Yeast Thread 2021

[Shamus O'Sean]

26 minutes ago, Pale Man said:

Question from a yeast dummy. How do you overbuild a yeast starter?

Here is a great thread about doing a yeast starter, including an overbuild.

It is basically the same as any other starter, except you need to calculate how much yeast you need for the batch and the overbuild.  Then you can size the starter accordingly.  The first part of my post discusses calculating the size of the starter to make enough yeast cells for your overbuild and the batch you are about to do. 

Harvest the overbuild is the only extra steps.  But that is pretty easy.  See the latter section of my post for more details about harvesting and storing the overbuild and retaining the yeast for brew day.

[Classic Brewing Co]

1 hour ago, Pale Man said:

Question from a yeast dummy. How do you overbuild a yeast starter?

Beats me. 

[iBooz2]

2 hours ago, Pale Man said:

Question from a yeast dummy. How do you overbuild a yeast starter?

An Overbuild Starter, a practical example

Continuing on from our W-34/70 yeast mentioned above, we are now going to brew a lager of batch size 22 L and an OG of 1.045 and we want to build an over-build starter using just one sachet to give us enough fresh yeast to go into cold storage for out next starter and enough to ferment our lager out.

Fermentis specs sheet for W-34/70 tells us that there is greater than 6 billion cells per gram (as with most of their range of yeast produced) and as their sachet size is 11.5 g that gives us our starting point of 69 billion cells.

Next, we need to know the pitching rate and for lagers this is at 1.5 minimum and at 2.0 for higher gravity lagers.  As our lager’s OG is only 1.045, we settle on a rate of 1.5.

Plugging the known numbers into a starter calculator like Brewers Friend we see that the target pitch rate of cells required is 369 billion cells, so we are 300 billion cells short and that is only what is required to go into your 22 L FV.  We also want to achieve that number and have an excess number of cells to go into cold storage for our next starter.  Therefore, we need the 369 billion plus another 69 billion so total 438 billion (at least).

So, we make a 3 L starter, boiled for a few minutes using 271 g of DME which gives it a SG of 1.034.  Once the starter wort has cooled overnight (covered), put it on the stir-plate at say 14-15 C (remember this is a lager yeast and we don't want to kill them) and spin it up for 12 hrs or so then switch off the stir-plate.  After the starter has completely fermented out you end up with 449 billion cells suspended in the starter beer.

Once the ferment of that starter is finished completely (over few days) swirl up the yeast to get it all back up into full suspension or fire up the stir-plate again for about half an hour to do this job for you.  You then need to immediately decant at least 69 billion cells into a sanitised storage jar.  Reagent jars are perfect for this as they have volume markings printed on them.  I use 1 L and 500 ml sizes. 

How do we do this and get the numbers right, you might ask.

We need at least 69 billion cells to go into our storage jar and because we now have 449 billion suspended in the 3 L this works out to approximately 15% and 15% of 3 L is 0.48 L.   So, a 500 ml reagent jar would be perfect size for storage, fill it and the remainder of the starter will go into your FV once you have cold crashed that part of the starter to separate the fresh yeast from the un-hopped wort.

Label and date your storage jar and keep it in the fridge.  Once the remains of the starter beer has been cold crashed for a day or so to drop the yeast out, you can then tip off the un-hopped beer (from the remaining starter that is) just leaving enough to swirl the yeast up so you can tip it into your FV.  You will do the same cold crash routine with your storage jar when you are ready to tip that yeast into your next starter.

Don’t forget that there is a stir bar in there and I have nearly lost a few of them down the sink, luckily, I have a SS sink and they stuck to the sink itself, but I have forgotten and dumped the stir bar into the FV along with the yeast a couple of times.  Now I use a strong small, rare-earth magnet taped the outside of the flask to hold the stir bar insitu whilst I pour the yeast into the FV

This is a lager example; ales have a different pitching rate say 0.75 for a 1.045 SG wort.

Hope that helps everyone.

Edited March 3 by iBooz2

[Pale Man]

11 minutes ago, iBooz2 said:

An Overbuild Starter, a practical example

Continuing on from our W-34/70 yeast mentioned above, we are now going to brew a lager of batch size 22 L and an OG of 1.045 and we want to build an over-build starter using just one sachet to give us enough fresh yeast to go into cold storage for out next starter and enough to ferment our lager out.

