Sunday, June 24, 2012

Identifying Washed Yeast - What To Look For

I've learned a lot about yeast this year, a lot more than I knew even a year ago. Since I started washing and reusing the yeast I use to ferment my beers with I've discovered how to identify some of the different strains too. Yesterday after bottling a batch of Mr. Beer/Coopers Bavarian Weissbier, washing the yeast and putting the mason jars in the mini-fridge where I store my yeast strains I saw 6 jars of yeast that I had forgotten to label.

Screwy's 420 Special American Wheat
You've been there too I'm sure where you put something off thinking I'll do it later while I still remember and then days go by and surprise you have no clue which was which. Well fortunately after being in the refrigerator for at least two weeks the yeast had stratified into very distinct layers and the order that the layers were stacked made it fairly easy to tell the strains apart.

Left To Right ECY-12, WLP-001 And WLP-400
The two unlabeled strains were White Labs WLP001 - California Ale Yeast™ and East Coast Yeast ECY12 - Old Newark Beer™ with the WLP-001 being a top fermenting 68-73F ale yeast and the ECY-12 being a bottom fermenting 53-68F lager yeast. As you can see the fermentation requirements and characteristics of these two strains are very different and mixing up the temperature ranges would really produce some uncharacteristic flavors for either strain.

ECY-12 With Trub Layer Under Yeast
As it turned out the jars containing the WLP-001 yeast stratified with a thin layer of trub lyiing on top of the creamy white layer of ale yeast. With the ECY-12 the trub layer was clearly visible underneath the the creamy white layer of lager yeast. Luckily I had taken the time to label several other jars of WLP-001 and ECY-12 from prior batches so I had them to use as a comparison. The end result enabled me to label three jars as WLP-001 and the remaining jars as ECY-12, now I'm feeling a lot more organized and secure in the fact that my next fermentation will be done using the right yeast.

WLP-001 With Trub Layer On Top Of Yeast
As of this posting the WLP400 - Belgian Wit Ale Yeast™ has still not completely stratified the less flocculant cells are still in suspension after a week in the refrigerator. Already clearly visible under the yeast layer is the trub layer which consists mainly of proteins and dead yeast cells. In all instances the creamy white layer is the yeast layer and no matter how you proceed from here in using the washed yeast it is this layer that really matters.

WLP-400 With Trub Layer Under Yeast
If you decide to decant the washed yeast slurry too soon before the layers have completely finished stratifying you will undoubtedly pour off some of the least flocculant cells which are key to getting the maximum attenuation during fermentation. I have a dedicated mini refrigerator that I keep all my yeast jars in and it doesn't get opened too often which is a good thing. I've used my washed yeast to make a starter after storing it there for six months and the beer it made was great.

Money For Nothin' And Your Yeast For Free!


  1. This is an interesting discovery. I usually have kept my yeast in growlers so have never really taken the opportunity to see what they look like when they are at rest. I think it may be time to move into some mason jars so I can get a better look at them.

  2. Washing my yeast saves me some coin but it's all about the science of brewing it's Rocket Chemistry!

  3. Great article, very informative for home brewers

  4. The benefits are many you first learn how its done then how to fit the process into your existing brewing schedule and start saving money by always having a fresh supply of your favorite yeast on hand.

    It's a definite win/win situation and in the end you have better tasting beer and that's always a good thing.