Re-using The Entire Yeast Cake

[Goose]

For the first time I thought I'd re-use the yeastcake for a lager brew, but instead of sampling the yeastcake and then repitching, I just pumped my next freshly prepared wort straight into the outlet of the fermenter following the racking of the previous brew.

This of course saves cleaning and sanitising the fermenter, reduces the risk of contamination/infection on sampling and repitching the yeast, as well as ensuring that you have an adequate quantity of yeast to start the brew off at lager fermentation temperatures ie 10 degrees C. As you'd expect the brew took off very fast and a taste test 5 days into the brew so far reveals no discernable off flavours. So far so good.

My question is, if I continue this process I have read some people do 3-4 times, would i expect the yeast cake volume to grow each time to the point where it simply becomes ridiculous.... ?

I guess this is a question of growth vs metabolism and I'd feel a tad uneasy about having 3 x the yeast I really need to complete a brew. Autolysis and off flavours spring to mind.

Comments please.

 

[bignath]

For the first time I thought I'd re-use the yeastcake for a lager brew, but instead of sampling the yeastcake and then repitching, I just pumped my next freshly prepared wort straight into the outlet of the fermenter following the racking of the previous brew.

This of course saves cleaning and sanitising the fermenter, reduces the risk of contamination/infection on sampling and repitching the yeast, as well as ensuring that you have an adequate quantity of yeast to start the brew off at lager fermentation temperatures ie 10 degrees C. As you'd expect the brew took off very fast and a taste test 5 days into the brew so far reveals no discernable off flavours. So far so good.

My question is, if I continue this process I have read some people do 3-4 times, would i expect the yeast cake volume to grow each time to the point where it simply becomes ridiculous.... ?

I guess this is a question of growth vs metabolism and I'd feel a tad uneasy about having 3 x the yeast I really need to complete a brew. Autolysis and off flavours spring to mind.

Comments please.

mmmmm, i'd be keen to know this aswell.

Would love to reuse a yeast cake, but i know not a whole lot about it.

 

[QldKev]

Yeast cake use on 2 lines :lol:

Go to Mr Malty click on the calculators and go to "repitching from slurry"
Work out how much yeast is needed, tip out what is not needed. Note that # (87ml) is for good yeast


OK, a couple more lines.

My procedure is not the perfect yeast world, but works great for me.
Based on normal 23L batch, around 1.045 gravity

Ensure no infections... should have done this anyway before bottling or kegging it.
Leave a bit more beer thickness than the yeast cake thickness in the fermenter.
Swirl fermenter to mix the lot up.

Tip out excess yeast into 330ml coke bottles, store them in the fridge.
Leave about 330ml in the fermenter and dump new wort ontop.

When ready to use the 3330ml bottles you saved, taste the beer from the top,
If ok dump into fermenter and dump wort ontop.


If you plan on keeping the yeast in the fridge >3 months, keep a 600ml bottle.


QldKev

 

[iralosavic]

I've done this many a time without any ill-effects. Reuse the entire yeast cake one time, that is. And yes the resulstant population of yeast (be it viable or otherwise) is certainly a lot larger after the second run.

I'm usually happy to get 50% extra value this way and then start again, but if you wanted you could use the yeast washing/rinsing method and/or rinse with phosphoric acid to remove all weak/dead yeast cells - although if you were happy to do that, you might as well have done it after the first generation... thinking out aloud now.

 

[mwd]

I do it very similar way to what Qldkev does it except I store in 440ml screwtop jars. If you continue to pitch onto full yeastcakes you will end up with about 50mm of crud in the bottom of your fermenter. I collect a few jars and then rinse out the fermenter to get rid of the dead yeast and trub.

 

[Nick JD]

I've done it a few times but don't often time it well enough (I don't nochill cube) so I prefer the 300ml trub in PET method and a clean fermenter.

That said - I did find that it suits lager brewing more than ales ... IIRC massivly overpitching is a great way to make a really bland ale in record time.

 

[SJW]

Dont re-pitch onto a full yeast cake, esspecially with an ale, it is over pitching and can be as bad as under pitching. I re-use yeast similar to Kev. Why you would want to pitch a nice fresh clean Pilsner wort into a crappy, cruddy used fermenter with all the **** around the krausen line is beyond me.
Over-pitching is always detrimental to the beer. This does not say the beer will taste awful. Rest assured, however, that if one were to place samples of the exact same beer - one fermented by overpitching and one by properly inoculating the wort - the properly pitched example will taste better. Blind taste tests I have done prove it.

The two most obvious effects of over-pitching are off-flavors. First, yeast material in excess quickly leads to autolysis, which has flavor by-products with very low flavor thresholds. In properly-pitched beers, this effect can take months to show itself. In beers with an excess of yeast solids, it can manifest in a matter of weeks - in fact, the time spent in a home-brewer's primary.

Second, I have observed thin beer, beer lacking in body and mouthfeel. To be perfectly honest, the exact cause of this effect is unknown, but it is strongly correlated with over-pitched yeast, so a connection is highly likely.

Third - and most important is suppression of esters. Yeast rely on the growth phase to reproduce enough cells to fully colonize the wort. In that phase, they use malt-based nutrients and the oxygen you provide during aeration to synthesize the components needed to build new cell walls during reproduction. While they're reproducing they're producing esters. All yeast produce esters, even lager yeast, and all beers benefit from ester production (yes, even lagers). Just because you can't taste as much ester from WLP840 as you can from Ringwood doesn't mean that WLP840 doesn't throw esters! Esters are absolutely necessary to beer, theory about "clean yeast" be damned.

