# Re-using Yeast Cake



## Murdoch (9/5/10)

G`day There,

I only do 46 L brews as I have 50 L kegs
& as I keg one brew I generally nearly alway put the next brew down at the same time
I would like to re-use the yeast cake for the next brew
Whats the best (or even different) ways of doing it ?
I have read Chillers method of yeast harvesting for future pitching but what would you do if you wanted to reuse the yeast cake straight away & how much would I need for the 46L batch ?
I have read comments like "I put the next brew straight on top of the previous yeast cake" ......
Surely its not that simple as to rack one brew & throw another on top of the previous yeast cake ? ....... or is it ?
Preferably I`d like to use the yeast cake (or some of it) to fire up the next brew & put some away for future batches if there was enough for both ?
I plan to experiment with the different dry yeasts then move to the liquid yeasts once I get a handle on it
I did do a search but didnt find what I was looking for

Thanks

Murdoch


----------



## seemax (9/5/10)

You can rack your next brew directly on top of the cake, but mostly likely you will be over pitching.

Use mrmalty's pitching rate calculator... i would guess you only need about a cup of thick slurry for 46L assuming its an ale, double or more for a lager.

I usually sanitise a spoon and scoop some cake out for storage in a bottle, then I leave about the right amount. 

It's best to brew the same type of beer or darker and I wouldn't do an low IBU lager on top of an IPA or stout!


----------



## Screwtop (9/5/10)

http://www.aussiehomebrewer.com/forum//ind...st&p=618018


----------



## Wolfy (9/5/10)

Murdoch said:


> Surely its not that simple as to rack one brew & throw another on top of the previous yeast cake ? ....... or is it ?
> Preferably I`d like to use the yeast cake (or some of it) to fire up the next brew & put some away for future batches if there was enough for both ?


Yes you could simply throw the next batch of wort directly ontop - if you wanted.
Personalty I prefer to harvest, then wash the yeast cake, I can then control the amount of yeast I pitch into the new batch and ensure that yeast is free of any foreign matter that I'd not want to pitch (break material or hop debris).
It's also very easy to store some yeast for later use as part of the washing process.


----------



## Nick JD (9/5/10)

I often swirl the fermenter up after I've filled the last bottle and fill a 600ml Coke PET with the mud that comes out the tap. 

Kept in the fridge, it settles to about an inch of solid yeasty stuff on the bottom. 

I bring it out of the fridge on brewing day and let it warm to somewhere around 12C - and pour the beer off the top into a glass and drink it.

Then I swirl up the yeast on the bottom and pour it into the new wort in the fermenter. It's off and running in about 5 hours - way quicker than packet yeast.

You would be fine to just fill a sanitized 600ml bottle with swirlings, cap it and when you're ready pour the whole bottle in. I like the idea of taking some slurry from the tap as scooping a cup in there seems like an infection route to me.


----------



## Yob (10/5/10)

Nick JD said:


> I bring it out of the fridge on brewing day and let it warm to somewhere around 12C - and pour the beer off the top into a glass and drink it.
> 
> Then I swirl up the yeast on the bottom and pour it into the new wort in the fermenter. It's off and running in about 5 hours - way quicker than packet yeast.



What would your wort temps be in this case? Would the yeast not suffer temp shock if the wort was too warm? edit: assuming lagers here?


----------



## QldKev (10/5/10)

Murdoch said:


> G`day There,
> 
> I only do 46 L brews as I have 50 L kegs
> & as I keg one brew I generally nearly alway put the next brew down at the same time
> ...




I often reuse the yeast cake; for up to many months. (depending on what I am brewing)

Drain beer
Swirl left overs
Leave approx 1 good cup (double this for your volume)
drop new beer ontop


----------



## argon (10/5/10)

I scoop up about 300ml worth of yeast cake into 3 separate microwave sterilised containers. Seal, label and then keep in the fridge. 

When next brew comes along where I want to use that strain, I make a starter as per usual. Poor off the little bit of beer on top and taste looking for infections. If it's all good, I then pitch the whole contents of container into the starter wort. 24 hours later, high krausen and pitch next NC cube on top. Pretty simple.


