Best yeast washing procedure for harvesting lager yeast.

[knollybru]

I have a Pilsner that I am about to keg and would like to harvest the yeast to use at a later time. I’ve washed yeast before a long time ago but wondered if the effort was worth it. Does the fact that it’s a lager change the amount I should try to get?

Any advice is appreciated. What do you all do?

It’s about a 1.050 beer
Yeast is Imperial Global strain

 

[Robert65]

Rinsing yeast is one of the most harmful things you can possibly do to it. This practice apparently just won't die among homebrewers, rooted in outdated misunderstandings and misinformation parroted by old homebrew books. Yeast should always be stored under the beer it made until it is repitched. Just leave enough beer when racking, then swirl up the slurry in your fermentor and save in a Mason jar or other container of choice, loosely covered. A good rule of thumb when pitching lager yeast for cold fermentation is to pitch about half the slurry from one batch into the next. For warm ale fermentation, a quarter.

 

[bracconiere]

Rinsing yeast is one of the most harmful things you can possibly do to it.

good to hear.....i just scoop it up into a tupperware container, and throw it in the fridge......

 

[madscientist451]

After you rack off the beer, just swirl up the remaining beer/yeast slurry and dump it into a sanitized quart jar. Depending how much you have, and how long 'till you brew again, either use half of it or the whole thing in the next batch. I've kept lager yeasts going for several years using this method.

 

[Sauls]

Interesting, But why only half? I would assume there would be some trub in with the yeast. Unless the intent is to dump that off as they separate in the fridge.

 

[downzero]

Interesting, But why only half? I would assume there would be some trub in with the yeast. Unless the intent is to dump that off as they separate in the fridge.

Because yeast multiplies as it ferments, so you have more yeast cells when you're done than when you started.

Best procedure I've found is a mason jar and a sanitized soup ladle.

I also don't think overpitching matters so I probably pitch more yeast than some would think necessary.

 

[RPh_Guy]

Yeast should always be stored under the beer it made until it is repitched.

"Always" is maybe too strong of a word.
A good case could be made for isotonic saline based on available data. And FWIW Kunze recommends storing yeast with some fermentable sugars remaining.

Interesting, But why only half? I would assume there would be some trub in with the yeast. Unless the intent is to dump that off as they separate in the fridge.

Over-pitching can lead to an unhealthy fermentation. Also the cake contains a relatively high percentage of dead cells, which you don't want to re-pitch.

 

[Conehead]

I thought that you can't " over pitch " a lager.

 

[Paulaner]

"
Also the cake contains a relatively high percentage of dead cells, which you don't want to re-pitch.

Is this what you're seeing under the microscope? I consistently see 100% - 99% viability for each re-pitch, I've also talked with others that scope their yeast who see the same.

 

[RPh_Guy]

Is this what you're seeing under the microscope? I consistently see 100% - 99% viability for each re-pitch, I've also talked with others that scope their yeast who see the same.

I don't have a microscope.

You're claiming yeast cells don't die in significant quantities, or am I misunderstanding what you're saying?

I've read lots of scientific sources showing that yeast viability starts declining toward the end of the stationary phase and then the rate of declines jumps significantly from the end of fermentation and continues fairly rapid decline throughout storage under beer.

I can post some sources if you want. You've read Kunze, right? It's in there. .. and we know this applies regardless of brewing scale because liquid homebrew yeast packs (stored in optimized growth medium / beer) are well-known to lose viability over time.

 

[Moose_MI]

I want to be able to store yeast for 6 months and make a 4 liter starter and pitch into 15G of 1.06 wort. I use whirfloc and hop bags so my slurry is reasonably clean but I dont have a conical that allows me to drop trub.

Ive always “rinsed” yeast to try to leave the trub behind. I probably add 1-2 quart of boiled water that i split across the 3 fermenters of my 15G batches.
All i want is to have something that I can pitch into a 4 liter starter at 6months and ferment 15G of average gravity beer.

