, importing wine, or simply want to understand your glass better, learning to identify wine faults makes you a more knowledgeable and skilled taster.
Train Professionally with the Amsterdam Wine Academy
Do you truly want to learn how to identify, taste and understand wine faults? Then the internationally recognized programs of the Amsterdam Wine Academy are the logical next step. Our training combines knowledge, experience and passion — exactly what you need to elevate your wine expertise.
Do you sometimes feel unsure when a wine smells musty, or doubt whether a bottle is still good? Stop guessing. Learn the difference between a stylistic characteristic and an actual wine fault. Explore our courses and discover how to recognize wine faults like a professional. Or contact us directly for personal advice — we’re happy to help!
Frequently Asked Questions About Recognizing Wine Faults
1. Can a screw-cap wine also have cork taint?
Yes, although the risk is lower. TCA (the compound responsible for cork taint) can also enter wine through contamination in the cellar. Several factors can cause unpleasant aromas. A screw cap is neither a sign of quality nor of lower quality — it is simply a different type of closure.
2. What should I do if I suspect a wine fault in a restaurant?
Inform the sommelier or service staff politely. They will usually taste the wine with you and open a new bottle without hesitation. When you order a bottle of wine in a restaurant, it should meet quality expectations — and the owner wants you to return!
3. Are wine faults dangerous to your health?
No, wine faults such as oxidation or brett are not harmful. They only make the wine unpleasant. A musty aroma won’t make you ill. Of course, bacteria or unwanted yeasts can sometimes occur that are harmful, but in practice the greatest health risks lie outside the wine itself — in the glass, or in the rest of the meal.
