Pitching Onto A Yeast Cake More Than Once

[Kai]

The only beers with excessive yeast flavour that I have tasted have been ones that have too much yeast transferred to bottle. I've left beers in primary for up to 4-6 weeks at ferment temps without experiencing any ill-effects, and I don't think reusing the yeast cake would be a problem with regards to autolysis. Only caveat is that I would never reuse the entire cake, only a cup or two of slurry.

 

[Jens-Kristian]

Thanks for the info.

I don't have a brew I'll be able to repitch on at the moment, but I'm planning on brewing a porter within the next few days, using WLP023 Burton Ale yeast from White Labs to get some of its fruity flavours. After that I have an ESB planned and I was thinking I may very well pitch on the cake. Alternatively I may do as Duff suggested and simply get a bit of the slurry from the tap and keep it in a bottle for a bit.

Another thing is, Ross, you mention getting 10 starters out of a liquid yeast. How do you go about it? What I mean, can you just pour a bit from the vial into a starter and then re-cap the vial and put it back in the fridge 'as though nothing has happened'? So far, I've only done about a brew per month because of time, so if that's a way to do it that would be wonderful. I am looking at stepping up my productivity a bit though! :beer:

It's not really the cost of the yeast that I'm on about with all this. I agree that it is after all relatively cheap to get a new yeast - it's more that I like the whole process of fiddling about. As you can hear I've never really done this part of it before, but it sounds like fun.

Cheers,

Jens-Kristian

 

[Ross]

Another thing is, Ross, you mention getting 10 starters out of a liquid yeast. How do you go about it? What I mean, can you just pour a bit from the vial into a starter and then re-cap the vial and put it back in the fridge 'as though nothing has happened'?

[post="129727"][/post]​

Jens-Kristian,

The method i use & others techniques here. Quite a few threads on yeast farming if you dig around.

cheers Ross

 

[Jens-Kristian]

Thanks, Ross.

I'll dig around in that.

Cheers,

Jens-Kristian

 

[T.D.]

I currently have my 15L cube of bock in the fridge. I'll pitch it on the 2-brew-old yeast cake this afternoon. I think its fine that people have a "once only" policy, but it is comforting to hear that other people have pushed it further and have not had any really adverse effects on flavour. I'll try to remember to post back here with my findings.

In my case GL's comment about weighing up the benefit of high yeast numbers against the negatives seems very relevant. This is a traditional style bock with OG or around 1.068 and plenty of darker malts in the grain bill. If there's a beer out there that needs a BIG yeast starter, this one may well be that beer!

 

[sah]

I don't have a brew I'll be able to repitch on at the moment, but I'm planning on brewing a porter within the next few days, using WLP023 Burton Ale yeast from White Labs to get some of its fruity flavours. After that I have an ESB planned and I was thinking I may very well pitch on the cake.

[post="129727"][/post]​

Jens-Kristian,

This is the yeast I've got working on an ESB now and the cake is then going to be put to work on a brown porter and then if I'm feeling a bit daring it'll go to work on a stout.

This is really nice yeast and even though I've got it in the farm its a shame not to get the most out of it

All the best.

Scott

 

[Trough Lolly]

So, everybody says, "don't leave a beer sitting in the primary fermenter for longer than 2-3 weeks" because you may subject yourself to autolysis.

For my last lager, I couldn't bring myself to throw out all that nice yeast sludge (Saflager 34/70), only to brew another lager and have to pitch 2 new sachets on it. Surely the yeast cake left from the previous lager would be like a "super starter". So I pitched my latest lager on the yeast cake and it went like a dream, tastes great out of the fermenter etc etc. I now have a bock that I want to ferment. Its obviously high gravity, so a good dose of yeast is preferred. At this stage I am going to pitch the bock on the yeast cake, which will make it the third brew in a row on that yeast.

Am I subjecting myself to autolysis by doing this? Is what I am doing sort of like leaving a beer sitting in primary for 6 weeks (3 brews X 2 weeks each)?

How many times can you safely pitch a new brew on the yeast cake of an old one?

Cheers :beer:

G'day T.D.
I blabbed on about auto self lysis splitting, aka Autolysis, in this post back in April... In that post, I mentioned that autolysis generally occurs when the yeast cells run out of sugars to consume and in survival mode, the yeast cell enzymes break down (self lysis) the structural molecules in the cells themselves, in order to acquire more nutrients...
I would agree that leaving fermented beer on a yeast cake in the primary fermenter _may_ place the beer at risk of being affected by subsequent yeast autolysis, but that assumes that the yeast does in fact go into autolysis. And this risk is something that we brewers accept whenever we put yeast slurry into stubbies under fermented beer or cooled pre-boiled water for long term storage...A good way to mitigate that risk is to put the stubbies of yeast into the fridge to cool the solution and get the flocced yeast cells dormant during storage.

