1.corked2.cooked3.oxidized4.sediment5.sulphur6.refermentationEven with modern winemaking, wine storage, wine cellars and shipping technology, about five percent of all wines arrive at the table bad to some degree. Here are some tips on how to spot and avoid bad wine.CORKINGIt all begins with a cork. Even in this day of high-technology plastics, many bottles still have a cork stopper. Cork, a product of the bark of selected Mediterranean trees, has many highly desirable and hard to duplicate attributes. It is lightweight, resistant to disease and airflow, flexible and attractive.But as a natural product, cork is subject to attack by microorganisms. Certain species of fungus, present anywhere wine is stored, can infiltrate the cork producing a compound called TCA ( or 1,2,4-trichloroanisole).TCA and other factors produce unpleasant odors and tastes in wine, similar to wet cardboard, mushrooms, mold and even unwashed socks. Even if the odor is mild, the taste may be somewhat bitter and lack fruitiness.COOKINGMoving wine from the vineyard to the home or restaurant table involves trips of dozens to thousands of miles. High temperatures cause liquids like wine to expand slightly, which increases the pressure inside a corked bottle. This pressure can cause the cork push up slightly. When the wine cools down again, it can oxidizeIf the temperature becomes high enough, the wine can literally cook. If cooking occurs, the taste of the wine will be altered and the fruit flavor will convey more stewed prune than fresh berry. Look for corks that sit above the lip of the bottle, or levels of liquid too far near the base of the neck.OXIDATIONImproper wine storage, such as excessive heat or cold and incorrect humidity levels, can cause corks to shrink or crack. Either of these will cause infiltration of unwanted amounts of air into the bottle, causing oxidation. Oxidation means oxygen combines with the wine and can cause chemical changes. Oxidized wine can taste stale and change to a brownish color. Some amount of air, in small amounts over a period of years, may be desirable to ensure proper aging. But even well before producing vinegar, it’s possible to spoil a wine from allowing too much air to reach the wine. Wine which has become fruitless and resembles old Madeira (deliberately produced in open air vats) is almost certainly oxidized. SULPHUR and SEDIMENTSSulphur is a common preservative in winemaking to help stabilize wine. In excessive concentrations, it produces an undesirable aroma and flavor that resembles moth balls or burnt matches. Some sediment in wine is acceptable, normal and fairly common with some varietals. Ports and older wines, even whites, often accumulate material and should be poured properly or decanted. Tartrate crystals or “wine diamonds” will naturally form in some wines if the temperature drops too low. Avoid pouring and tasting them, though they are harmless and a result of the fermentation process.REFERMENTATIONIn rare cases, it’s possible for dormant yeasts to remain in the wine and some amount of additional fermentation to take place during years of shipping and storage. Champagne, for example, is deliberately refermented in the bottle. But for non-sparkling wines, this effervescence is undesirable but easily spotted.Techniques of manufacture, bottling, shipping, and storage continue to improve to reduce the chances of encountering one of these conditions.
