Everyone has a different idea of what the perfect beer tastes like, but there's one thing most people can agree upon: it shouldn't taste like gym socks.
You're much less likely to receive a bad beer than a botched cocktail or corked wine, but it happens more than you might think. To help better understand the brewology behind why a beer doesn't taste quite right, we chatted with Matt Eggers, a certified cicerone who runs the taproom at Woodland Empire Ale Craft in Boise, Idaho. Here are nine of the most common off-flavors.
"'Did he really just say baby vomit?' Yeah, I did."
This term has become a catch-all adjective for bad beer, but it actually describes a specific taste. When beer is exposed to light, UV rays create a photochemical reaction with the hops that causes a smell that's equal parts wet animal and flatulence. Brown glass bottles help stop this reaction, but green and clear bottles are notoriously susceptible. Companies that stick to clear/green glass are rumored to actually account for skunking in their flavor profile. "A good way to understand this flavor is to pour a good craft pilsner into two glasses and leave one in direct sunlight for a few minutes," says Matt. "The difference is noticeable that quickly."
If it tastes like cheap vodka, it's referred to as "hot beer". This defect is most prevalent in beers with high ABVs that were not aged long enough.
Creamed corn or cooked vegetables Dimethyl sulfide (or DMS) is a result of infection or lazy brewing practices and stinks like boiled cabbage. Watch for it in pale lagers.
If your beer tastes like something out of a movie theater (and not one of these awesome, boozy movie theaters), then the culprit is likely diacetyl, which is caused by either a bacterial infection or removing the beer from the yeast too quickly. The most common offenders for this are lagers.
Cardboard If a beer isn't properly packaged or is moved through multiple temperature fluctuations, it can throw off the oxygen levels. Bottles, cans, and kegs are all susceptible to this, and it results in a flavor that's "similar to licking a cardboard box".
If your beer tastes like a Granny Smith it's probably due to acetaldehyde, a chemical that occurs naturally in the brewing process but is generally consumed by the yeast. This is a sign that the beer might've been rushed and bottled before the fermentation process was complete. Matt says this can also result in a cut grass or latex paint flavor. Bonus facts about acetaldehyde: some blame it for hangovers, and it can cause certain people to turn red in the face.
Baby vomit "'Did he just say baby vomit, really?' Yeah, I did," says Matt. It's a result of butyric acid created due to poor sanitation at either the bar or the brewery.
Gym socks or stale cheese
The hops have either gone bad or there's just too much of them. The sweaty/stinky flavor is produced by isovaleric acid, the slightly older and less vommity cousin of butyric acid.
Vinegar "If you've ever opened a beer and thought it would be better used as a salad dressing, you know the problem is infected beer," says Matt. Sour and wild beers aside, vinegar aromas are present because wild bacteria has turned sugars into acids instead of alcohol.