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Brewer’s Little Helper: Initial Thoughts on Yeast

——Update 5/1: I’ve added this fancy-schmancy glossary page in the hopes of making this blog accessible to newer, or even non-, brewers. If there’s anything I’ve missed that demands definition, let me know!——

Two weekends ago I caught my first glimpse of individual yeast cells at Manzanita. While I was thrilled to dive into some lab work, the impetus that compelled us to do so was not exactly joyful. It was getting towards the end of the brew day and we were finishing up a batch of Riverwalk Blonde. Garry harvested yeast from a finished batch intending to re-pitch into the latest brew, but life intervened and he ended up with a sample that resembled yeast soup rather than the viscous slurry he was expecting. Knowing that this didn’t look appropriate, he brought out the microscope to take a cell count. What we found was that we had nowhere near enough yeast. With no other yeast on hand that day’s batch would have to wait. Two or three days later he was finally able to introduce yeast into the wannabe beer, but it was too late. I had a taste of that batch last weekend and the flavor bore a remarkable resemblance to hot dogs. Unpleasant. We had little recourse but to dump that particular batch down the tubes. While it’s never fun to lose a batch, this experience served as my introduction to yeast quality control and as a powerful reminder of what “beer” becomes without the assistance of billions of yeast cells.

A Sample Cell Count

Sample Cell Count: The outlined cells are yeast, the dark blue cells are dead, the amorphous blobs are hops and protein.

Every good brewer, whether at home or in a production brewery, recognizes the importance of yeast. When it comes down to it yeast is what makes beer; brewers merely create the conditions for that process to happen. In fact, the chosen yeast and fermentation conditions have a greater flavor impact than any other single ingredient in the recipe. At a commercial level the key is consistency. Once Garry knew that the wort would have to sit overnight (we didn’t realize it would have to be several nights) we knew it would be problematic. Significant procedural changes made it impossible to produce a Blonde that was true to the brand Manzanita had established. The flavors produced by yeast largely depend on the temperatures employed and fermentation timeline. Wort is a perfect medium for growing yeast or bacteria, depending on what is introduced first, so brewers encourage yeast to gain a foothold as early as possible. When we failed to pitch at the appropriate moment we left a window that unwanted bacteria took advantage of. And that’s the recipe for hot dog beer.

I hope to make the microscope a more frequent part of the Manzanita brew day. It’s a standard industry practice to take a cell count, which notes not only the number of cells but also their health, before every pitch. Breweries harvest yeast from finished beer to re-pitch into their next batch. As they do this the amount of yeast and its viability varies from generation to generation. Knowing our cell concentration would help us come closer to pitching the same amount each time, which would in turn improve our batch consistency. I’m starting to gloss over all of this far too quickly, so I’ll cut myself off here for now. There are volumes that could be written about yeast and I promise to revisit the topic as we ramp up our lab program at Manzanita.

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