Ask a Brewer: Yeast Culture

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Pictured: Safale-05 Dry Yeast, one of the most commonly used strains of yeast
Photo Cred: Ian Steele

Yeah, I know, that title is a real stupid pun. Coming up with article titles is an art, and I’m a first grader with a paintbrush. I can’t be blamed!

Anyway, yeast right? Everybody is aware of it, but even those in the beer industry have limited knowledge on what it is and what it does. As these things go, to the layperson, I’m an expert; to the average brewer, I’ve got a handful of knowledge but am FAR from an expert. Being a true yeast expert means having extensive knowledge of biology, microbiology, chemistry, sanitation/sterilization practices, and probably a whole bunch more science stuff that is well beyond my brain.

So what is yeast actually? It’s alive is what it is. Yeast is a single-celled organism that is responsible for a large amount of processes found in our food and drink today, as well as many other practical applications. Most often, yeast is associated with baking, brewing, and yogurt production/probiotics. In terms of brewing, these little heroes are what make the booze that warms our tummies and soothes our brains, mostly by eating up all the sugars they can find, then crapping out the booze and other byproducts. The most commonly known byproduct of ethanol production via yeast is Carbon Dioxide, which, under the right conditions and with the correct processes employed, can be utilized to carbonate the very same beer that gave birth to the CO2 in the first place. Homebrewers will know this as bottle carbonating or bottle conditioning, in which a small amount of sterile sugar water is added to the beer post fermentation on bottling day. This little extra bit of sugar reactivates any residual yeast still in suspension, causing them to produce a little more CO2 in the bottles, which builds pressure and is forced into the solution. Voila, you have bubbles in your beer.

As always, this post is a surface-scratcher. The varieties of available brewers yeast are many, and no two are directly alike. Mild differences can have huge impacts on resulting flavors. Some yeasts (like Belgian strains) have unique and distinct/easily identifiable flavor profiles and ferment wildly and often produce messes, whereas your average California Ale strain ferments pleasantly and leaves a very clean flavor behind. The possibilities go on forever. The big takeaway, however, is that these little creatures are our good buddies, and we should treat them as such. I personally put my yeast pitches in front of a bluetooth speaker and use the resulting vibrations to keep the buddies happy. Yeast is magic!

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