When you over-pitch the colony doesn't need to reproduce. Thus measurably fewer esters are produced. This, while always detrimental to beer flavor, is noticeable in American and English strains and very pronounced with certain more flavorful strains, like Belgians.

 

[Nick JD]

Pitching a 1.090+ wort onto a 1.040 yeastcake is a great idea with Belgians. Solves a heap of attenuation issues (and insane ester levels with 1214) and you get to drink the mild Belgian while you're waiting for the strong.

Pitching onto a yeastcake is not always a bad idea. Sometimes it rocks.

 

[String]

Running out of time today, so I pitched a Skunk Fart Ale straight onto the yeastcake from a Coopers Pale clone. I used 1272 American Ale yeast in the Coopers clone, and couldn't another packet of yeast locally.
I thought it would be fine, after reading SJW's post, I'm not so sure.

 

[Nick JD]

Running out of time today, so I pitched a Skunk Fart Ale straight onto the yeastcake from a Coopers Pale clone. I used 1272 American Ale yeast in the Coopers clone, and couldn't another packet of yeast locally.
I thought it would be fine, after reading SJW's post, I'm not so sure.

Will it be the best beer it can be? Possibly not. Will it be still damn fine? Yes.

A lot of this forum's diatribes are written by perfectionists to whom a missing ester edge or a half inch less head has them tipping the keg on the back yard.

If it's average - dry hop it until it tastes like Starburst lollies.

 

[Liam_snorkel]

I've done it a few of times with us-05 with no discernable[*] problems.

did it once with Nottingham and ended up with beer that tasted like dust. Never again.

the yeast will go off like a bondi tram, so if attenuation & a quick brew is what you're after, go nuts. Yeast this active also produces plenty of it's own heat so maybe set your temp control a couple of degrees lower than your target for the first few days.

my method is now similar to QldKev's.


[*] meaning that my palate is ratshit, and they were pretty hoppy beers.

 

[Diggs]

Would there be lingering hops etc in the trub that would flavour the following brew?

 

[donburke]

if you do repitch onto a whole yeast cake, keep the temp really low as fermentation tends to generate more heat the more yeast there is

i.e. ferment your lager at 7.5, having chilled wort and yeast down to below that prior to pitching

i find repitching on a whole cake provides a real clean taste to the beer, which is particularly helpful if thats what your after, such as in a lager

make sure you still oxygenate/aerate so as to promote growth of new yeast cells to help create some of the desirable flavours generated during the budding phase

plan ahead and make a series of beers, bigger each time

i recently finished fermenting an ipa (1.064) using wy1882, kegged it then onto the yeastcake i pitched a 1.107 barleywine, fermented it at 13.5 degrees (1.5 degrees lower than the recommended lower limit) and it hit terminal gravity in a week

just dont overdo it, as yes, eventually you will end up with lots of dead yeast and trub in the fermenter

in my example above the yeast was used 2 weeks in the first brew and 2 weeks in the second brew, total of four weeks, and just as people say its fine to leave a beer on the yeast cake for 4 weeks or more without autolysis, so to is this method. if you have a normal gravity beer, and enough yeast, a week will generally be enough, and that includes the cleanup

 

[donburke]

Would there be lingering hops etc in the trub that would flavour the following brew?

yes, some of the hop flavour comes through if it was a highly hopped brew and/or there is hop matter in the fermenter, so use common sense here and start with milder brews before stronger hopped ones

 

[pokolbinguy]

I have only re-used my yeast cakes once each (e.g. pitch, ferment, rack, put new brew in, ferment). My tip would be if you want to re-use for a second time, just drain off some of the yeast so the volume isn't to large. Aslong as things are kept clean and your yeast are happy they should be able to ferment a few batches no probs.

The trub will ofcourse retain flavours/aromas of the previous brews which may or may not be friendly in a very different style.

 

[Mr. No-Tip]

Would there be lingering hops etc in the trub that would flavour the following brew?

The one time I did this, I was really surprised how much hop flavour comes through. I was brewing a 8l mini AG batch of generic aussie ale, and pitched onto the cake from a 20l Stone and Wood Pacific clone - a lot of galaxy dry hops. The resultant beer was not what I expected, but a very unique hoppy beer...

 

[Lord Raja Goomba I]

Necro Alert! (are we still doing that here?)

Going to reuse yeast again, once I'm up and running.

Does anyone use the QldKev method (I have) and whack them into stubbies, cap and fridge?

I don't drink coke, so pointless and the next option is use Mt Franklin 450ml sparkling bottles (which we have an abundance of), but would prefer to sterilise with hot water (meaning only glass), not bleach/sodium perc/anything else.

 

[superstock]

Wouldn't the water be sterile? If so pour the water into a glass and use the bottle straight away for yeast.

 

[Coodgee]

what's wrong with starsan?

 

[spog]

Yep I do, I split the yeast cake into 4 stubbies and bung them in the fridge fro next time.
I prefer to use clear glass stubbies for this so I can see what's going on when I tip the beer layer out into a glass for tasting.
If the beer tastes fine it's usable, I let it stand while brewing to bring it up to pitching temp from the fridge then in it goes,rinse with cooled boiled water and job done.
I use 2 stubbies per batch the amount can vary but it's usually about 200 ml in each bottle once the beer is taken off.