----------



## Nick JD (10/5/10)

iamozziyob said:


> What would your wort temps be in this case? Would the yeast not suffer temp shock if the wort was too warm? edit: assuming lagers here?



12C yeast is perfect for a lager. Let it warm up more for ales if you want - I don't.

In my experience people worry too much about yeast getting shocked by temperature changes. 

How many of you take a packet of dried yeast out of the fridge/freezer and rehydrate it in 25C water? 

I've dumped the whole 600ml PET from the 4C fridge into a 20C ale wort before and it's taken off quick smart. Yeast is pretty hardy. If anything you're selecting the best of the bunch by killing the weakling cells off at pitching.


----------



## Steve (10/5/10)

Nick JD said:


> 12C yeast is perfect for a lager. Let it warm up more for ales if you want - I don't.
> 
> In my experience people worry too much about yeast getting shocked by temperature changes.
> 
> ...




cold yeast to warm wort = fine
warm yeast to cold wort = not very happy


----------



## Murdoch (12/5/10)

Many thanks for the replies & advice
What I`m thinking I`ll do is to catch the yeast bed after the fermenter has been decanted into the keg
Place yeast sludge in bottle/s in the fridge
Using a freshly cleaned fermenter (or the previous one cleaned up) make up the next brew
Bring the temp down to 21-22 ? 
I`ll then use some of the stored yeast bed to reactivate the new brew, Wait to see some fermenting activity then drop to 17-18 ?
& the remaining yeast bed I`ll wash & store as per Chillers method

I have a question about quantities to use .....

The Mr Malty calculator suggests around 200 ml (depending on harvest date)
Now is this "200" ml washed yeast cake solution or the straight sludge out of the fermenter ?
Qld Kev suggests I need about 2 cups of fresh yeast cake for my 46L batch
If I was to make a starter from some of the stored washed yeast cake how much would I need for the 46L batch ?

Thanks again for all the advice
Its great to have a live resource like this forum & its members


----------



## Wolfy (12/5/10)

Murdoch said:


> The Mr Malty calculator suggests around 200 ml (depending on harvest date)
> Now is this "200" ml washed yeast cake solution or the straight sludge out of the fermenter ?
> Qld Kev suggests I need about 2 cups of fresh yeast cake for my 46L batch
> If I was to make a starter from some of the stored washed yeast cake how much would I need for the 46L batch ?


The 'reuse slurry' part of the calculator has a slider for the percentage of yeast, if you were to reuse sludge directly, slide it to indicate more non-yeast solids, if its washed slurry, slide it the other way to say its just yeast.
So I'd take the 200ml as clean/washed slurry in your case.

The 'create starter' part of the calculator would tell you how large a starter you need, however I think you'll find it's quite large, which is why re-using the yeast cake is an ideal option for larger or higher gravity fermentation.


----------



## Murdoch (23/5/10)

I played around with Mr Malty settings & it seemed at worst case scenario the 46L batch would need 500ml of slurry
Yesterday I kegged the Pale Ale after it had been CC @ 4 C for 3 days
After kegging I drained off most of the small amount of beer on the cake, swirled it all around then filled 3 x 500 ml sterilised jars
I made up a 46L batch of Real Ale adding some cold pre-boiled water & the temp finished up at 21 C
I let one of the jars of slurry slightly warm up for a short while then shook up & added to the fermenter
It seemed to work really well
Within an hour there was some bubbling & krausen
I gradually dropped the temp to 17 over a few hours & by last night it was rocketing away
This morning its bubbling like mad & a thick band of krausen
The yeast out of the packet was much slower to take off & I didn't see it as active as this is now
I`ll wash & store the other 2 samples of yeast & I`ll probably practice making starters just to get a feel of it
I`ve heard washed yeast stored correctly will last many months ?
How many times could I expect to be able to directly reuse the yeast cake as I did yesterday ?
I`ve heard anything from only 3 times to dozens of times ?

Thanks for the feedback & advice


----------