Am i doing it wrong? It’s worked for me so far but I’m open to suggestions based on facts..especially from personal experience. I dont need people repeating dogma

 

[bierhaus15]

I used to look at yeast viability numbers daily for a very large brewery and would rarely see 99-100% viability in harvested slurry, even for the most dialed in fermentations. For home brew collected yeast, it's more like 70-90% and bottom collected slurry harvested from a beer that was on the yeast cake for weeks is typically lower than that. It is common to see around 10-20% reduction in viability for each month the slurry is in storage, especially at temps above 40F. At temps close to 32F, an extremely healthy slurry will see little reduction in viability until it runs out of glycogen and trehalose, ect, but there can still be fermentation issues. Most breweries only store yeast slurry for 1-2 weeks and some only for 24 hrs. The things that kill yeast viability are time, temperature (>40F), oxygen exposure, and poor yeast nutrition; like harvesting from a less ideal fermentation.

And while yeast from an old yeast slurry will eventually start fermentation, there will be fermentation issues;
slow attenuation, poor yeast growth, high SO2, high acetaldehyde, diacetyl, ect. On the surface everything looks fine but problems are unavoidable.

A better method of storage, IMO, is to selectively harvest yeast via a conical or by selecting the top portion of the yeast cake to avoid trub. When possible, top crop ale yeasts. Store this yeast either directly under the beer it fermented for use within a week, or use a dilute solution of sterlized water and the same beer for more than a week. Anything stored longer than a month gets tossed out or a portion thereof is used in a yeast starter to grow it back up.

 

[Paulaner]

So the number I'm seeing aren't that because I'm a home brewer? Who leaves their yeast in the fermenter for weeks, Ale is roughly 2-2.5 days, lager 4-4.5 days. Also, if you don't transfer any trub to the fermenter you don't have to worry about it while harvesting the yeast. I think the longest I've waited for a fermentation of harvested yeast to start up is about 4 hours, the FFT is usually kicking in less than 1.

 

[McKnuckle]

Who leaves their yeast in the fermenter for weeks, Ale is roughly 2-2.5 days, lager 4-4.5 days.

Judging from what I read on HBT routinely, I'd say lots of people, even most. Those timings you note for yeast removal are not realistic or even desirable for any style of beer. Unless I am missing something in translation?

 

[Paulaner]

Not realistic? Start fermentation usually at 1.048 transfer to spunding keg with 4 points of gravity remaining from where I want the beer to finish. So my FFT typically is 1.007-.08 and I leave depending on the style roughly .002 points in the beer. So my terminal gravity target would be 1.010, once I'm at 1.014 I transfer to spunding, Ale 2-2.5 days or Lager 4-4.5 days. Then I harvest the yeast for brewing the following week. I'm not taking a dig at anyone here I just am lost, maybe I don't understand something or am not clearly communicating what my procedures are, but this fermentation timeline is pretty common in professional breweries, aka not most micro breweries that produce crap beer.

 

[bierhaus15]

Those fermentation times are pretty normal for most breweries, although tank times are often longer. Generally they are off the yeast within a week. And you may be seeing 99-100% viability in your slurry if harvesting that early, although the average home brewer who is leaving their beer on the yeast for 2-3 weeks is not going to see anything remotely close to that. And that's before storing for 6 months.

And this is a discussion for another day, but per float tanks and clear wort, most of the larger German breweries are phasing that out as separation technology has improved by leaps and bounds since the days of Narziss and Kunze; more fatty acid wort content from trub is better for fermentation health and the health of yeast on repitching. German breweries now trying to achieve more trub in their fermentation tanks, ect, ect.

 

[Robert65]

Agree with @Paulaner. Kunze, for instance, says that lager yeast that does not ferment to final gravity (save ~0.5% residual extract required for spunding) in 4-5 days should be discarded and not repitched. This is my experience as well, lagers should finsh in that timeframe, and ales be completely fermented out in about 60 hours at most (as is typical in British breweries.) I have never been able to comprehend the reports of homebrewers taking many days or weeks to complete fermentation, but they must have multiple, serious, fundamental issues to address.

 

[Bassman2003]

I want to be able to store yeast for 6 months and make a 4 liter starter and pitch into 15G of 1.06 wort. I use whirfloc and hop bags so my slurry is reasonably clean but I dont have a conical that allows me to drop trub.

Ive always “rinsed” yeast to try to leave the trub behind. I probably add 1-2 quart of boiled water that i split across the 3 fermenters of my 15G batches.
All i want is to have something that I can pitch into a 4 liter starter at 6months and ferment 15G of average gravity beer.

