The information technology professionals who keep our computers, network connections, and mobile phones up and running don’t receive nearly enough credit for the vast majority of the time when things work as intended. Instead, they hear from us only when there’s a problem. The situation isn’t all that different for brewers. We might never stop to think, “Wow, they really dialed in the temperature on that English yeast,” or “It must have taken a great deal of trial and error to achieve this harmonious balance of oak and esters.” But when things go wrong, we notice.
Fortunately, there’s a whole vocabulary to describe what we perceive. What follows is a quick reference to some of the most common off-flavors found in beer, as indicated on the Beer Judge Certification Program (BJCP) score sheets used in competitions. Whether you read about one of these off-flavors in our Beer Reviews, discover one of these off-flavors in the beer you’re drinking, or you receive feedback from a judge on your homebrew, you can use these descriptions to understand what might have gone wrong in the beer. For homebrewers, you’ll discover tips to help keep those flaws out of your next batch.
Acetaldehyde
How the BJCP describes it: Green apple–like aroma and flavor.