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Yeast Harvesting: A Novel Approach?

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I began washing and harvesting my own yeast about a year ago. I got excited and harvested 4 jars from 4 batches in the first month, leaving me with 16 jars of 4 different yeasts. Since I usually brew twice per month, I had a ton of yeast just sitting in my fridge. After using some of this stored (aka old) yeast in beers that came out less than perfect, I began tossing it - hours of work, down the drain. Then I had an idea - why can't I just harvest clean yeast directly from my starter? After trying out a few techniques, here's the process that seems most efficient:
Step 1: Make a starter (3 days prior to brewing) that is .5 liter larger than you need for your beer. Since the majority of 5 gallon batches require no more than a 1 liter starter, a standard 2000 mL flask or even gallon growler will work great. In the photo below, I needed a 2 L starter for a 10 gallon batch, so I made 2.5 L.

Step 2: A couple days after making your starter, sanitize a 500 mL (1 pint) mason jar using the sanitizer of your choice. I prefer Iodophor.

Step 3: Fill the sanitized mason jar directly from the starter - if you use a stir plate everything will be in suspension, otherwise shake it up a bit prior to pouring.

As you can see, I poured about 500 mL of wort/slurry from my starter into the mason jar. After just a few minutes, you can already see the creamy white and very clean yeast settling to the bottom of the jar.

Step 4: Place the capped jar in the fridge over night to crash the yeast.
If you plan to use the yeast within a week or so, you can decant the "beer" and pitch directly from this jar. However, if you like to use different yeasts and won't be returning to your freshly harvested yeast for awhile, you will want to store it in a more hospitable environment. Steps 5 and 6 address how to do this.
Step 5: Fill a 250 mL (1/2 pint) mason jar halfway with tap water then microwave it (without the lid!) for 2 minutes to sterilize and de-oxygenate the water.

Remove the very hot jar and put the lid on (using pot holders... it's HOT!), then shake it up to sanitize the lid with the boiling water. Let this sit over night to chill to room temp. I usually do this right after harvesting my yeast from the starter.
Step 6: The next day, decant about 80% of the beer off of the pre-harvested yeast in the larger mason jar, making sure to agitate to release the yeast from the bottom of the jar. Then simply pour the yeast directly into the previously boiled water in the smaller mason jar.

Cap tightly and place in the fridge. Within a couple days you will have very clear water on top of a clean and compact yeast cake. When you want to use this yeast, make a starter as usual, decanting most of the water off the yeast, leaving just enough to help break up the cake.
Some of the benefits I see to this method include:
  1. The yeast is un-hopped and as clean as it's ever going to be. In fact, this is basically how White Labs and Wyeast grow their yeast.
  2. Since you're only making one jar of yeast, you won't have to store a ton of yeast (some people won't like this point).
  3. You don't have to go through the "washing" process, which is a pain in the arse if you ask me.
  4. You can brew any beer you want, even a barley wine or RIS, and still harvest yeast, as you're getting the yeast prior to it fermenting the beer you will ultimately brew. I guess you will need a pretty large flask, though.
I hope this helps. I've used the same strain multiple times very successfully. I'll never go back to washing yeast again.

Cheers!
 
Thank you Brulosopher for taking some of your valuable time to post that interesting tutorial.
I might have missed the most important point: For how long can you store that yeast cake ( under water ) in the fridge : weeks?, months? years ?
Best regards
Jacques
 
That is a good idea, and similar to mine. I have started to make 5 starters from one vial if Whitelabs. Personally, I think it works great. All my beers have taken off really well with this method. I brew two 12 gal batches at a time, therefore 4 carboys. Using this method, I have one left over to make more starters with.
 
Everything makes sense, except I don't get the point of transferring to the smaller jar. Why not just leave it in the first jar and decant the beer off the top, then pitch the yeast directly into a starter?
 
