Have you ever had that experience in a restaurant or even at home? When should you send the bottle back in a restaurant or ask the wine retailer to replace the bottle? Fortunately, "bad wine" (as opposed to wine that is not very good) does not happen frequently with today's modern wine technology. However it still occurs and you will taste it on occasion.There is a difference between just not liking a particular wine and getting one that is "spoiled"; you should know the difference. Any purchased wine may have more tannins than you like or be more acidic (sour) than you prefer. It could be less sweet or fruity than you are used to but these are not reasons to send the wine back. Wine that is unbalanced to your taste in tannins, acid or sugar will not have off-smells; you will just notice a taste you do not care for. To send the wine back or even to ask the wine server to check the wine by smell and taste, you want to have some idea of what the most common "off tastes" in spoiled wine are and almost always these can be detected by aroma and then confirmed by taste. If you swirl the wine around in the glass, the alcohol will carry chemicals to your nose, some of which may result in offensive odors. The most common types of spoiled wines are: oxidation and heat damage, contamination with unusual bacteria or yeast which produce objectionable odors, and chemical byproducts of uncommon chemical reactions within the wine itself. Any of these spoilage types may be just barely detectable or may be overwhelmingly bad. If it is just barely detectable you may benefit from consuming the wine as usual and using it as a teaching example at your table.Oxidation/heat The most frequent spoiled wine you will run into is wine that has suffered too much exposure to oxygen. It is said to be oxidized. While some wines are intentionally oxidized such as sherry or tawny port, most are not. When they take on a sherry-like nutty odor or caramel taste, and the color of the rim of the wine in a glass held against a white background looks to have yellowish or brownish tones, that wine is in the process of spoiling. Just leave a bottle of opened wine on your kitchen counter with a cork in it and sample it daily for a week. You will learn how oxidation changes the taste of wine. You really should try this experiment if you haven't already, so you confidently do not have to tolerate an oxidized wine at high restaurant prices.Madeirization (like Madeira wine) is the application of both heat and air (oxygen) to wine so that it tastes like almonds and candied fruits; perhaps desirable in dessert wines but not acceptable in dry wines. It is a subtle distinction from just oxidative changes and for practical purposes, I just lump this spoilage under the term "oxidized." It will still have a sherry-like smell and a baked fruit taste. Clues to expecting an oxidized wine before smelling or tasting the wine would be:Leakage of wine crud under the cap at the mouth of the bottleA cork that is raised above lip of the bottle before openingA very crumbly, dried out cork upon removingAn amber or brown rim of white wine in the tilted glass held against a white backgroundAn onion-skin rim of rosé wine in the tilted glass held against a white backgroundA tawny or brown rim of red wine in the tilted glass held against a white backgroundOxidative and/or heat damage accounts for 85-95% of the spoiled bottles you will ever come across. It is often due to storage of wine in too warm a temperature.Microorganism ContaminationThe next major cause of spoiled wine is undesirable yeast or bacterial contamination of wine that produces objectionable odors and tastes. A vinegary taste or smell can be due to acetobacter bacteria; a wine aroma that is like a mouse cage, old Band-Aids, dirty socks, sweaty horse or manure smell is most likely due to Brettanomyces/Dekkara yeast contamination. "Brett" contamination is found more frequently in European red wines that are not as acidic. I have encountered it more frequently in Italian wines but it can occur anywhere. It may range from just a small amount which seems to give a desirable "earthy" smell to the wine, to larger amounts which are objectionable and have the above smells. It is thought to originate in the open grain crevices of wooden barrels that are reused each year and from other winery equipment. Wine microbiologists will tell you that every wine has a little Brettanomyces/Dekkara in it but whether it is a problem depends upon which strain, how much and how active the yeast is. A geranium smell is spoilage by lactic acid bacteria in a wine containing sorbic acid. It is now a rare spoilage source. Microorganism contamination of wine may account for 5% of the spoiled wines you ever come across.Chemical ReactionsChemical byproducts of uncommon chemical reactions within the wine itself is the third major category of spoiled wine. Too much hydrogen sulfide produced from the sulfur dioxide used before bottling to prevent bacterial and yeast growth can sometimes produce a sulfur or burnt match smell and a pronounced garlicky or onion taste due to mercaptan chemicals. A "corked" wine is one that has too much of a chemical called 2,4,6-trichloroanisole or TCA. It produces a moldy newspaper, wet dog, damp cloth, or damp basement odor and may run as high as 2-3% of all wine that has natural corks. It used to account for perhaps 10-15% of all spoiled wines but in the recent decade with new synthetic corks and metal twist-off caps this problem has decreased significantly. The exception would be if you are fortunate enough to be drinking older vintage wines. Then you will run across the problem more often but still infrequently, perhaps 2-3% of spoiled wine. Hmm - vintage wines! Maybe that's a problem I want to have.There can be many other reactions that result in spoiled wine. If you question whether a bottle is on its way to spoiling or not, ask the wine server to check it out or give it to someone else to confirm or deny spoilage. If they agree, have them replace it with a different brand of a comparably priced wine rather than another bottle of the same wine. The same brand of wine has a higher probability of having the same spoilage. If the management does not agree that the wine is spoiled but you still don't like it, move it to the side and drink another beverage with your meal.
