Human beings have been brewing beer for millennia, but only in the past century and a half have we developed a reasonably informed understanding of yeast’s critical role in beer making. Today’s brewers often say that brewers make wort and yeast makes beer, a clear indication of the respect with which modern brewing treats our favorite microbes.
And yet, there can be too much of a good thing. A yeasty flavor or aroma is appropriate, even critical, to a handful of styles, but if your latest homebrew reminds you of a Vegemite sandwich, or even of eggs, then it’s time to take a closer look at this off-flavor of the week: yeasty! Here are some possible culprits.
You’ve poured too much sediment.
This culprit might seem obvious, but I can’t tell you how many times I’ve watched a homebrew rookie swirl the bottle dregs so that everything makes it into the glass. This is almost always bad practice! By all means, rouse the sediment in your Weißbier, but decant a pale ale with care.
Your beer is too young.
Yeast cells flocculate out of solution to varying degrees after fermentation, and some strains do so more readily than others. If you find that a particular strain remains suspended longer than you’d like, consider switching strains. Or cold crash the beer, which is to say, drop the temperature to just above freezing for a few days before you rack it.
Your beer is still too young.
But don’t cold crash unless you’ve tasted your homebrew first! It’s not just a matter of flocculation, after all. Yeast reabsorbs fermentation by-products even after active fermentation is well in the past. Even if it looks like nothing is happening, billions of yeast cells are still working away to condition your beer. Leave your beer on the yeast a little longer than you think you should, and you’ll probably be glad you did.
Your beer is too old.
Conversely, it’s possible to develop yeasty flavors by leaving fermented beer in contact with an old yeast cake for an extended period of time. Practically speaking, some of the lazier homebrewers out there (I speak here of myself) routinely leave homebrew in the primary fermentor for several weeks, even a couple of months, with no issue. If, however, you detect a yeasty bite in a batch that you forgot about for, say, the better part of a year, then you might suspect yeast autolysis, a condition in which yeast cells literally self-digest in the absence of other nutrients.
Check out some of the other articles in our off-flavor series.