Not following the logic here. You say that you see the yeast settle to the bottom, but everything I've read says that TRUB is the primary sediment that settles to the bottom initially.
All other guides call for decanting the liquid above the trub into another jar, this liquid being full of yeast. Then, after chilling, the yeast settles out. Am I missing something? Yeast should take a decent amount of time to come out of solution at room temperature.
 
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  • #8
@eimar I'd stick with 4-6 months, though with a large enough starter I'm sure up to a year would work fine.
 
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  • #9
@BigB You can absolutely do that, I just prefer to leave my yeast under a bed of deoxygenated and sterile water if I don't plan on using it for a couple weeks. It's just a safety precaution... and it only takes a few minutes.
 
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  • #10
@nickmv A couple things... first, when you're washing used yeast, trub will most certainly settle to the bottom first, and rather quickly, hence the reason you'd let it settle for a few minutes then decant the beer off the top and proceed. However, with this method you are harvesting yeast from a purely malt (unhopped) starter that has a stir bar keeping everything in suspension. Given the fact the volume is so small, it's unlikely there is too much protein or lipids like you get in a 5+ gallon fermentation.
Second, the yeast I used in the demo was WLP002 English Ale, which is known for flocculating and dropping out quickly. This is mainly why you see the layer at the bottom. When I've done this with less flocculant strains (e.g., WLP001), it takes a few hours for the cake to form.
Cheers!
 
I think your metric to English volume calculations are off.
500 ml is roughly a pint (not 1/2 pint). Also, 250 ml is roughly 1/2 pint (not 1/4 pint).
Other than that this looks interesting. I used to wash yeast post-fermentation but stopped when I went to 10 gallon batches using a stainless keg. I may now start harvesting from my starters.
I just tossed a few washed samples that were 2 to 3 years old. They still looked and smelled o.k. but I didn't test for viability.
 
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@nickmv A couple things... first, when you're washing used yeast, trub will most certainly settle to the bottom first, and rather quickly, hence the reason you'd let it settle for a few minutes then decant the beer off the top and proceed. However, with this method you are harvesting yeast from a purely malt (unhopped) starter that has a stir bar keeping everything in suspension. Given the fact the volume is so small, it's unlikely there is too much protein or lipids like you get in a 5+ gallon fermentation.
Second, the yeast I used in the demo was WLP002 English Ale, which is known for flocculating and dropping out quickly. This is mainly why you see the layer at the bottom. When I've done this with less flocculant strains (e.g., WLP001), it takes a few hours for the cake to form.
Cheers!
 
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@RmikeVT Right on, man. I've been using this method for the past few months and it has been working fantastically. I've got a couple strains that are on their 4th and 5th generations, and they still get going like crazy, making great beer. Good luck! If you have any questions, don't hesitate to ask.
 
I've been doing the same thing with either yeast recovered from bottles of bottle conditioned beer or from a vial of White Labs yeast. But I take it one step further. I freeze the yeast for long term preservation. I just wrote an article on the process of freezing the yeast that was posted in the article section that is based on the approaches discussed in the thread on freezing yeast. Take a look.
 
Bravo. All I can say is, "why didn't I think of this?"
Seriously though, thank you very much! Can't wait to get going on it.
 
Wow! This is so simple and makes so much more sense than washing! Genius!
I just tried to do my first wash this weekend. After watching a lot of videos and looking at a lot of photos I couldn't tell if I was pouring trub or yeast. My thin white line was really, really thin, so after all that messing around I'm not sure anything is even viable. This solution seems so much easier and so much cleaner! I will definitely do this on my next starter! Thanks for sharing!
flips
 
Is there a benefit to doing this rather than making a "glycerol" stock and putting it in the freezer?
I've tried using malt extract instead of glycerol as a cryo-protectant and it seemed to work just fine. Had to grow up the starter culture days in advance though as I'd only made small aliquots.
 
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@bristela I'm afraid I'm nowhere near smart enough to provide a satisfactory response to this question... anyone else?
 
