Wine is a fickle beverage that can spoil easily, so storing it properly is important. Understanding how wine should be stored is also important when you are making a decision to purchase from a new store. If you are in a store that seems overly warm, or that has bottles that seem to have been sitting upright for a long time, understanding how a wine should be stored will help you make the decision of whether or not to make a purchase at that wine store.

The two main factors that can affect a wine and spoil it are temperature and storing position.

Wine Storage Rule #1: Store it in a cool, dry place at a temperature of 70 degrees or less.

Since wine is simply fermented grape juice, the juice can spoil easily if it is not stored at the proper temperature. Once the temperature reaches above 80, your wine can begin to “cook,” and if the wine sits there for too long, or crosses over 90 degrees, it will be ruined. An easy way to tell if a wine has been “boiled” by heat exposure is to smell it. If the wine smells of stewed fruit and raisins, it has probably turned due to heat.

As an example, think about a plastic bottle of apple juice. If you let that apple juice sit in your hot garage for more than a few days, the bottle will start to expand and, as the juice cooks, it will start taking on rancid qualities. Even though wine is stored in a glass bottle, which means you won’t see the bottle expanding from heat, the same thing that’s happening to the apple juice is happening to the wine. This is why temperature is so important.

Avoid keeping bottles near heat sources such as a radiator, and never store them in places that don’t have access to a cooling source, such as a garage or unventilated basement. If you want to be on the safe side, just place your bottles in your fridge.

Wine Storage Rule #2: You should always store wine on its side, rather than upright.

You may think that because you’ve seen wine sold upright in stores, this is the correct way to store it, but unfortunately, it is not. That’s because while the cork does a lot to protect a wine from its frenemy oxygen, if the wine is upright, the liquid can’t stay in constant contact with the cork, which allows the seal on the bottle to loosen, and more oxygen to seep in and spoil the wine. Keeping the wine in constant contact with the cork maintains the seal and protects the wine. At home, you can ensure this through a tabletop wine rack or even a custom built wine cellar.

This is why if you enter a store that is not only warm, but also seems to have had the bottles they are selling sitting upright for a prolonged period of time, you could be stepping into a terrible combination. Instead of paying for a nice bottle of wine, you may be buying vinegar instead. If you notice this, simply back out of the shop slowly, and find a different place to purchase.