Back to Basics: Yeast 101

As I sit here in a Miami hotel room (our temporary pit stop before heading all the way down south to the Keys for the Key West BrewFest), I can't help but think about how far we've much this initiative we're calling GrassLands Brewing Company has evolved since its inception. While we don't have kids yet, I expect it's something like watching a baby grow. GrassLands is our baby and it's been incredible to watch it develop over the past 2 years.

Okay, okay...enough of that - let's get to the meat & potatoes of our educational outreach series we're lovingly referring to as "Back to Basics"! We've realized in planning this thing and talking about it (and talking and talking and talking about it), that there's a lot more to brewing than we're presenting as well as the jargon that goes along with it all. Take, for example, a conversation I was having with a GrassHopper just recently - I said something along the lines of "Yeah, it's all pretty simple, just step up your yeast starter and pitch when you hit 75." Does that sound like jibberish to you? If so, I sincerely apologize. This is the 91st post we've made and it's the first making an attempt to speak to you, my dear readers, in an easily understandable way about significant components that go into the brewing process. So, with that said - CLASS IS IN SESSION! Bueller? Wake up back there!

*Before we get started, if you finish this article and have more questions/concerns/thoughts - please leave us a comment and we'll address it promptly!*

Our first GrassLands class: Yeast 101. 

Yeast. What is it? Essentially, yeast is alive. They are millions of little cells that are really hungry and really, ahem, eager to rabbits. Yeast is integral to producing craft beer. In fact, it's one of the four critical ingredients in making beer. Broaden your knowledge! The four critical ingredients are:

  1. Water
  2. Yeast
  3. Malted Barley/Grain
  4. Hops

That's it! Well, not really, there are a ton of other adjuncts you can utilize to make great, innovative beer. In fact, many of our beers happily color outside the lines of those four components above. But back to yeast.

Yeast is critical to brewing great beer because without it, you'd have hopped up, malted sugar water (called wort - pronounced wert). Unless your main goal is to make malt syrup, this is just a stepping stone on the way to making beer. Yeast is infused after the boil process of brewing, once the wort has been cooled to around room temperature (for lagers, it's more like 45 degrees). That's when the magic happens. All those complex sugar strains are attacked by the millions and millions of yeast cells that have been introduced. In the most basic terms, think about it this way:

  • Yeast cells eat most of the sugars in the wort
  • Yeast cells fart off CO2 and leave behind alcohol 

This whole process is amazing to watch, by the way. That's why first-time homebrewers are almost glued to their fermentation vessels watching the Yeast Party that's commencing. With nothing left to eat, the yeast then begin to go dormant and succumb to gravity - settling down to sleep or slowly pass away in a cake on the bottom of the fermenter. This stuff, called slurry is usually collected, rinsed and re-used by the brewer for another batch in the future. Not only is this a practical way of saving money for a craft brewery, it's a means to analyze how yeast evolves from batch to batch. The big boys like Sierra Nevada, New Belgium, Stone, etc. all have very, very comprehensive yeast laboratories - ensuring that consistency from batch to batch is met. Crazy scientific stuff, eh?

On the smaller, pilot-batch brewing scale (like us), I wanted to give you a walk-through of a really important part of preparing for a brewday - and that's creating a Yeast Starter. In the 4 ingredients listed above that are critical to brewing beer, yeast really should be in bold because not only do you need yeast, you need healthy, active yeast. Easiest way to ensure you've got healthy yeast? Give 'em a head start! Basically, a yeast starter is a mini, unhopped beer. You give the yeast a chance to reproduce themselves on a mini-batch of beer 24-48 hours before your brewday. Then, once you're ready to pitch (or infuse) your yeast, you've stepped up (or multiplied) your yeast count - aiding in a healthy, active fermentation.

So - here's how this brewery in-planning makes its yeast starter, which we do for just about every batch:

1. Get your ingredients together: You need yeast (of course), dried malt extract (basically dried up wort), a pot, a stove, and something to stir.


2. Boil/simmer your malt extract - mixed with 2-4 pints of water (based on how large you want your starter to be - a good rule of thumb is 1000 ml per 5g batch, but do your HW ahead of time to see if you want to under/over pitch your yeast) - for 10-15 minutes....and Voila!  You've got wort!


3. Once 10-15 minutes pass, you've gotta bring your wort down to room temperature. Easiest way to do this? Give it an ice bath in your sink. This typically takes around 15 minutes or so. My suggestion, stir the wort the whole time as moving liquid will chill faster than still liquid. All you need to do is bring it to room temperature, so check the temp with a food thermometer.


4. Then pitch the yeast into your mini fermenter with the cooled-down wort, cover it with aluminum foil or something of the sort and...


5....if you can, put it on a stir-plate. Stir-plates are awesome because they add in another critical component in making healthy yeast: oxygen. The vortex created by the yeast/wort mix spinning around infuses oxygen on a continuous basis. Yeast need sugar to reproduce and be happy - they also need oxygen. If you don't have a stir-plate, do your best to swirl the yeast around every now & then so that a little oxygen gets into the mix. Bottom line, you'll have healthy, happy yeast when it's all said & done.

6. 24-48 hours later, pitch it into your wort with as much oxygen as you can and get ready for the magic to happen! It's a tedious process, but it's very, very important.

So now, my newly-educated readers, you know one of the major steps in producing great beer - or at least how we handle it at GrassLands! Like we said above, if you've got questions about yeast and the brewing process, leave us a comment below and we'll address it right away.

With that, have an extremely awesome weekend, my dear readers, because you definitely deserve it! We'll be back at it with a ton of brewing activity in the next month! Next week's Back to Basics topic: Building a Recipe! Talk at you later, folks!