How long can we save Ale yeast in the fridge.

[BrewingWisdom]

Hello
My batch is nearing to complete fermentation and I want to save my ale yeast slurry at the bottom of the fermenter.
I plan to save it in the fridge in some air tight glass container. For how long is it feasible to preserve the ale yeast this way?

 

[Miraculix]

One week, afterwards I'd do a starter.

 

[McMullan]

At relatively low cell density, e.g. in a bottle of beer, yeast can survive for more than 100 years. If your aim is to repitch without making a starter, I'd say several days for a predictable fermentation. If you plan to make a starter, just store a small, dilute fraction of the slurry. The higher the cell density the less time it remains viable.

 

[Steveruch]

Hello
My batch is nearing to complete fermentation and I want to save my ale yeast slurry at the bottom of the fermenter.
I plan to save it in the fridge in some air tight glass container. For how long is it feasible to preserve the ale yeast this way?

Be careful using an air tight glass container. Any yeast activity could cause a bottle bomb.

 

[BrewingWisdom]

Be careful using an air tight glass container. Any yeast activity could cause a bottle bomb.

Well then using a simple lid is better. Like using a empty jam bottle.

 

[NitrogenWidget]

i've kept unwashed notty in a jar for 6 months and it came back when i made a starter with it.
i don't think anything else survived that long though except kveik yeasts.

 

[BrewingWisdom]

i've kept unwashed notty in a jar for 6 months and it came back when i made a starter with it.
i don't think anything else survived that long though except kveik yeasts.

What is nottty ?

 

[NitrogenWidget]

What is nottty ?

Nottingham yeast.

 

[An Ankoù]

Hello
My batch is nearing to complete fermentation and I want to save my ale yeast slurry at the bottom of the fermenter.
I plan to save it in the fridge in some air tight glass container. For how long is it feasible to preserve the ale yeast this way?

Better than an airtight container would be an open glass container like a jam jar, or a small conical plask with a bit of aluminium foil over the top. You can keep it in place with a rubber band if you like.

 

[IslandLizard]

You can store yeast slurries for months, years even, in the fridge.* But viability goes down, as much as 5-20% per month, highly depending on packaging and storage conditions.
http://www.brewunited.com/yeast_calculator.php
When harvested from a batch, there will be about 4-5x the number of cells you pitched. For example if you pitched 100 billion cells you'll have 400-500 billion cells at the end of the fermentation. How many times she multiplies and how many survive depends on pitch rate, gravity, alcohol content, viability of the yeast you pitched, aeration/oxygenation, and so on.

When storing the slurry harvested from a batch, leave some of the beer on top, in the storage jar. If it's high(er) alcohol, say above 5-6%, dilute it with (sterile) water. Many of us use "canning" jars, they come in many sizes 4 oz - 16 oz (1 pint). Those are probably the most useful, depending on the space in your fridge. But any jam/jelly jars, whatever you have, work just as fine too. Save the lids too. Glass is easier to sterilize or sanitize than plastic and is air tight.

When saving yeast from a previous fermentation, after transferring the beer to a bottling bucket or keg, leave some beer behind on top of the trub/yeast cake on the bottom of your fermenter. About 1/4-1/2" is enough. When done with bottling/kegging, swirl or stir that cake up with the leftover beer into a homogeneous slurry. Making sure you're getting the sticky cake from the bottom suspended too. Dump the slurry into a 1/2 gallon jar, such as a pickle jar or a few smaller ones.

Needless to say, when handling yeast, work in a sanitary way, as much as possible.

* I just "revived" yeast I had bought in March 2015. The yeast was kept in a 34F fridge, inside a small box with other bottles/jars of yeast. Most had been used about half, the remaining half left in the original bottles. One jar was still unopened. They all started out with at least 400 billion cells at packaging. A week later, each yielded about 4 oz of nice creamy yeast slurry.

 

[BrewingWisdom]

They all started out with at least 400 billion cells at packaging

How do you count yeast cells ?

 

[BrewingWisdom]

You can store yeast slurries for months, years even, in the fridge.* But viability goes down, as much as 5-20% per month, highly depending on packaging and storage conditions.
http://www.brewunited.com/yeast_calculator.php
When harvested from a batch, there will be about 4-5x the number of cells you pitched. For example if you pitched 100 billion cells you'll have 400-500 billion cells at the end of the fermentation. How many times she multiplies and how many survive depends on pitch rate, gravity, alcohol content, viability of the yeast you pitched, aeration/oxygenation, and so on.

