Can beer evaporate out of an unopened can?

Yes, beer can evaporate out of an unopened can. This process is called "canning off" and it occurs when the pressure inside the can decreases due to temperature changes or a faulty seal. As the pressure decreases, the beer inside the can starts to vaporize and escape through the can's lid.

Canning off can occur if the beer is stored in a hot environment, such as a car trunk on a hot day, or if the can is damaged in any way. It can also occur if the can is old and the seal has started to deteriorate.

The amount of beer that evaporates out of a can depends on several factors, including the temperature, the length of time the can is stored, and the condition of the can. In most cases, only a small amount of beer will evaporate, but in some cases, the entire can can be lost.

Canning off can affect the taste and quality of the beer. The beer may become flat and stale, and it may lose its flavor and aroma. In some cases, the beer may also become contaminated with bacteria, making it unsafe to drink.

To prevent canning off, it is important to store beer in a cool, dark place. The beer should also be stored upright to prevent the lid from coming into contact with the beer. It is also important to check the cans for any damage before storing them. If you notice any damage, such as a dent or a hole, do not store the can.