Fermentis specs sheet for W-34/70 tells us that there is greater than 6 billion cells per gram (as with most of their range of yeast produced) and as their sachet size is 11.5 g that gives us our starting point of 69 billion cells.

Next, we need to know the pitching rate and for lagers this is at 1.5 minimum and at 2.0 for higher gravity lagers.  As our lager’s OG is only 1.045, we settle on a rate of 1.5.

Plugging the known numbers into a starter calculator like Brewers Friend we see that the target pitch rate of cells required is 369 billion cells, so we are 300 billion cells short and that is only what is required to go into your 22 L FV.  We also want to achieve that number and have an excess number of cells to go into cold storage for our next starter.  Therefore, we need the 369 billion plus another 69 billion so total 438 billion (at least).

So, we make a 3 L starter, boiled for a few minutes using 271 g of DME which gives it a SG of 1.034.  Once the starter wort has cooled overnight (covered), put it on the stir-plate at say 14-15 C (remember this is a lager yeast and we don't want to kill them) and spin it up for 12 hrs or so then switch off the stir-plate.  After the starter has completely fermented out you end up with 449 billion cells suspended in the starter beer.

Once the ferment of that starter is finished completely (over few days) swirl up the yeast to get it all back up into full suspension or fire up the stir-plate again for about half an hour to do this job for you.  You then need to immediately decant at least 69 billion cells into a sanitised storage jar.  Reagent jars are perfect for this as they have volume markings printed on them.  I use 1 L and 500 ml sizes. 

How do we do this and get the numbers right, you might ask.

We need at least 69 billion cells to go into our storage jar and because we now have 449 billion suspended in the 3 L this works out to approximately 15% and 15% of 3 L is 0.48 L.  A 500 ml reagent jar would be perfect size for storage, fill it and the remainder of the starter will go into your FV once you have cold crashed that part of the starter to separate the fresh yeast from the un-hopped wort.

Label and date your storage jar and keep it in the fridge.  Once the remains of the starter beer has been cold crashed for a day or so to drop the yeast out, you can then tip off the un-hopped beer (from the remaining starter that is) just leaving enough to swirl the yeast up so you can tip it into your FV.

Don’t forget that there is a stir bar in there and I have nearly lost a few of them down the sink, luckily, I have a SS sink and they stuck to the sink itself, but I have forgotten and dumped the stir bar into the FV along with the yeast a couple of times.  Now I use a strong small, rare-earth magnet taped the outside of the flask to hold the stir bar insitu whilst I pour the yeast into the FV

This is a lager example; ales have a different pitching rate say 0.75 for a 1.045 SG wort.

Hope that helps everyone.

 

[Pale Man]

44 minutes ago, iBooz2 said:

An Overbuild Starter, a practical example

Continuing on from our W-34/70 yeast mentioned above, we are now going to brew a lager of batch size 22 L and an OG of 1.045 and we want to build an over-build starter using just one sachet to give us enough fresh yeast to go into cold storage for out next starter and enough to ferment our lager out.

Fermentis specs sheet for W-34/70 tells us that there is greater than 6 billion cells per gram (as with most of their range of yeast produced) and as their sachet size is 11.5 g that gives us our starting point of 69 billion cells.

Next, we need to know the pitching rate and for lagers this is at 1.5 minimum and at 2.0 for higher gravity lagers.  As our lager’s OG is only 1.045, we settle on a rate of 1.5.

Plugging the known numbers into a starter calculator like Brewers Friend we see that the target pitch rate of cells required is 369 billion cells, so we are 300 billion cells short and that is only what is required to go into your 22 L FV.  We also want to achieve that number and have an excess number of cells to go into cold storage for our next starter.  Therefore, we need the 369 billion plus another 69 billion so total 438 billion (at least).

So, we make a 3 L starter, boiled for a few minutes using 271 g of DME which gives it a SG of 1.034.  Once the starter wort has cooled overnight (covered), put it on the stir-plate at say 14-15 C (remember this is a lager yeast and we don't want to kill them) and spin it up for 12 hrs or so then switch off the stir-plate.  After the starter has completely fermented out you end up with 449 billion cells suspended in the starter beer.

Once the ferment of that starter is finished completely (over few days) swirl up the yeast to get it all back up into full suspension or fire up the stir-plate again for about half an hour to do this job for you.  You then need to immediately decant at least 69 billion cells into a sanitised storage jar.  Reagent jars are perfect for this as they have volume markings printed on them.  I use 1 L and 500 ml sizes. 

