Author Topic: Harvested yeast  (Read 9138 times)

Offline ned

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Harvested yeast
« on: November 22, 2016, 09:34:43 AM »
I have a question about reusing harvested yeast. I've scoured the internet, searched forums, and used a variety of calculators and calculations and I'm still unclear/confused. Here is the situation. I have about 40ml of yeast cake that is pretty clean. I'm going to use it on a double IPA with an OG of 1.080ish. My question is, about how many viable yeast cells do I have (harvested 11/11/16). Target pitch rate is about 275 billion. Would a two liter starter do the trick? No stir plate, I shake every so often. This is my first time attempting to reuse yeast. Thanks for any feedback!

Offline Oginme

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Re: Harvested yeast
« Reply #1 on: November 22, 2016, 09:54:52 AM »
In a ml of yeast there are about 4 to 4.5 billion cells.  This is a pure yeast cake like you would find in the bottom of a White Labs yeast vial.  If you have a slurry, you need to determine how much is water/wort vs yeast.  Most of the time, to get a yeast slurry to flow it ends up being about 25% yeast. so figure that every ml of yeast slurry collected contains about a billion cells.  If you have about 40 ml of pretty clean yeast, you can figure on having about 40 billion cells.  You can discount this if you feel you have any significant amount of trub mixed into the yeast by whatever % of trub you think you have.

If you use the yeast starter in BeerSmith (or any other for that matter) what I do is define a unit of yeast as being 1 ml and having a yeast count of 1 billion cells.  I can then set the date to the date I collected the slurry and the number of units to the number of ml of yeast I have harvested and BeerSmith (or any other good calculator) will give me an estimate on the viability of the cells.  You can then use the recommendation from BeerSmith to get a starter size for the volume and gravity of your DIPA from that.

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Offline jomebrew

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Re: Harvested yeast
« Reply #2 on: November 22, 2016, 10:44:22 AM »
If you have done starters from a while labs vial, then you can estimate the cell count based on the size of the harvested yeast cake. 

I have never used a starter on harvested ale yeast.  These yeast are already healthy, likely a good cell count and ready to get into the action right away.


My process and experience is below.


I use harvested yeast often.  My process is to boil then cool to 60F 1 liter water in a 2 Liter Erlenmeyer flask loosely covered with foil.  Xfer yeast and trub from a previous batch adding about 500ml -1 liter.  Foil only comes off during the xfer.

In a 1 Liter Erlenmeyer  flask, I boil 500 ML water covered loosely with foil and cool to 60F.   

I slowly decant off all the liquid in the 2 liter until the yeast start to escape.  I let it settle for 15 - 30 minutes then slowly transfer the yeast into the 1 liter. Once trub starts to transfer, I stop.   

From the 1 Liter flask, I decant off the water and pitch the rest into 5.5 gallons of wort.  I do this for Imperial IPAs, Imperial Porters and Barleywines.  I have excellent fermentation and complete attenuation.

My brew on Sunday, I used a siphon cane and transferred 750 ML of the yeast/trub cake from a porter I brewed a week ago into a flask, let it settle at round 60F (garage temp) for a couple hours, decanted off the beer and pitched about 100ML of the harvested yeast/trub into 1.071 gravity  IPA wort.  When I checked the next morning, fermentation was going well and had been rocking since yesterday afternoon.


Offline ned

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Re: Harvested yeast
« Reply #3 on: November 22, 2016, 01:45:56 PM »
Thanks for the feedback. The yeast is in pint jars with ml marks on them so I'm relatively certain about having 40 ml of almost clean yeast cake. About 1 billion cells per ml is about what I was thinking but I've seen estimates of 2-3 billion and mr malty calculates at up to 4.5 billion. Thinking I'm going with a two step starter from 1L to 2L based on a guess that I'm starting with 40-80 billion cells viable cells.

KellerBrauer

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Re: Harvested yeast
« Reply #4 on: November 22, 2016, 02:16:53 PM »
Greetings All,

I have been intrigued for some time about the concept of washing and harvesting yeast.  So I followed my curiosity and landed on Scott Ickes website where I found a very detailed and well presented instruction on his process of washing and harvesting yeast.  I'm still very impressed with the process.  But I must ask, is it worth the work and aside from saving some money on brewday, does it really pay off?  Perhaps that's a question for another thread.....just wondering.

Happy brewing!!!

Offline jomebrew

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Re: Harvested yeast
« Reply #5 on: November 22, 2016, 02:37:04 PM »
But I must ask, is it worth the work and aside from saving some money on brewday, does it really pay off? 

