Can Beer Go Bad?
The short answer to whether or not beer can go bad is no. Packaged beer does not spoil in the traditional sense of the word like other foods and drinks.
However, beer can go bad in that its flavor can dull or warp over time and cause the beer to become unpleasant to drink.
The Different Shelf Lives of Cask and Tap Beer
Cask and tap beer have very different shelf lives. Tap beer stays fresh much longer than cask beer. Cask beer can be stored for about six weeks if unopened and for only one to two days once beer has been dispensed from the cask. Tap beer keeps for three to six months whether or not it has been tapped during this period.
Cask beer is much more delicate than tap beer. It includes live yeast that continues to alter the flavor and fermentation of the beer even after it is sealed and stored. Cask beer does not include any artificial preservatives and relies only on the metabolic activities of live yeast for fermentation and carbonation. The all-natural ingredients in cask beer make it far less stable than tap beer and make it more susceptible to going flat or spoiling quickly. Cask beer is also exposed to oxygen due to the un-pressurized hand pump mechanism that is used to dispense this beer. This oxidation causes cask beer to spoil very quickly, especially after the cask’s seal is broken.
Tap beer, on the other hand, is not exposed to any oxygen when it is dispensed. Its pressurized tap system keeps its keg fully sealed even after beer has been served from the keg. Also, the filtration of live yeast and the unnatural addition of carbon dioxide and nitrogen to tap beer help preserve this beer and extend its shelf life far beyond that of cask beer.
Drinking Out of Date Beer
When it comes to drinking beer past its expiration date, you don’t have to fear for your health. Once beer is done brewing and has fully fermented, no harmful pathogens grow in the beer. Unlike other expired foods—like dairy and meat—that can lead to severe health problems if consumed, beer won’t make you sick if you drink a bottle that’s out of date.
However, that doesn’t mean you should ignore the expiration date on your beer. While it might not physically harm you, drinking expired beer can certainly be unpleasant for your taste buds. When beer expires, it oxidizes due to exposure to oxygen during packaging and the release of oxygen from oxidized compounds in the beer itself. This oxidation alters the flavor and aroma of the beer over time. At best, expired beer has a dull aroma and muted flavors. At worst, out-of-date beer develops unpleasant flavors that cause it to taste soapy and excessively bitter or acidic. The unsavory taste of expired beer can even turn you off of your favorite beer for good.
How to Tell if Beer Has Spoiled
If you want to avoid drinking beer that is past its prime, you don’t necessarily have to go by the official expiration date printed on its bottle. Many beers taste perfectly fine after their expiration date has passed. Some beer drinkers even prefer the taste of certain types of beer after it is technically out of date.
Most beer continues to taste perfectly fine six to nine months past its expiration date. Since there is no danger of getting sick from drinking beer even if it has gone bad, you can rely on signs other than expiration dates to determine whether or not its time to throw out your beer.
Popcorn or Paper
When tasting beer that is past its expiration date, watch out for any hints of flavor that taste similar to popcorn or paper.
Diacetyl is a compound that is present in almost every beer. This compound has a strong buttery flavor that can cause beer to taste distinctly like popcorn after it has gone bad. Oxidation can cause beer to develop a papery, cardboard-like flavor that tastes stale and is also a sign that beer has spoiled.
Beer goes bad more quickly when it is bottled in a colored bottle. Colored beer bottles are not able to protect the beer inside from UV rays.
Over time, exposure to unblocked UV rays can lead beer in colored bottles to develop an unpleasant skunky flavor and aroma.
Low Alcohol Content
A low alcohol content can cause beer to lose its flavor more quickly than beer with a higher alcohol content.
Beer with an alcohol content of 6% or below does not age well and its flavor tends to dull and warp rather than develop as it ages.