How do we do this and get the numbers right, you might ask.

We need at least 69 billion cells to go into our storage jar and because we now have 449 billion suspended in the 3 L this works out to approximately 15% and 15% of 3 L is 0.48 L.   So, a 500 ml reagent jar would be perfect size for storage, fill it and the remainder of the starter will go into your FV once you have cold crashed that part of the starter to separate the fresh yeast from the un-hopped wort.

Label and date your storage jar and keep it in the fridge.  Once the remains of the starter beer has been cold crashed for a day or so to drop the yeast out, you can then tip off the un-hopped beer (from the remaining starter that is) just leaving enough to swirl the yeast up so you can tip it into your FV.  You will do the same cold crash routine with your storage jar when you are ready to tip that yeast into your next starter.

Don’t forget that there is a stir bar in there and I have nearly lost a few of them down the sink, luckily, I have a SS sink and they stuck to the sink itself, but I have forgotten and dumped the stir bar into the FV along with the yeast a couple of times.  Now I use a strong small, rare-earth magnet taped the outside of the flask to hold the stir bar insitu whilst I pour the yeast into the FV

This is a lager example; ales have a different pitching rate say 0.75 for a 1.045 SG wort.

Hope that helps everyone.

Excellent advice. I'm reading and re reading for it to compute fella.

I'm very interested just seems out of my depth at the moment.

[Aussiekraut]

16 hours ago, iBooz2 said:

An Overbuild Starter, a practical example

Continuing on from our W-34/70 yeast mentioned above, we are now going to brew a lager of batch size 22 L and an OG of 1.045 and we want to build an over-build starter using just one sachet to give us enough fresh yeast to go into cold storage for out next starter and enough to ferment our lager out.

Fermentis specs sheet for W-34/70 tells us that there is greater than 6 billion cells per gram (as with most of their range of yeast produced) and as their sachet size is 11.5 g that gives us our starting point of 69 billion cells.

Next, we need to know the pitching rate and for lagers this is at 1.5 minimum and at 2.0 for higher gravity lagers.  As our lager’s OG is only 1.045, we settle on a rate of 1.5.

Plugging the known numbers into a starter calculator like Brewers Friend we see that the target pitch rate of cells required is 369 billion cells, so we are 300 billion cells short and that is only what is required to go into your 22 L FV.  We also want to achieve that number and have an excess number of cells to go into cold storage for our next starter.  Therefore, we need the 369 billion plus another 69 billion so total 438 billion (at least).

So, we make a 3 L starter, boiled for a few minutes using 271 g of DME which gives it a SG of 1.034.  Once the starter wort has cooled overnight (covered), put it on the stir-plate at say 14-15 C (remember this is a lager yeast and we don't want to kill them) and spin it up for 12 hrs or so then switch off the stir-plate.  After the starter has completely fermented out you end up with 449 billion cells suspended in the starter beer.

Once the ferment of that starter is finished completely (over few days) swirl up the yeast to get it all back up into full suspension or fire up the stir-plate again for about half an hour to do this job for you.  You then need to immediately decant at least 69 billion cells into a sanitised storage jar.  Reagent jars are perfect for this as they have volume markings printed on them.  I use 1 L and 500 ml sizes. 

How do we do this and get the numbers right, you might ask.

We need at least 69 billion cells to go into our storage jar and because we now have 449 billion suspended in the 3 L this works out to approximately 15% and 15% of 3 L is 0.48 L.   So, a 500 ml reagent jar would be perfect size for storage, fill it and the remainder of the starter will go into your FV once you have cold crashed that part of the starter to separate the fresh yeast from the un-hopped wort.

Label and date your storage jar and keep it in the fridge.  Once the remains of the starter beer has been cold crashed for a day or so to drop the yeast out, you can then tip off the un-hopped beer (from the remaining starter that is) just leaving enough to swirl the yeast up so you can tip it into your FV.  You will do the same cold crash routine with your storage jar when you are ready to tip that yeast into your next starter.

Don’t forget that there is a stir bar in there and I have nearly lost a few of them down the sink, luckily, I have a SS sink and they stuck to the sink itself, but I have forgotten and dumped the stir bar into the FV along with the yeast a couple of times.  Now I use a strong small, rare-earth magnet taped the outside of the flask to hold the stir bar insitu whilst I pour the yeast into the FV

This is a lager example; ales have a different pitching rate say 0.75 for a 1.045 SG wort.

