More with Less Part. 1: Yeast
If you have been homebrewing long enough, you have probably realized by now that you could save a lot of time and energy not homebrewing. Essentially, homebrewing is work; if you’re doing it right, it’s very rewarding work. I have a hard time thinking of something I would rather spend my day doing than refining a tried-and-true creation or bringing a new recipe into the world.
If I learned anything from the years I spent getting my Bachelor of Arts (and the subsequent post-graduation years of “finding myself”) it was how to make more with less. This usually means more work and planning. However, when it’s something as enjoyable as brewing, a little time and a little more work simply means more to enjoy.
In the first part of this series of articles I would like to talk about something I have been doing for some time, and have had great outcomes with—reusing yeast.
You Can Re-Pitch That!
Like many aspects of brewing, there are a variety of ways to approach yeast re-pitching, depending on your time and financial dedication. The simplest ways of reusing your yeast come in the forms of pitching onto the yeast cake and top-cropping from a primary fermenter.
After your primary fermentation, that gunk and sludge at the bottom of your bucket/carboy/shiny-all-stainless-Blichmann-Ferminator-conical contains billions of living yeast cells ready to keep the party going. Why not use them? If you plan your brew-days, you can brew a new beer to pitch onto that slimy living cake as you transfer the other beer. I have had great success doing this, but there are a few things to keep in mind.
Generally you want to start out with a lighter in color, less hoppy, and less alcoholic beer, and brew a strong beer onto the yeast cake. The reasoning behind this is that a lot else is left behind in that cake than just living yeast. If you start with an 8% ABV. Black IPA and re-pitch a Cream Ale onto the cake, chances are the Cream Ale is going to end up darker in color, more bitter, and could present some stressed out yeast flavors, such as plasticky phenolics or an ethanol burn. This is because there are remnants of malt proteins, spent hop matter, and, in a beer 7% ABV. and up, some stressed out flabby old yeast. I typically plan my beers in pairs, with a small beer to start with, then brewing a double-sized beer and reusing the small beer yeast. One thing to take note of: if you wanted to brew several similar moderately alcoholic beers with the same yeast, I would recommend using about half of the cake as using too much yeast can also stress out the yeast. I “cut the cake” like this several times with a series of Pale Ale and have had no perceivable ill side effects. While this method may not be the most scientific or sophisticated, with a little consideration, it can work very well.
Another method of yeast collecting is through top-cropping. Top-cropping can be done with ale yeasts, and works especially well with yeasts described as “true top-cropping strains.” These yeasts form a large krausen on the top of the fermenting wort. This krausen is full of thriving, hungry yeast that can easily be scooped up with a sanitized pint glass to be reused. This method obviously does not work with fermenting in a carboy, and though it may work to add this directly to another wort ready to ferment, it would be a good idea to make a yeast starter to bulk up your yeast count before repitching.
Washing It Down
It’s super simple to rinse your yeast to allow it to store better for use down the road. Yeast collected with the trub from the bottom of the primary fermenter needs to be separated from the rest of the gunk in order to store and stay viable. At this point, all you need is a couple of large, sanitized mason jars and some distilled (or pre-boiled, then cooled) water.
Take some of your yeast trub from your fermenter and pour it into the first mason jar. It’s preferable that it’s a little liquidy in order for it to separate better, so adding a small amount of distilled water could help you out. Stick it in your fridge, and after 30-60 minutes you should be able to see some clear separation. There will be three layers: water on top, tan yeast in the middle, and trub gunk on the bottom. Decant the yeast into your second sanitized jar, trying to leave all the trub behind. Repeat the process until no trub can be spotted (usually 2 or 3 times). This yeast can then be stored in the jar for up to two months, and then can be used in a yeast starter to get it going.
Yeast is an amazing, living organism that will gladly do your bidding if you take care of it. If you have any questions, feel free to ask us at O’Connor’s and we’ll do our best to answer. Some great articles to check out on yeast reusing can be located at BYO (http://byo.com/scottish-ale/item/739-harvesting-yeast-techniques) and on the BeerSmith blog (http://beersmith.com/blog/2008/07/25/yeast-washing-reusing-your-yeast/). For more incredible, in-depth information, pick up a copy of Chris White and Jamil Zainasheff’s Yeast book available at O’Connor’s.
Andrew DeHaan, Home Brew Expert firstname.lastname@example.org