Brooks on Beer: The 10 Most Common Beer Defects

Written by Jay R. Brooks for

When beer goes bad. Image courtesy
This time of year, I spend a week in Denver, attending the country’s biggest beer festival: the Great American Beer Festival, or GABF. For a number of years, I’ve also been privileged to be one of the judges who help determine which beers will win gold, silver and bronze medals in 84 categories. This year was a record year, with more than 4,420 beers from 673 breweries in 48 of the 50 states, plus Washington, D.C., and Guam.

For three days, 184 of my fellow judges and I hunker down in the basement of the hotel where the judging takes place. Our ultimate goal is to find the best of American brewing. One of the ways we accomplish this is to eliminate beers that we think are not as good as others, that have flaws we don’t find in others.

These may not even be the 10 most common defects because, as far as I know, no one has ever ranked beer defects by how often they occur. The 10 I chose are the flaws you’re likely to encounter if you drink your fair share of beer. For each one, I’ve given its common descriptor, the scientific name brewers use and its likely cause or causes.

It’s possible that you have tasted one of these defects in a beer you’ve enjoyed and didn’t realize it wasn’t supposed to be there. For some defects, it’s considered a flaw only if it’s too pronounced. At low levels, it may be perfectly acceptable — even desirable. Or it may be that you noticed one of these off-flavors but didn’t know its cause. Some causes are quite complicated, so I’ve tried to simplify them as best I could. Hopefully, this will give you a better sense of some of the more unusual flavors you sometimes find in a beer but wished you didn’t.

The defects

  • Band-Aid (chlorophenol): You just know something is out of whack when your beer smells of adhesive bandages. This aroma also may remind you of disinfectant or diaper aromas. It’s the artificial quality that really stands out in this defect, which usually is caused by a problem with sanitizers or yeast.
  • Butter or butterscotch (diacetyl): Think of that artificial butter aroma and flavor from movie-theater popcorn, and you’ve got the diacetyl character in some beers. At low levels, this can be an enjoyable flavor component. But just like popcorn that’s swimming in butter, too much can make for an unpleasant experience. Beers with too much diacetyl often are called “butter bombs,” and the cause is often a problem with the yeast and amino acids. Continue reading “Brooks on Beer: The 10 Most Common Beer Defects”