All beer, whether in a can, bottle, or keg, will go bad eventually due to biochemical breakdown caused by oxygen, light, bacteria.
Though all beer eventually spoils, some evolution over time is desirable! Like wine, many styles of beer go through an aging and conditioning process that develops flavor and complexity.
In general, the higher the ABV, the better a beer will develop over time. This is because the additional alcohol prevents the development of bacteria or other undesirables.
Beer should absolutely be stored unopened, but even unopened beer will get stale or skunky eventually. Once you open a beer, you expose it to oxygen, meaning you should drink it within a couple of hours for the best experience.
– Expiration Date – Leakage – The hiss – Head – Aroma – Color – Taste
Beer that is many years old, however, has had its entire molecular structure changed over time, and should be avoided. Drinking beer this old can result in unpleasant issues like vomiting, nausea, and stomach problems.
Due to the way it’s produced, bottled beer naturally has more oxygen in it than canned beer. Brown bottles also let a little bit of light in. Green or clear bottles let in even more. Since air leads to degradation, cans are the best bet for long-term beer storage.
– Refrigerate, but don’t freeze. – Keep the beer out of the light. – Store your beer upright.