The Glory of Fungal Digestive Systems: How Yeast Makes Beer Possible

Got Yeast?

We ask that a lot. We put it on t-shirts during the day and see its buds in our dreams at night.

Don’t worry, we’re not latent mold-obsessed sociopaths, or, like… really big lichen fans or anything. We just love science and we love beer. And when you love science and beer, you love those adorable little yeasty buggers. You get to know them, hang out with them, count them meticulously and worry about them in the middle of night.

See, yeast is what makes beer possible. Also, yeast is what makes beer taste like liquid ambrosia poured down by the gods—or viscous cough syrup with subtle notes of gym socks. It all boils down—or up, as you’ll see—to the type of yeast used in brewing. Let’s start with the basics:

Ales are made with saccharomyces cerevisiae yeast that ferments from the top.

Lagers are made with saccharomyces uvarum or saccharomyces pastorianus yeast that ferments from the bottom.

Okay fine, there are a few other strains that brewers mix and match like the engineers in Jurassic Park. But aside from these outlying mutants, most beers are made with those two. Basically, the yeast eats the sugars in the beer-before-it’s-beer and a, um… byproduct of their digestion is alcohol.

Yeah. We said it. You’re drinking yeast farts.

Speaking of things that smell weird, the yeast also produce esters, which is how you get the other notes in beer. Ever hear someone wax poetic about banana top notes and hints of caramel? NO BANANAS OR CARAMEL ARE USED IN BREWING. It’s esters—sneaky little substances that smell totally like whatever your cicerone is sniffing. Helpful in perfumes, pretty freaking awesome in beer.

Now that you’re armed with this fascinating knowledge, you can apply this science to the art of food and beer pairing. Basically, you’re looking to match beer and food that have similar, or complementary, chemical reactions. Some beer flavors bring out hidden tastes in food; others help cut a particularly rich or spicy dish. But it all comes down to those glorious little guys and their astounding digestive system. We’ll drink to that!