Hope that helps everyone.

Just a quick one, does the stir plate have to run the entirety of the starter fermenting? 

I'm just trying to work out some logistics here. Not an easy task with my shonky planning   I take it, I can leave a finished starter at CC temps for a week or so without affecting it. I'll just have to let it come up in temp before pitching. Does that sound about right?

[iBooz2]

3 hours ago, Aussiekraut said:

Just a quick one, does the stir plate have to run the entirety of the starter fermenting? 

I'm just trying to work out some logistics here. Not an easy task with my shonky planning   I take it, I can leave a finished starter at CC temps for a week or so without affecting it. I'll just have to let it come up in temp before pitching. Does that sound about right?

@Aussiekraut   No just spin it for about the first 12 hrs or so then turn the stir plate off.    Yes, you can leave the finished starter at CC for a week or more without problems.  The longer (up to a point) the more yeast cells will drop out of the un-hopped beer.   And yes, I leave my jar or flask of starter yeast out on the bench while I sanitise the FV etc. but that is not necessary.   Dump some wort from the cube into the FV then the starter yeast then the rest of the cube as this technique helps to aerate the wort.   You could put the yeast into the FV first but that depends on how much sanitiser foam is still in there, you don't want to kill off some of your hard work straight off the bat.

Edited March 4 by iBooz2

[Aussiekraut]

2 minutes ago, iBooz2 said:

@Aussiekraut   No just spin it for about the first 12 hrs or so then turn stir plate off.    Yes, you can leave the finished starter at CC for a week or more without problems.  The longer (up to a point) the more yeast cells will drop out of the un-hopped beer.   And yes, I leave my jar of yeast out on the bench while I sanitise the FV etc. but that is not necessary.   Dump some wort from the cube into the FV then the starter yeast then the rest of the cube as this technique helps to aerate the wort.   You could put the yeast into the FV first but that depends on how much sanitiser foam is still in there, you don't want to kill off some of your hard work.

Thanks mate. I already follow the practice of putting some wort into the FV first and then pitching the yeast as I don't want to jeopardise things. I think with dry yeast, there isn't much danger but caution is the mother of the porcelain cabinet as they say. 

[Pale Man]

@iBooz2  @Shamus O'Sean how many days after starting a Coopers Bottled Yeast build should you see activity? As a rough guide.

Put my starter together Sunday, today being Tuesday no activity whatsoever. It looks like dead flat clear beer. I spun for the first 12 hours. Then turned off the plate.

 

[iBooz2]

16 minutes ago, Pale Man said:

@iBooz2  @Shamus O'Sean how many days after starting a Coopers Bottled Yeast build should you see activity? As a rough guide.

Put my starter together Sunday, today being Tuesday no activity whatsoever. It looks like dead flat clear beer. I spun for the first 12 hours. Then turned off the plate.

 

@Pale Man it should be starting to show signs of fermentation about now and condensate appearing on the inside of the flask. 

I presumed you boiled the wort for a few minutes first.

What temperature was the wort when you pitched the dregs?

What temperature is the wort in the flask sitting at now?

[Pale Man]

54 minutes ago, iBooz2 said:

@Pale Man it should be starting to show signs of fermentation about now and condensate appearing on the inside of the flask. 

I presumed you boiled the wort for a few minutes first.

What temperature was the wort when you pitched the dregs?

What temperature is the wort in the flask sitting at now?

@iBooz2   I boiled around 60 grams of light dried malt in 600 mls of water.

Cooled down to around 18C and threw in the dregs of 7 stubs. Sitting at 18C and looking as flat as Donald Trumps lips. Surely she should fire up soon?

[iBooz2]

12 minutes ago, Pale Man said:

@iBooz2   I boiled around 60 grams of light dried malt in 600 mls of water.

Cooled down to around 18C and threw in the dregs of 7 stubs. Sitting at 18C and looking as flat as Donald Trumps lips. Surely she should fire up soon?

That is a starter gravity of 1.037 but then you diluted it with too much beer with the dregs if I remember your other threads posts.  BTW where did that tread go?  You hide it or delete it?  I was going to look at pics that you put up there to get a rough calculation of the starter SG but that thread is gone.

It may already be done if you have diluted it too much.  Only way to know is take a gravity sample but don't do that just yet.  Bump up the temp to 22 instead and see if that makes some condensation.