Am i doing it wrong? It’s worked for me so far but I’m open to suggestions based on facts..especially from personal experience. I dont need people repeating dogma

I would like this as well but it seems time periods longer than 1 month create negatives. How negative is up for interpretation. If many cells die over the 6 month storage then there is not much to be gained vs buying a fresh pitch. Also, if you chance poor fermentation performance then that is not ideal either.

 

[McKnuckle]

I appreciate that pro breweries are able to control fermentation just so. But homebrewers who can do that are few and far between. Case in point; I am monitoring a Helles that's fermenting in a keg right now, trying to determine when to attach a spunding valve.

It's only 2.25 gallons, 1.045 OG, and I pitched a whole 11g pack of W-34/70 at 51 degrees. It's been glugging away steadily into a blow-off jar for 6 days now. I just tapped it to grab a hydro sample, and... it's at 1.026. In six days. I am expecting an FG of around 1.009.

So this is why I made my observation. Perhaps someone is able to move lager off the yeast in 4 days, but it ain't me.

 

[RPh_Guy]

@Paulaner
There's a disconnect between the ideal processes you're using and the processes used by most homebrews. I was responding within the context of the latter. @bierhaus15 pretty much nailed it.
The vast majority of home brewers will be seeing a much larger percentage of cell death than you are.

they must have multiple, serious, fundamental issues to address.

Indeed.

 

[Moose_MI]

I’m going to toss this out there..no science to support it just what I’ve done..

Any slurry (rinsed, washed, or neither) that I’ve saved is useful as-is for 1 week (maybe 2) at the most w/o having to make a starter. I rarely brew within a couple weeks so I’m always making a starter because I believe strong, active, healthy yeast are super important to good beer. Would the yeast ferment without a starter...yes, but my experience has been that it’s never as good a beer in the end.
I’ve found my “rinsed” yeast do better in a 4L starter than if I just save the slurry as-is and make the same starter. On average I’d say this is yeast Ive saved for 2-3 months. I’ve used 6 month old but i built it up with a 1 liter..then a 4 liter starter. Again, I’m doing 15G batches so it’s still worth the $$ in DME. Understand where most would say it’s not worth the time and no argument there. It’s just what I choose to do.

 

[Bassman2003]

So you take the yeast from a batch and then make a 4L starter and store the starter for 2-3 months? Do you then decent and pitch or do any more starters before the next brew?

 

[Moose_MI]

No...i rinse the yeast from 3 6G fermenters and store for 2-3 months...as long as 6....and always make a 4L starter before I pitch into next batch. If it’s closer to 6 month then I do 2 step starter.

I guess I’m making 2 points......in my brewery I “rinse” yeast because I think it’s improves yeast health 2-or 3 or 6 months later when I go to make a starter. The 2nd point is that if you’re making a healthy starter then I dont think the cell counts, viability, vitality, age, etc etc really matters. If the starter takes off then I’m good...if it doesn’t then I start fresh.

I’d love for someone to tell me they save slurry an pitch after 2-3 months w/o starter and it makes good beer......but I dont think that’s what happens.

So...in summary....my opinion.....within reason, you can save yeast however you want .... the real magic is in the starter...that’s where you’re really building the yeast that are going to ferment your beer.

 

[Bassman2003]

Thanks for clarifying. Yes, a large starter at the end of a long storage would increase cell counts to make up for the losses. The quality of the fermentation would need to be tested or at least is subjective. If the rule of thumb mentioned earlier in the thread was to pitch 1/4 of a slurry for ales, then a long storage period might have enough living cells in the end if more or all of the slurry was used for one batch.

I am 50/50 on this compared to just buying a fresh pitch. If you are only brewing this beer once every three months and also making a starter anyway, the cost savings are not that large. It is yields more yeast or better flavor, maybe, but I would expect debate on this.

 

[keesh]

I can post some sources if you want. You've read Kunze, right? It's in there. .. and we know this applies regardless of brewing scale because liquid homebrew yeast packs (stored in optimized growth medium / beer) are well-known to lose viability over time.

how did you get your hands on the Kunze? When you mentioned it and it garnered replies here, I became intrigued by this seeming legendary tome's status in brewing culture. Now I am saddened that I might never lay my hands on it. I cannot find the ebook anywhere and used copies are 150+.

