Posts Tagged ‘yeast’

Previous yeast Posts

High Tech Mobile Yeast Sample Centrifuge

Wednesday, May 2nd, 2012

When we pull yeast for cell counting to determine our pitch rate, we have to shake the yeast beforehand to ensure an even mixture before sampling. The problem is that this introduces a lot of bubbles into the yeast sample from the carbonated beer in solution.

Normally we would pull a sample and then let it sit for a while and let the CO2 naturally separate. Not any longer, thanks to our mobile high-tech brewery centrifuge!

portable brewery centrifuge

Captain Chris transporting the mobile brewery centrifuge to the lab

securing the yeast sample to the centrifuge

Securing the yeast sample to the centrifuge

brewery centrifuge at full speed

The brewery centrifuge ramped up to full speed

yeast separation confirmed

Yeast & CO2 separation confirmed!

Clearly we’ve progressed and made great technological strides since our college homebrew days when, thanks to a malfunctioning pump, our brewery was run by bicycle (as evidenced in the below historic photo).

brewery run by bike pumping

We Need Pretzels, Repeat Pretzels

Wednesday, September 21st, 2011

If you happened to be at the brewery the night of August 26th around 7pm, you might have seen something like this:

Afraid that our beer might be ruined, we have kept this story under wraps for the past few weeks. But as of Sunday 9/18 we declassified it. The story is as follows:

As stated above, it all started on the night of August 26th. Commander Matthew was working his side job as an accountant so Captain Chris and Chief Joe were left alone to tend the brewery by themselves. Our third batch of Protector Imperial IPA was at the end of primary fermentation and we started to cold crash it.

Our normal procedure for fermentation is: Primary fermentation, cold crash, pull off yeast, add dry hops, condition and keg.

For some reason, Chris and Joe thought “why not add the dryhops while it’s starting to cold crash?” It wasn’t our normal procedure, but we began adding the hops regardless. To this date we are not sure why.

We moved our ladder to the fermentor and climbed up top to add the hops. As the first pound was added, Commander Matt arrived, eager to help the brewery.

Matt joined Chris climbing half up on the ladder while Joe stood guard on ground in case beer stealing zombies attacked.

Second pound of hops added – no issues.

Chris, on the ladder, began to add the third pound of hops.

Chris: “Whoa! What the?”
Joe and Matt: “What?”
Chris: “Whoa Crap!”
Joe and Matt: “…..”
Chris: “Crap crap crap crap!”

The brewery crew quickly realized that beer began foaming out the top of the fermentor where we added the hops. Chris quickly covered the hole.

Beer instantly started shooting out of the vent tube near Joe’s feet while Chris clamped down the hole up top.

Now normally when something bad happens in the brewery (valve accidentally left open, hose breaks and shoots 180 degree water into the air, etc.) we quickly diagnose the problem and solve it. In this instance, we all stood there for what seemed like 30 seconds watching beer shoot out the vent tube not understanding what was going on. Then,

Joe: “WHAT?!”

Joe quickly covered the hole and the beer stopped foaming out the vent tube. Seconds later,

Chris: “Gah! Don’t cover the hole. Don’t cover the hole!!”

When Joe covered the hole, pressure in the fermentor built up and started spraying beer out the top hole all over Chris’ face and the brewery.

Joe let go.

The three brewers stood there for what seemed like nearly a minute, watching the beer shoot across the brewery not knowing what to do.

Eventually Matt had the good sense to grab one of our grain buckets and put it underneath the vent tube to catch all the beer.

We stood there, beer/foam flowing freely into the bucket until the foaming subsided. Not fully understanding what just happened, covered in yeast and beer, worried that we had just ruined our batch of Protector, we began to clean up the mess.

Luckily the beer turned out fine – though a bit hoppier than batches past. We learned valuable lessons… like never add dryhops to a fermentor without cold crashing the fermentation unless you want a mess of beer over the brewery.

And if you are lucky enough to try this batch of Protector over the next couple weeks, you can really taste the explosion in it.

Matt’s Addicted to Meth

Tuesday, August 9th, 2011

Methylene Blue!

That’s right, Matt is addicted to cell counting. Yeast cells to be exact.

Before we repitch our yeast into the fermentors, we need to get a yeast cell count and determine how viable our yeast is.

Each batch of beer requires a different yeast pitching rate. For example, our Imperial IPA we pitch fewer yeast cells for a slower and warmer fermentation that produces more flavor compounds. Our CA Altbier we pitch more yeast cells for a quicker and colder fermentation to generate fewer flavor compounds to give it a cleaner finish.

In order to know exactly how much yeast slurry to pitch, Commander Matthew Enegren – first string cell counter – mixes 1ml of yeast slurry with 100ml of distilled water. The mixture is stained with Methylene Blue. Dead cells turn blue when stained, but live cells metabolize the Methylene Blue and do not change color. As long as 95% or more of the cells are living, we re-pitch the yeast.

This is one of the most crucial steps of the brewing process. Under-pitching or over-pitching the number of yeast cells for each brew can greatly influence the flavor of each batch.

Matt is most qualified for this job since it involves a lot of counting and Matt is an accountant – he is therefore able to account for living cells much better than Captain Chris or Chief Joe.

matt cell counting with methylene blue