When storing the slurry harvested from a batch, leave some of the beer on top, in the storage jar. If it's high(er) alcohol, say above 5-6%, dilute it with (sterile) water. Many of us use "canning" jars, they come in many sizes 4 oz - 16 oz (1 pint). Those are probably the most useful, depending on the space in your fridge. But any jam/jelly jars, whatever you have, work just as fine too. Save the lids too. Glass is easier to sterilize or sanitize than plastic and is air tight.

When saving yeast from a previous fermentation, after transferring the beer to a bottling bucket or keg, leave some beer behind on top of the trub/yeast cake on the bottom of your fermenter. About 1/4-1/2" is enough. When done with bottling/kegging, swirl or stir that cake up with the leftover beer into a homogeneous slurry. Making sure you're getting the sticky cake from the bottom suspended too. Dump the slurry into a 1/2 gallon jar, such as a pickle jar or a few smaller ones.

Needless to say, when handling yeast, work in a sanitary way, as much as possible.

* I just "revived" yeast I had bought in March 2015. The yeast was kept in a 34F fridge, inside a small box with other bottles/jars of yeast. Most had been used about half, the remaining half left in the original bottles. One jar was still unopened. They all started out with at least 400 billion cells at packaging. A week later, each yielded about 4 oz of nice creamy yeast slurry.

Also do we need to bring that yeast slurry back to wort or whatever liquid we are fermenting temperature before pitching ?

 

[IslandLizard]

How do you count yeast cells ?

A decent microscope, a hemocytometer, some skill in accurately diluting a representative sample to a known fraction, a drop of methylene blue as an indicator to tint dead cells blue/dark, being systematic and exercise patience when counting. Then finish with some math to compute back the (live) cells in the actual batch. Easy peasy... after you've done a few.

A quick way of estimating cell count is by using a yeast pitch calculator (I linked to in #10) and comparing the volumes of the slurry before and after the starter or a fermented batch.*

* When harvesting yeast from a fermented batch, there's usually trub mixed in, so gross volume is not meaningful. After good mixing, you could re-pitch say 1/5 or 1/4 into a new batch.
If you want to repitch "cleaner" yeast from a previous batch, containing far less trub, the yeast can be rinsed first. This process is often, but erroneously, called "yeast washing." Yeast washing is actually a whole different process, involving an acid.

 

[bracconiere]

Well then using a simple lid is better. Like using a empty jam bottle.

i just store mine in tupperware or anything with a loose sealing lid...

How do you count yeast cells ?

back to the microscope again!

Also do we need to bring that yeast slurry back to wort or whatever liquid we are fermenting temperature before pitching ?

i always just pitch it at fridge temp....

 

[mashpaddled]

Like @IslandLizard I've successfully revived strains stuck in the back of the fridge for a long time. I have quite a few mason jars of yeast in there and I'm pretty bad about pulling them out and feeding them. Some only get fed like once a year. No problem with harvesting from the jars it just takes a little extra planning and time to build up to the volume you need for a batch.

 

[duncan_disorderly]

I'm drinking a nice bitter I made a few weeks ago with 1469 yeast that was recovered from slurry I harvested nearly 6 and a half years earlier. It was kept in a jar in my beer fridge. I just did a 1020 step and a 1040 step. I tried to resurrect two other slurries at the same time that were only 2 to 3 years old but they didn't smell good so I dumped them.

 

[BrewingWisdom]

i always just pitch it at fridge temp....

Well there is thing called thermal shock which happens when the temperature of the wort differs from the temperature of the yeast starter.

 

[Oleson M.D.]

How do you count yeast cells ?

One at a time.

 

[Alan Reginato]

Nahhh, I save slurry in beer bottles, just let the caps a little loose, to release internal pressure. For that, I cap the bottle and reopen with a knife then recap manually.

My oldest try was 5 months old slurry and got same lag time as a new dry yeast package, 12 hours. For a 25 l batche. Yeasts are tough!

 

[Miraculix]

Nahhh, I save slurry in beer bottles, just let the caps a little loose, to release internal pressure. For that, I cap the bottle and reopen with a knife then recap manually.