A good case could be made for isotonic saline based on available data.

Do you have a recipe for an isotonic solution for yeast cells? Or is it the same 0.9 used in the medical field?

edit: I found this post https://www.homebrewtalk.com/forum/threads/simple-yeast-banking-with-sodium-chloride.662787/page-2 are your opinions the same then as it is now?

 

[RPh_Guy]

how did you get your hands on the Kunze? When you mentioned it and it garnered replies here, I became intrigued by this seeming legendary tome's status in brewing culture.

I got the latest 6th English edition (it's a new translation, not so much a new addition) from the MBAA. Look like they increased the price of it since then.
http://my.mbaa.com/ItemDetail?iProductCode=90826
Indeed it's expensive, as it's a textbook.

Do you have a recipe for an isotonic solution for yeast cells? Or is it the same 0.9 used in the medical field?

Right, 9g/L NaCl in water.

edit: I found this post https://www.homebrewtalk.com/forum/threads/simple-yeast-banking-with-sodium-chloride.662787/page-2 are your opinions the same then as it is now?

Isotonic saline is a good method for yeast banking. It's probably not a good method for storing large cultures. Mentioning it here was admitedly a little pedantic.

 

[Moose_MI]

Yes, a large starter at the end of a long storage would increase cell counts to make up for the losses.

How do you define “long storage”? For me I found after a coupe weeks fermentation can be compromised w/o a starter and I would imagine that this would be magnified in a lagger fermentation. I see a lot of posts about yeast washing and I’m assuming in the majority of cases folks are intending to be saving that yeast/slurry for more than just a couple weeks. I’m suggesting that you can likely use any number of yeast washing/rinsing processes or simply save the slurry.....the more important question is what are you doing to make sure that when you take that saved yeast out of the fridge you are taking the steps to make sure that you’ve got quality and quantity of yeast to ferment your next batch. In my experience this means you make a starter. If you dont want to invest the time and effort in making a starter then there’s really no point to perfecting your yeast washing skills.

The quality of the fermentation would need to be tested or at least is subjective.

Agree..that would be interesting. I’m just assessing my results based on lag times of 12-18 hours, consistently hitting project FG, clean ferments, never having a “dumper”, and beer that my friends generally enjoy.

I am 50/50 on this compared to just buying a fresh pitch. If you are only brewing this beer once every three months and also making a starter anyway, the cost savings are not that large. It is yields more yeast or better flavor, maybe, but I would expect debate on this.

Precisely the point I’m trying to make to folks as they consider yeast washing...please think about the steps at the other end and make sure it’s really worth it to you.

Cheers!

 

[Moose_MI]

A better method of storage, IMO, is to selectively harvest yeast via a conical or by selecting the top portion of the yeast cake to avoid trub. When possible, top crop ale yeasts. Store this yeast either directly under the beer it fermented for use within a week, or use a dilute solution of sterlized water and the same beer for more than a week. Anything stored longer than a month gets tossed out or a portion thereof is used in a yeast starter to grow it back up.

Awesome! I think this is almost exactly what I do except instead of top cropping I’m rinsing yeast at the end of fermentation and storing in a diluted solution of boiled water and the beer that was fermented. Woo hoo! Thank you for sharing this...it’s nice to have a little validation of a process that I just sort of developed over time because it worked for me!

 

[Bassman2003]

Ok, now the $64,000 question to the community: With the dllute solution added and knowing one will make a starter on the other end, HOW LONG can one reliably store this yeast and expect a great fermentation in the next batch?

2 months?
3 months?
6 months?

 

[Moose_MI]

I have about 1.5 cups of rinsed lager yeast that’s almost a year old. It was from my first shot at using lager yeast last year and it was good. I think it was S-23. I probably need to either dump it or see of it’s still got some life. I’ll put a starter together today and see what she does.

I will first take a whiff of it to see if it smells bad...then I’ll use a stir plate for 12-18 hrs...then let it ride for a few days and see if it can be resurrected.

