You may have experienced beer in the past with that unpleasant smell and aftertaste reminiscent of that artificial butter on movie theater popcorn. And to make matters worse your beer feels flat and lays like an oil slick on your palate.
And contrary to what Harry Potter fans might think, most of us would agree that butter and beer shouldn’t mix, it’s a ‘’beer buzzkill’ of major proportions.
So What’s Going On Here?
Diacetyl (pronounced “die-ASS-it-uhl”) is the culprit and it’s an organic compound present in all beer. It is easier to detect diacetyl in lagers or lighter beers compared to stronger or more complex beers.
Diacetyl is a normal byproduct of all beer fermentations, yeast both produce and reduce it. Brewers commonly raise in fermentation temperature slightly at the end of fermentation to encourage an accelerated reduction of diacetyl.
Sluggish and unhealthy yeast can also produce high levels of diacetyl, but sometimes lactic bacteria is a factor (think dirty draft lines).
The Problem is Incomplete Fermentation
“There’s a saying in brewing circles that brewers don’t make beer,” as Medium astutely explains “they make wort (unfermented beer) that is food for yeast. It’s the yeast that makes the beer.”
And buttery beer is a sign of poor yeast management.
Maybe the brewer has taken the beer off the yeast too soon. Or it could be that the brewer allowed fermentation to happen at the wrong temperature — possibly the mix was too cool.
“If you’re getting that diacetyl character out of a beer that you’re drinking out of a bottle or can, I’d certainly reach out to the brewery, because the brewery will want to know that from a quality-assurance perspective,” says Dennis Mitchell grand master judge and member of the American Homebrewers Association governing committee told the Takeout. “If you’re at a beer bar, you might even ask when the [draft] lines were last cleaned. If they can’t tell you, that might be indicative of a problem.”
Diacetyl in beer unavoidable, and it’s in all the beer we drink to some degree. It’s a question of moderation, but when things go array, it can lead to a major beer buzzkill…
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