Cork pushing out of top, Is it safe to drink?
Safe? Yes. Desirable? Probably not.
If a bottle has been exposed to excessive heat, the wine inside could start to expand, which can push the cork up, and there might also be sticky signs on the neck that wine has leaked out. This doesn’t always mean that the wine is ruined. But if the temperature has affected the wine enough, it could be “cooked,” which means the flavors will taste cooked, as if they were stewed, baked or canned. Not only will the wine’s freshness be compromised, but its color might start to look a little browner. This is also know as Maderisation . So remember to store your wine in cool locations that are out of direct sunlight
Look at your wine.
Step 1: observe your wine. You can tell a lot through the way the wine looks. But the very first sign that the wine is probably bad does not involve the beverage itself, but the cork. If you notice that the cork is slightly pushed out from the bottle, this means that the wine has overheated.
Now focus on the color. You can easily tell when a wine has lost its shine, its crispness, its color. If your wine looks like it faded and is discolored, then you are most likely about to drink an oxidized wine. Whites and reds both take on a brownish hue – a deeper yellow or yellowish brown for whites – when exposed to air. However, keep in mind that an aged wine will naturally have a slight brownish tint to it; young wines, on the other hand, fade in color only when in contact with air.
Smell your wine.
Sometimes, your wine does not have that toasted bread or fruity aroma that is so pleasant to the nose; instead, it will have a repulsing wet cardboard, moldy basement or even wet dog smell. In that case, your wine is probably corked. TCA, the chemical responsible for that phenomenon, gives the wine those negative flavors that we’d all rather avoid. It won’t hurt you to drink a corked wine, but we cannot promise an immense gustatory pleasure…
There are a few other aromas that you may have to watch out for: ever came across a wine with a strong nail polish remover, rotten eggs or vinegar smell? There might be a little sulfur problem here, and again, although it shouldn’t be harmful to drink it, we wouldn’t advise you to – the experience is not the greatest.
Taste the difference.
Sweetness: It can be a little trickier to taste if a wine has gone bad, but a good giveaway for red wine is often a sweet, port-like taste (unless you're actually drinking Port). This happens when the wine has been exposed to too much heat.
Bonus info: Storage matters – keep your wine stored in cooler areas of your home and not in the windowsill (even if it complements your French drapes).
Bubbles: There are wines where you expect a fizzy sensation, and there are those you don't. To create the bubbles you find in Champagne, the wine undergoes a second fermentation, where the yeast magically transforms itself to bubbles. However, in wines that aren't supposed to be bubbly, sometimes the yeast rebels and starts its own second fermentation, making wines that aren't supposed to be fizzy… fizzy.
There you have it. Well, sort of. Learning to spot these flaws can take years of practice, but now you have a good starting point.