Personally, I like the beer better on the 3rd generation and later.  I've done 6.  My current pitch started with 1 pure pitch in a  Brown Ale then to the Imperial Porter and now to the IPA. I'll harvest from the IPA in a couple weeks for a DIPA the probably a Barleywine in Jan.

KellerBrauer

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Re: Harvested yeast
« Reply #6 on: November 22, 2016, 02:44:15 PM »
Thanks jomebrew for your fascinating reply. Are you suggesting the yeast improves, or somehow changes, as you use it?  If that's the case, than I need to further my research.
« Last Edit: December 02, 2016, 09:25:59 AM by KellerBrauer »

Offline twhitaker

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Re: Harvested yeast
« Reply #7 on: November 22, 2016, 03:45:03 PM »
 I have done lagers with 5 reused generations of saved yeast. If you are very careful not to get trub into the fermentor, you will have a really clean resulting yeast cake after fermentation. I swirl it and pour into sterile pint or quart mason jars. I will start the next one a few weeks later using one pint yeast slurry ( half a quart jar) to 12 gallons of fresh wort, fermenting at 5- 10 c (40-50f).  No need for starters or washing. Starter is for first pitch with new yeast. Overpitched i'm sure but works well for up to 5 generations with cold lager fermentation. Starts chugging away within an hour. Trick is to only put clear trub free beer into the fermentor, using whirpool settlement, irish moss in the boil, a bazooka screen in the boil kettle outlet and stopping transfer before trub enters.
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Offline Oginme

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Re: Harvested yeast
« Reply #8 on: November 22, 2016, 04:33:17 PM »
My maximum so far is 8 repitches of harvested yeast.  My average is around 4 pitches.  I agree pretty much with Tom on the clean yeast cake and for some of the heavy flocking yeasts I end up doing a repeat rinse with pasteurized water to get a clean, mostly trub-free yeast cake to continue pitching.

Generally, I find that the 3rd through 5th or 6th pitch is pretty good.   Beyond that, the amount of either mutations, wild yeasts, or other bacterial contamination starts to degrade the consistency of the yeast strain.  If it has some specific characteristics, they will seem to fade out. 

I try to grab a good sample after pitches 3 or 4 and plate it out to preserve it for growing back up in the future.  So far (knock on wood), the plates have shown clean yeast at this point with no colonies which are non-yeast. 
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Offline ned

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Re: Harvested yeast
« Reply #9 on: November 22, 2016, 07:01:17 PM »
So is the suggestion that I can pitch the amount of yeast slurry shown in the attachment into a 5 gallon batch OG 1.080 without a starter and be ok?

Offline jomebrew

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Re: Harvested yeast
« Reply #10 on: November 22, 2016, 07:52:52 PM »
So is the suggestion that I can pitch the amount of yeast slurry shown in the attachment into a 5 gallon batch OG 1.080 without a starter and be ok?

I would after decanting the water/liquid.


Offline ned

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Re: Harvested yeast
« Reply #11 on: November 25, 2016, 07:41:44 PM »
I ended up stepping from 1L to a 3L starter. Brewing Sunday.🍻

Offline ned

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Re: Harvested yeast
« Reply #12 on: November 28, 2016, 07:07:06 AM »
So here's the current situation. I stepped up from a 1L to a 2.5L starter on Saturday morning using the harvested yeast pictured in this thread. No stir plate, so I shook and swirled as often as possible like usual. Fast forward to Monday morning and there is still a huge head of krausen on top bubbling away. I've never had a starter this active for this long. I'm sure it's fine but I was just wondering if anyone else has had this and what might be causing it? Did I accidentally make to strong of a starter? It was my first time making my own wort. I've always used fastpitch cans up to this point. I followed Palmers 2 cups water to 1/2 cup DME guideline.

Offline ihikeut

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Re: Harvested yeast
« Reply #13 on: November 28, 2016, 07:08:30 PM »
It's fine, relax and have a home brew. Yeast determines when it's done fermenting, may take a week or two.


Offline Oginme

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Re: Harvested yeast
« Reply #14 on: November 29, 2016, 05:42:03 AM »
Especially since you are using a 'shaken, not stirred' starter method it may take a bit longer for the yeast to fully exhaust the food supply.  When not agitated back up into the slurry, much of the yeast will end up flocking and settling to the bottom.  Once flocked, it takes quite a bit of agitation to get the flocks to break up and disperse.  This slows down the reproduction rate.
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