Week 5 at UC-Davis
(Above: An old delivery truck parked outside our classroom at Sudwerk)
“Drink all the beer you can and hope the company sells the rest.” - An unamed mentor of Scott Ungermann, Brewmaster at the Anheuser-Busch brewery in Fairfield, CA
I wonder if that used to be their company mission statement? Probably not. This week we had the pleasure of meeting Scott, who received a degree from UC Davis in Fermentation Science back in the day. Marketing tactics and beer styles aside, A-B (Now A-B InBev) has probably done more to further advances in brewing science than any other company in the U.S. and quite possibly the world. They spend a good deal of money on research in their own laboratories and I’m pretty sure that they have donated funds to the school I am attending now. The real benefit to us as students from Scott’s visit in my opinion, was to hear about his journey from college grad to Brewmaster. His first position upon finishing school involved trying to impose changes on how things were being done upon a group of salty old teamsters he was supposed to manage at an A-B facility on the east coast. Sounds like they were throwing the rookie to the wolves to me. Needless to say, resistance was met. He was able to win them over eventually and worked his way up the ladder for the better part of nearly two decades. He seems to love his job, the beer they make and that is something I can respect.
On the curriculum front we have begun to delve into the world of yeast, the little workhorses that beer as we know it would not exist without. We went over the important characteristics of a good brewers yeast such as flavor profile, rate of fermentation and flocculation. This was all familiar to me as a homebrewer. When you are trying to repitch yeast for 8, 12 or even 20 generations like some breweries do, there are other important factors like vitality and viability. Those sound pretty similar right? Vitality refers to how “vigorous” the yeast is, which is its ability to ferment down to the intended final gravity in a reasonable amount of time. A particular batch of yeast that has been used for many generations tends to become exhausted after a while and will simply drop out of the race, so to speak, before reaching the finish line. Tests can be performed on the yeast to measure oxygen uptake, pH change, carbon dioxide production or even glycogen levels to give you an idea of when it’s time to retire the current batch and start anew. Viability is pretty simple. It’s the percentage of yeast cells in a given sample that are alive vs dead. A test using Methylene blue is used to stain the dead cells and leave the live one’s colorless. A viability of 90% and up is typically considered acceptable and anything below 85% is ready to be discarded.
Other areas we touched on were the fermentation vessels that are used today. Some traditional breweries still use open square, Yorkshire stone or Burton Union fermenters, but the most common today is the Cylindro Conical Vessel (CCV). They are usually temperature controlled, have natural circulation from carbon dioxide production, provide an environment for rapid fermentation and use the least amount of space in relation to the volume they hold. This gave the instructors a nice segue to Stokes Law. It’s a formula that allows you to calculate the rate of yeast settling using it’s size, density of both the yeast and beer, viscosity of the beer and gravitational acceleration. When dealing with a 100+ barrel fermenter, it’s probably nice to have an estimated time frame as to when you can move on to filtration.
Next week, we get to go on an educational excursion to one of the most famous craft breweries in the world. I won’t spoil the surprise, but I will say that I can’t wait to have a Celebration after we finish the tour. Hint, hint.