5 Common Wine Flaws (and How to Detect Them)

Unfortunately for makers and drinkers alike, sometimes things go awry in the winemaking or wine storing process. Chemical, environmental, and bacterial mishaps can all result in a spoiled bottle of wine. Fortunately, there are ways to detect and even correct a bad batch before you drink it.

Here are the five most common wine flaws, how to find them and, if possible, how to fix them.

1. Oxidation

Oxidation is the most common wine fault as it can occur anytime during the winemaking practice, including after the bottled is sealed. When oxidation occurs, the presence of too much oxygen in the wine causes its chemical balance to collapse. The effect is often described as flattening, because oxidation dulls both the flavor and color of red and white wines. If your wine tastes flat or bitter, it is likely oxidized.

Unfortunately, there is no way to salvage an oxidized bottle of wine. You can, however, make an opened bottle last longer by using a preservation system like a vacuum pump stopper.

2. Cork Taint

Chemical compound 2,4,6-Trichloroanisole (TCA) is responsible for another common wine fault known as cork taint. The contaminant can enter wine through oak barrels or the corks themselves. If TCA is present where large volumes of bottles are corked, the toxin can ruin entire batches of wine.

You can recognize cork taint by its distinct odor: a bouquet of mold, wet paper, and dirty dog. Wines polluted by TCA typically cannot be saved; however, some experts suggest you can remove toxins using plastic wrap. Allegedly the compounds in plastic wrap can chemically draw TCA out of wine, but you may be better off just opening another bottle.

3. Sulfur

Sulfur is added throughout the winemaking process to prevent oxidation and bacteria growth. If handled correctly, sulfur can easily go unnoticed in wine. If not, however, it can result in some pretty unpleasant tasting and smelling flaws.

There are four main sulfur compounds that can wreck a good bottle of wine when excessively present:

• Sulfur dioxide, which is added to wine as an antioxidant and preservative
• Hydrogen sulfide, a natural byproduct of fermentation
• Mercaptans, a reaction between hydrogen sulfide and other ingredients
• Dimethyl sulfide, a breakdown of amino acids

Telltale smells from sulfur compounds include the aromas of rotten eggs, burnt rubber, or asparagus. Sometimes the sulfur is so overwhelming that the wine cannot be saved. You can improve the flavor, however, by using a decanter to aerate the wine for five minutes to two hours.

4. Heat Damage & Lightstrike

Wine that is exposed to either high temperatures or too much sunlight can result in these two flaws. Heat damage can essentially cook wine, leaving a sweet but processed smell behind. In fact, wine ruined from heat damage is known as “cooked” wine in the industry.

Lightstrike occurs when a bottle of wine has had excessive exposure to ultraviolet (UV) radiation. White wines are particularly susceptible because they don’t have the same protective phenolic compounds as reds. Lightstruck wines are recognizable by their damp cardboard or wool taste. Unfortunately, heat and UV damage cannot be rectified. You can prevent them, however, by storing wine away from direct sunlight ideally at a temperature of 55°F.

5. Microbial Contaminants

Microbiological flaws can occur for a number of reasons because wine itself is a result of microbial exchanges. Lactic acid bacteria, for example, play a role during fermentation to turn malic acid into lactic. Once this process is completed, there can be unintended leftover bacteria that react with other compounds and create unpleasant results like re-fermentation or swampy wine.

Other microbial flaws include volatile compounds produced by yeast and unchecked bacteria growth that escaped sanitization. Different reactions from microbes produce different flavors and smells, so there is no single way to recognize them. However, you will almost certainly notice that the bottle is spoiled. There is no way to fix a microbiological problem. The flavors and smells emitted from this kind of contamination are created either by living organisms themselves or their feces. You’re better off with a different bottle.

Preventing Flaws

These are just some of the most frequently encountered wine faults for both makers and drinkers. Some flaws, like sulfur compounds, can be remedied while others, like heat damage, cannot.

The easiest and best way to prevent wine flaws is to practice proper storage of your wine. The best controlled conditions are at 55°F, 70% humidity, and away from harsh lighting and sunlight.

By far, a wine fridge is the most convenient way to safely store your wine. Not only can you set the temperature for what you want, but you can also keep your wine out of harms way and in a safe place until you’re ready to drink it.

Regardless of storage conditions, it is important to know the signs of faults in wine so you can recognize them before you drink or buy a spoiled batch. Also, so that next time a waiter pours a taste of the wine before they leave the bottle, you’ll know exactly what you’re looking (or smelling) for.

Wine Storage Tips:

• The 5 Dos & Don’ts of Wine Storage
• How to Choose the Perfect Wine Cooler
• Why Wine Serving Temperatures Matter
• Wine Storage Temperature: How to Keep Your Wine at Its Best