How to tell if your wine has gone bad
At least until it has been opened - then, like with most foods, it's a different story.
An open bottle of white wine will stay fresh for just one to three days. Opened red wine, on the other hand, will be ok for one to two weeks.
However, if you're skeptical of expiration dates, or you don't remember when exactly you opened that last bottle of Merlot, use these tricks to guide you.
It'll begin to brown
Wine is a lot like fruit: it browns when exposed to oxygen, according to Wine Folly. Some red wines are naturally browner than others, so the key is to try and remember the wine's original color.
It looks cloudy
If you notice that your wine is looking cloudy, it may be time to toss it. Cloudiness, which is also caused by extended exposure to oxygen, may mean that your vino is growing yeast or bacteria.
It tastes fizzy... and it's not sparkling wine
A carbonated taste indicates that there's been an unintentional second fermentation in the bottle, according to wine merchants BBR. This could be due to poor wine making, but more commonly because it has been open for too long.
It smells weird
With bad smell comes bad taste. Like most foods or drinks that have gone bad, a funky smell will probably stop you from eating/drinking these items. Wines that have been open for too long will have a sharp, sour smell, similar to nail polish remover or vinegar. According to Wine Folly, "these aromas are from chemical reactions from the wine being exposed to heat and oxygen, which causes bacteria to grow that produce acetic acid and acetaldehyde."
So when in doubt, throw it out.