[iBooz2]

@Pale Man and another thought.  Where those stubbies stored upright in your fridge for at least 7 days to settle most of the yeast down the bottom i.e. like a cold crash after bringing them home from the store.  Two weeks settling of yeast is even better.

[Shamus O'Sean]

2 hours ago, Pale Man said:

@iBooz2  @Shamus O'Sean how many days after starting a Coopers Bottled Yeast build should you see activity? As a rough guide.

Put my starter together Sunday, today being Tuesday no activity whatsoever. It looks like dead flat clear beer. I spun for the first 12 hours. Then turned off the plate.

 

I reckon it would be done by now.  Sometimes I see the same scenario with my starters.  As you said previously, the Coopers commercial yeast does not have a big Krausen.  It could have come and gone in the first 12 hours. 

Is there a thin layer of clean and creamy looking yeast on the bottom of the flask?

I usually leave my starters for another 36 - 48 hours after I turn off the stir plate.  By then, the yeast has mostly settled out.  With an overbuild starter I then turn the stir bar on again and leave it spin while I sterilise a mason jar and lid in boiling water.  Once the mason jar has cooled down, I transfer the overbuild volume to the mason jar, label it and put it in the back of the fridge.  The volume left in the flask usually gets put somewhere to cold crash, waiting to be used on brew day.  The link to my process has more detail about my method.

On brew day, I decant off the excess liquid from the flask.  I leave enough of the liquid to swirl up the yeast and pitch it into the batch.  I generally do not let the yeast rise to pitching temperature.  It is probably pitched, from fridge temps, within 10 minutes of pulling it from the fridge.

[Pale Man]

21 hours ago, iBooz2 said:

That is a starter gravity of 1.037 but then you diluted it with too much beer with the dregs if I remember your other threads posts.  BTW where did that tread go?  You hide it or delete it?  I was going to look at pics that you put up there to get a rough calculation of the starter SG but that thread is gone.

It may already be done if you have diluted it too much.  Only way to know is take a gravity sample but don't do that just yet.  Bump up the temp to 22 instead and see if that makes some condensation.

Ive decided now to throw the yeast with a can of Coopers English Bitter to see if its viable, if not then no great loss.

If it works then I'll know I'm doing the right thing. And brew my Pale Ale a bit later.

[Pale Man]

19 hours ago, Shamus O'Sean said:

Is there a thin layer of clean and creamy looking yeast on the bottom of the flask?

 

There is fella.

[Shamus O'Sean]

5 hours ago, Pale Man said:

There is fella.

Ladies and gentlemen, we have a winner.

5 hours ago, Pale Man said:

Ive decided now to throw the yeast with a can of Coopers English Bitter to see if its viable, if not then no great loss.

If it works then I'll know I'm doing the right thing. And brew my Pale Ale a bit later.

Harvest the yeast and store for your Pale Ale.  Or pour your Pale Ale straight onto the yeast cake.  

Quite interested to hear how the Coopers yeast goes with the English Bitter kit too.

[Tone boy]

Hi all,

First post in a while, I’ve been unable to brew while moving house, and some travel. Back into it now with my first brew using Kveik.

My question revolves around bottle carbonation with Kveik, and probably best to tag in the Sandman @BlackSands here ‘cos I know he has a lot of knowledge in this area.

I fermented the beer at 35 degrees C. After bottling to I have to raise the temperature back up to 30 degrees or thereabouts to kick start bottle fermentation? Or does room temp at 22 degrees work? And how long does bottle fermentation take with Kveik? I assume it is quick just like the initial fermentation.

Hope you are all well and happy.

cheers, Tone

 

[Triple B Brewing]

14 hours ago, Tone boy said:

Hi all,

First post in a while, I’ve been unable to brew while moving house, and some travel. Back into it now with my first brew using Kveik.

My question revolves around bottle carbonation with Kveik, and probably best to tag in the Sandman @BlackSands here ‘cos I know he has a lot of knowledge in this area.

I fermented the beer at 35 degrees C. After bottling to I have to raise the temperature back up to 30 degrees or thereabouts to kick start bottle fermentation? Or does room temp at 22 degrees work? And how long does bottle fermentation take with Kveik? I assume it is quick just like the initial fermentation.

Hope you are all well and happy.

cheers, Tone

 

Hi Tone, good ta have ya back cobber. 