We can discuss next steps once we see how this goes

 

[Bassman2003]

Thanks for sharing and rousting the old yeast. Looking forward to the discussion. When you asked about how long of a time period, I would benefit from 2-6 months of storage time as I like to brew different styles with different yeasts.

 

[Moose_MI]

And they’re off! Did not smell anything scary..in fact had very little smell at all. The diluted beer on top of yeast had oxidized pretty badly but that’s no surprise. I did a 3L 1.025 starter...a little smaller and lower OG than my normal 4L 1.035 starter but have read a little lower OG starter is suggested when trying to revive old yeast.

 

[Moose_MI]

We have life! I turned stir plate off after about 9 hrs. At about 13hrs the yeast was settling out and the top 1/3 of the starter was clear and things looked totally dormant. I got up this morning and at the 19hr mark it’s all cloudy again and starting to get a little krausen on top. Smells yeasty but other wise OK....woo hoo!

 

[Moose_MI]

Also, I checked some notes...This is Fermentis Saflager W-34/70. Purchased in April and brewed June 15. That means this yeast was stored for 9 months. I’m impressed at how quickly it seems to be taking off. Ive never done a starter w/ lager yeast but this is not much different than I see w/ 4-8 week old ale yeasts.

 

[Bassman2003]

Thanks for the followups. Interesting and positive behavior. How do we take this information and verify the yeast is valid, has good viability and is healthy? Are you planning on brewing with it soon? At the homebrew level, judging a beer made with it is kind of the only true gauge.

Some negatives mentioned in this thread are probability of a high number of dead cells and over-stressed cells on revive that would lead to off flavors during fermentation.

 

[Moose_MI]

I am soooo glad you asked! I guess the first question we should discuss is what are we trying to prove? So far I know that the “rinsing” process and storing under a diluted solution of the beer results in yeast with some level of health at 9months.
If I were doing this for me alone as part of my normal OCD tendencies i think I would let this starter ferment out for another day or 2, then I would swirl to get everything back into suspension, allow an hour or so to pass, and poor off the creamy part and discard whatI would assert are the dead and/or unhealthy cells which I would tell myself had settled to the bottom.

Then, I’d let that sit in fridge for a few days to condense my fresh healthy yeast. Then I’d do another starter but this would be the 4.5L 1.035 starter I normally do. As this is lager, I would then declare Ive got enough good yeast to properly ferment 10G of lager...if this were Ale yeast I would declare it was enough for 15G and I would plan my brew day.

Many rational people would say Ive already passed the point of value in saving this yeast vs buying fresh. I understand that. Excluding time from the math, I’d say I would still be a little ahead in terms of $$ invested. For 10G of lager you’d need 4 packs of yeast. I think I’ve got less DME $ invested then what 4 packs of yeast would cost.

So....what do you think? Should I go this route or would you suggest something more useful to explore as part of this?

 

[Bassman2003]

I think this is a pretty good opportunity to learn some things. 9 months and lager yeast is a strong test. My knowledge of re-pitching is nill as I always have purchased new, but I am interested in longer storage. Hopefully we can get some more folks involved.

Maybe make a new thread in this forum with a title like "I have 9 month old washed lager yeast, how to check its health & use?" Or something of the sort. A lot of folks would benefit from this and if it does result in a working situation, my habits would change.

I am unsure about separating new and old yeast in the same container. That seems like a tough one. A mini conical would be nice to have. Mason jar conical?

 

[Moose_MI]

I like the idea of new thread. Can you expand a bit on the mason jar conical? Separating the old and new yeast is what I thought I would be attempting (dare I say approximating?) by swirling the starter and then allowing an hr or so for things to settle and then poor off the top ~2L or so leaving ~1L or so behind.

Would you have any idea if this would be remotely effective? Maybe this where the broader audience would contribute?

 

[Moose_MI]

Here we are at the 24hr mark. Lots of activity now..lots of little CO2 bubbles going up the sides. Kraken on top is a little mess than impressive but I’m thinking that’s because it’s lager yeast (bottom fermenting).
I noticed 3 distinct layers at the bottom. I tried to get a close up so you could see it also. It sort of give me optimism about the swirl...settle..and door off approach may have merit

 

[Moose_MI]

New thread started...

https://www.homebrewtalk.com/forum/threads/reusing-9month-old-lager-yeast.676557/