My oldest try was 5 months old slurry and got same lag time as a new dry yeast package, 12 hours. For a 25 l batche. Yeasts are tough!

Sure,I even had older yeast than that, that still worked well. But I also had a month old yeast that completely crapped out and ruined the beer.

Once you loose a few batches you start to want to have some reliability, that's where starters come into play.

 

[McMullan]

One at a time.

Very occasionally I count millions at once, just to test my empirical assumptions are on track.

And they are always on track. Conclusion: not much point in home brewers counting yeast. What works best for any given home brewer can be determined empirically, by brewing and observing.

 

[scrap iron]

I use quart glass canning jars. You just have to keep the lid loose a quarter turn so any activity doesn't warp the lid or break the glass. After a week or so if its ok I'll tighten the lid. As stated before be careful about sanitizing and keep yeast under beer. I have a Stong Bitter in the fermenter now with Imperial Pub originally from January that was a stepped up starter.
I use my oldest stored yeast first. I'll make a starter with a part of slurry and after about an hour I pour off the yeast in suspension into a new jug to leave most dead and poor health yeast behind. I have four different jars stored, some Ale and some Lager.

 

[twd000]

At relatively low cell density, e.g. in a bottle of beer, yeast can survive for more than 100 years. If your aim is to repitch without making a starter, I'd say several days for a predictable fermentation. If you plan to make a starter, just store a small, dilute fraction of the slurry. The higher the cell density the less time it remains viable.

Had not thought of the cell density effect until you mentioned it. I’ve had success culturing yeast from bottle conditioned commercial beers that were quite old

My quart jars of slurry are of course much higher cell density, so they degrade faster?

I keg my beers, but I wonder if it would be worth bottling a single serving from each batch, to serve as a sort of “yeast bank” in my beer fridge? And just build up a starter when I want to use that strain again

 

[BrewingWisdom]

One at a time.

Damn you have a long life noah.

 

[McMullan]

Had not thought of the cell density effect until you mentioned it. I’ve had success culturing yeast from bottle conditioned commercial beers that were quite old

My quart jars of slurry are of course much higher cell density, so they degrade faster?

I keg my beers, but I wonder if it would be worth bottling a single serving from each batch, to serve as a sort of “yeast bank” in my beer fridge? And just build up a starter when I want to use that strain again

At fridge temperature and with scarce nutrients the yeast cells are going to be resting in a dormant state. Metabolism just ticking over, but metabolic activity nonetheless. With higher cell densities what little resources remain get exhausted sooner. Then cell viability falls further and further. Literally a yeast famine. For longer term storage a small volume (mls) dilute slurry is going to last much longer. And take up less storage space.

 

[Wayne1]

 

[RWurster]

Im not sure if I missed it but how much slurry per liter of starter, a cup?

 

[McMullan]

That looks interesting. Hopefully, it's not just another prototype toy sold by a fancy online app. I"m not sure it's useful at home brew scales, tbh. Microscopy and cell viability measurements very much follow the 'crap in crap out' principle. If repitching fresh yeast or building up starters from initially small volumes, it's safe to assume >99% viability. For home brew fermentations, empirical observations are probably more reliable than second guessing samples measured are representative of what's being pitched.

 

[McMullan]

Im not sure if I missed it but how much slurry per liter of starter, a cup?

How long's a piece of string? What proportion of the slurry is yeast cells? Depends on the brewer. It's easier to keep good records then adjust accordingly in subsequent batches.

 

[Wayne1]

That looks interesting. Hopefully, it's not just another prototype toy sold by a fancy online app. I"m not sure it's useful at home brew scales, tbh. Microscopy and cell viability measurements very much follow the 'crap in crap out' principle. If repitching fresh yeast or building up starters from initially small volumes, it's safe to assume >99% viability. For home brew fermentations, empirical observations are probably more reliable than second guessing samples measured are representative of what's being pitched.

The company has been around since 2016. It was developed along with VLB in Germany. The product is now used in 40 countries.
Occulyze
It is mostly intended for small to medium pro brewers that do not have a full lab.
I saw it at the Craft Brewing Expo this year. I was impressed with it. The cost of $700 for equipment and $70 a year for software is not too much for most small breweries.