Now I am by no means, and far from, being any type of expert on yeast, but you got my attention when you were suggesting getting your bottled brew back up to 30 degrees for second fermentation purposes - that seemed to me to be asking for trouble, so I went hunting and found this on the net which you might find helpful (interesting the piece on harvesting Kveik yeast).

Cheers !

 

[Tone boy]

Thanks BB. 
 

A good article and thanks for sharing. A little bit of info on bottling in there too!

As it was fermented at 35 degrees, I’m not sure 30 degrees for bottle conditioning is necessarily asking for trouble. There are many different strains of Kveik (I used Voss) and each one will behave slightly differently of course.
I was really just interested if I could store them in the brew cupboard at 22 degrees and carbonation would still occur…

As it turns out, I have now bottled the beer and am undertaking an exbeeriment:

16 bottles stored at 30 degrees C

2 bottles stored at 22 degrees C 

10 bottles stored at 22 degrees C with a small amount of rehydrated Coopers yeast added to each bottle.

I tried one of the ones stored at 30 degrees last night. There was definitely carbonation. Was quite nice, although more time in the bottle will be beneficial obviously as it was still very young.

Cheers TB

 

[Triple B Brewing]

1 hour ago, Tone boy said:

Thanks BB. 
 

A good article and thanks for sharing. A little bit of info on bottling in there too!

As it was fermented at 35 degrees, I’m not sure 30 degrees for bottle conditioning is necessarily asking for trouble. There are many different strains of Kveik (I used Voss) and each one will behave slightly differently of course.
I was really just interested if I could store them in the brew cupboard at 22 degrees and carbonation would still occur…

As it turns out, I have now bottled the beer and am undertaking an exbeeriment:

16 bottles stored at 30 degrees C

2 bottles stored at 22 degrees C 

10 bottles stored at 22 degrees C with a small amount of rehydrated Coopers yeast added to each bottle.

I tried one of the ones stored at 30 degrees last night. There was definitely carbonation. Was quite nice, although more time in the bottle will be beneficial obviously as it was still very young.

Cheers TB

 

Brilliant 

[Shamus O'Sean]

8 hours ago, Tone boy said:

Thanks BB. 
 

A good article and thanks for sharing. A little bit of info on bottling in there too!

As it was fermented at 35 degrees, I’m not sure 30 degrees for bottle conditioning is necessarily asking for trouble. There are many different strains of Kveik (I used Voss) and each one will behave slightly differently of course.
I was really just interested if I could store them in the brew cupboard at 22 degrees and carbonation would still occur…

As it turns out, I have now bottled the beer and am undertaking an exbeeriment:

16 bottles stored at 30 degrees C

2 bottles stored at 22 degrees C 

10 bottles stored at 22 degrees C with a small amount of rehydrated Coopers yeast added to each bottle.

I tried one of the ones stored at 30 degrees last night. There was definitely carbonation. Was quite nice, although more time in the bottle will be beneficial obviously as it was still very young.

Cheers TB

 

I understand Voss can ferment around 20°C.  It is supposed to behave like a pseudo-lager yeast at that temperature.  It may take a little longer to carbonate the bottles than the usual 2 weeks.

[iBooz2]

Thought I would copy this post from another thread to this one as this thread is more relevant.

 

Edited March 13 by iBooz2

[Back Brewing]

I kegged my galaxy Pale Ale today and was going to jar some yeast slurry but read conflicting reports how long I could keep it in the fridge some said 2 days some said up to a month

Anyone here have some thoughts on the subject?

[iBooz2]

8 hours ago, Back Brewing said:

I kegged my galaxy Pale Ale today and was going to jar some yeast slurry but read conflicting reports how long I could keep it in the fridge some said 2 days some said up to a month

Anyone here have some thoughts on the subject?

@Back Brewing, I have kept slurry for months and it's been OK.  What yeast was it?

It depends on the % ABV of the beer that it brewed when you harvested the slurry, remember alcohol is toxic to yeast so if it's going to sit under a layer of beer in your jar, (which is normal) that is generally the problem.  Low ABV then the yeast harvested will last longer, and of course a high alcohol beer will kill off the yeast more quickly.

Also, if you can make starter then you could use some of the slurry many months down the track to generate a fresh batch of yeasties.

In an ideal environment like a liquid yeast pouch they have a use by date six months into the future.

Edited March 13 by iBooz2