Man Beer School: Yeast Is Like A Lead Singer

Man Beer School: Yeast Is Like A Lead Singer

Yeast. It’s kind of a nasty word. Scientifically, it’s a fungus. To us humans (scientifically, we’re homosapiens), the 1,500 known yeast species serve a wide variety of purposes. But this isn’t a science blog, it’s a fucking beer blog, so we’re going to skip 99% of all known yeasts and cut right to the good shit: Saccharomyces cerevisiae and Saccharomyces uvarum. Within each species of yeast, there can be thousands of different strains. To brewers, anything outside of the two aforementioned species will be labeled “wild yeast” (sometimes with the exception of Brettanomyces which will be covered later).

These little bastards are the lead singers in the rock and roll band we call beer.(For those of you who have just stumbled upon this blog, we have already covered that malt is the rhythm section and hops are the lead guitarists).

So, what makes yeast the front man? First of all, yeast hardly ever wears shirts. Secondly, yeast is what makes our bubbly beverage sing. The thing that separates beer from non-alcoholic oatmeal is yeast fermentation. The byproducts of fermentation, other than the obvious alcohol and carbon dioxide, are what give our beer character and a unique voice. A well-tuned singer with a wide tonal range, perfect pitch and over -the -top confidence is an ideal and versatile front man in any band. Think of desirable byproducts of fermentation like these traits. Undesirable byproducts of fermentation (called “off-flavors”) think of those as piss, blood, sweat and vomit.
Those of you who really know your beer might say “H., lager beers are fermented so that yeast flavors are muted.” Well, yes, you’re right. But shut up, I’m in the middle of a compelling analogy.What is Yeast?Yeast are unicellular and asexual fungi (sound like any lead singers you know?). Originally thought of as magic, the proof that yeast is a living organism was provided in 1857 by our dear friend Louis Pasteur. For the first few thousands years of brewing history, beers were either fermented by accident, by wild yeasts (which are prone to produce crazy sour flavors) or by cultivating the krausen (actively fermenting yeast from a batch of beer) and repitching into a new batch.Yeast is what turns boiled barley and hop water into beer. In a short explanation, yeast wants to eat sugar (in this case, provided by the malted barley). In doing so, it creates byproducts that include (but are not limited to): ethyl alcohol, carbon dioxide, esters, fusel alcohols, ketones, phenolic compounds etc. In fact, there are over 600 flavor and aroma compounds that yeast can contribute to a finished glass of beer.

When you pitch brewers yeast into a batch of wort (unfermented beer), the healthy yeast will start reproducing like crazy and eating all the sugar it can find (and I repeat my question, does this sound like any lead singers you know?). I should note that, due to the science of latex–and the science of pulling out–many lead singers do their best not to reproduce, despite a tendency to kind of spread their seeds everywhere. Fortunately for us, modern science has not created a condom small enough for yeast penis, which would be a waste of time anyway because yeast reproduce asexually. Thank Christ lead singers (or any of us) can’t do that!

Types of Yeast

Most brewers are focused only on two types of yeast: “top fermenting” (S. cerevisiae — ale yeast) and “bottom fermenting” (S. uvarum — lager yeast). Then there are other types of “wild yeasts.” Brettanomyces (or “Brett”) is sort of a gray area because for most of brewing history, it was considered a wild yeast, but now many brewers are producing beers with intentional Brett additions and some with exclusively Brett fermentations.

Yeast, Our Front Man

Yeast fermentation creates ethyl alcohol and carbon dioxide, but where our little friends really shine is in their other byproducts. In a well-fermented beer (particularly ales), you may find fruity, flavorful esters or clove-like or smokey phenols. In a shitty-fermented beer, you can find nasty off-flavors like rotten eggs, goats, plastic or Band-Aids. Gross. Have you ever had a nice hefeweizen that tastes like bananas? Yep, that’s yeast doing it’s thing. A nice, full-flavored pale ale with hints of fruitiness? Yeast again. Yes, its flavors and off-flavors are up in front stage, singing, crooning, screaming or, in the case of lagers, whispering quietly.

A good front man is one that matches his band. Put the best black metal scream-singer into a reggae band and you’ve probably got some shitty music (confusing at the very least). The same is true for yeast. Put a farmhouse yeast into a Kölsch and you’re going to upset some drinkers and confuse them all.

Just as a band is really only as good as its front man, a beer is only as good as its fermentation. It’s not going to be the other ingredients in a balanced beer recipe that make it truly bad, it will be the yeast. And, to clarify, it’s not really the type of yeast, but the conditions under which it ferments that will make or break the beer. Yes, there are strains of yeast that are more well-suited to a certain style, but shitty fermentation makes for shitty beer. The end.

As always, feel free to reach out if you have any questions at write.h.vulgare@gmail. Until next time….

-H. Vulgare

Man Beer School is a regular column exploring everything you ever wanted to know about beer.