Brilliant. This is one of those "Why didn't I think of that?" ideas. I will have to try this following my next batch, in which I am using yeast harvested the old-fashioned way ;)
 
YES! I am about to make a starter for a brewday coming up. I think I may just have to pull some of this off and start saving my own "parent yeast" I live over an hour away from my LHBS and it would be nice to build a "library" of sorts in my beer fridge of commonly used strains.
Thanks for taking the time to do the write-up man! Appreciate it!
 
I'm confused by step 6
"decant about 80% of the beer off of the pre-harvested yeast in the larger mason jar, making sure to agitate to release the yeast from the bottom of the jar. Then simply pour the yeast directly into the previously boiled water in the smaller mason jar."
Is the 80% discarded and the remaining 20% poured into the boiled water? If so, why would you agitate the yeast during decant? Wouldn't this mean that you're discarding a large percentage of the yeast?
 
Genius! I never thought washing the yeast after a full fermentation was a good idea, inbreeding over too many generations and all.
 
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@LeroyWhite Before agitating, pour off (decant) about 80% of the basically clear beer sitting on top of the yeast, then agitated the jar just to remove the yeast from the bottom... it's sticky stuff ;)
 
Awesome!!! I have about 12 1/2pint jars in the back of the fridge holding multiple jars of washed yeast from 3 strains. SWMBO was a bit iffy at me taking up so much room in the fridge, but taking this approach will definitely cut down on the necessary fridge space to keep my growing library :) Thanks, Brulosopher!!!
 
I did this for the first time today and before I got the yeast going I went to the local hardware store and bought a pack of the pint mason jars. Now I have a bunch of these and was wondering if it is really necessary to now go buy 1/2 pint mason jars as well. I would really rather be able to use another pint jar for the 6th step if possible to save on costs.
 
Great post, thanks! One question I have is how can we determine how many billion cells are in that 500ml slurry? We know one vial or smack pack normally range from 100 to 130 billions.
 
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@Bisco_Ben Nah, it's not really necessary. In fact, I just harvested from 2 smaller jars then combined them a couple day later with the boiled water. Worked great!
@Royale I really have no clue how you'd get an accurate cell count without using some sort of really nerdy lab equipment... which I kinda wish I had... but alas...
 
Brulosopher - good stuff. I have saved some starter yeast before and also washed (well sort of) before too. I like your process and will start doing this for the next batch.
 
How about this??? Make the big "1st generation" starter (say 1.5 liter), pitch half to new wort, refill starter flask with saved new wort made that day, 2 days later harvest about 4 jars of "2nd gen"...over time, use 3 and when get to 4th, do this again and harverst 4 jars of "3rd gen".
I've been harvesting/washing yeast for a while but worry a little about generations as I've read things can start to stray in 4 or 5 gens. (that said I've yet to detect any issues)
Thoughts?
 
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@onthedot Yep, easy-peezy
@Brewsday Sounds good to me, do it and report back. I don't like having all the yeast lying around, so 1 jar is good enough for me.
 
A pretty well written tutorial but I would be a bit concerned about the dangers of superheated water in microwaves.
Perhaps an alternative of boiling water and then put into a ehrlenmeyer flask and foil capped separately from cleaning/sanitising the mason jar would be safer?
http://en.wikipedia.org/wiki/Superheating
http://chemistry.about.com/b/2012/01/14/the-myth-about-superheating-water-in-the-microwave.htm
 
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  • #37
@MaltyHops - Very, very good point. In fact, I've experience the superheat phenomenon and it's scary. For those concerned about it, I think your recommendation is a good one. For me, I'm comfortable with my current process. Another option is to put a wooden stir stick in the water when you put it in the microwave. Thanks!
 
Well I am here to report that I tried this method and so far it is a success!
I am making my first starter with harvested-yeast. I am making this one 500ml larger so I can continue to harvest yeast perpetually :)
Is there a point when yeast has been over-harvested?
 
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