Getting back to your original question, I repitch onto my yeast cake quite regularly - assuming that I'm wanting to ferment my next batch with the same yeast strain. So far, I've managed to avoid infections and autolysis in my last 10 or so years of brewing...Now, I'm no chemist but from what I've read and researched on this topic, you would reduce the risk of autolysis if you repitched fresh wort onto the yeast cake since you've supplied a nutrient medium for the yeast to get at and thus the cell enzymes do not need to self destruct the cells in order to acquire nutrition. I would suggest that you are at greater risk of yeast mutation delivering unexpected results from repitching, rather than autolysis, but that's another story altogether. On other forums I have read of experienced brewers who do accuse the W34/70 strain of being quite capable of mutating in an undesireable way, when it's repitched on a number (4+) of occasions. I agree with Ross, repitch away a few times, but after the 3rd pitch, I'd look for fresh yeast elsewhere...

Cheers,
TL (From the Qantas club in Adelaide!)

 

[T.D.]

Thanks TL, great info! That makes a lot of sense now that its been spelt out to me! As long as the yeast always has sugars to eat up, autolysis should not be an issue. But yeah, as you say, the mutation factor then comes into play. After my bock I will use a fresh strain of yeast for future lagers. The bock is the third brew in a row on the same yeast. I was drinking the pilsner (2nd brew on the yeast) and its tastes great - it tastes in no way different to how I would expect it to be if it was fermented with fresh yeast. I haven't tastes the bock yet so I can't comment on that one. It certainly is an economical way to brew. I know dry yeast is relatively cheap, but when you have to use two sachets in each lager it gets pretty pricey! If you can squeeze 3 brews out then you are back to around $3/batch which is pretty good.

:beer:

 

[adamg]

We generally try to use the same yeast cake twice at a minimum, after the beer is racked to the secondary we scoop out about half of the yeast then add the next batch of wort to the fermentor with the remaining yeast. We only remove yeast to limit the mess made bubbling through the air lock and into the fermenting fridge. Although now we have a tube from the fermentor to a 2 liter soft drink bottle half filled with water as an air lock and it seems to catch the mess. The money saving is not massive, but the time saved not having to do starters is priceless!!

Adam

 

[lpa]

And the beast fermenting away within minutes of pouring the wort in is a real bonus too. I've just dumped a cheap Cooper's bitter with 50/50 blonde LM and Dex onto a pile of very nice looking Safale lees just to see what would happen and it's all been pretty exciting. Winter's a bit colder here in NZ and the 15-24deg ideal range for the S04 is pefect in the laundry cupboard (big). I found it took a good 24 hours to start if sprinkled, which was frustrating, so this crazy business is attractive. Got an inch of trub now though. I decided that lager to ale to dark was a good plan and it's nice to know there are others out there doing stuff which probably freaks some of the more sensible brewers...

 

[Stuster]

Don't think it freaks out the sensible brewers. They are doing this too. White labs recommends up to 6-10 generations. (probably fewer is better due to the chance of contamination in our systems). I tend to do runs of 2 or 3 and then move onto another yeast. ADHD perhaps.

Anyway, this quote is from the White labs site.

How many generations should I use my yeast?

We recommend 6-10 generations per strain. Three main reasons yeast should be replaced on a regular interval are bacterial contamination, yeast cell mutation, and yeast fatigue.
Bacterial contamination is largely responsible for off flavors. Bacteria grow at an exponential rate in comparison to the yeast.
Yeast cell mutation. Yeast cells will adapt to their environment, this could dramatically or subtly change the characteristics of the beer.
Yeast fatigue. Beer is a hostile environment for the yeast. Healthy yeast requires oxygen and food (malt). CO2 and alcohol are detrimental to the overall health of the yeast.

adamq, probably best to use only part of the yeast cake as you are doing, not only for the mess but to give the right ester profile. too much yeast can give a bland beer IIRC. This page will calculate how much you need. Much easier than making starters every time I agree.

 

[Trough Lolly]

Repitching fresh, clean wort onto a well managed yeast cake is a sure fire way of getting to the attenuative phase without a prolonged adaptive phase (lag). It also helps to "overpower" the presence of any potentially infectious bacteria that may want to dominate the wort composition.
As an aside to the original post, it's often argued that certain strains, and particularly some commonly used lager strains, actually benefit from repitching. I'll see if I can find the actual threads that refer to this, on overseas commercial brewing forums, but the line of argument suggests that the repitching actually helps the more viable cells in growing in population and further improving the quality of the fermented product. The "tired", stressed and potentially mutatable (?!) cells don't grow at the same rate and you end up with superior beer.
I can see the logic in this argument, but my concern is whether the repitching is actually "pushing" the growth of cells that happily go for the readily fermentable sugars in the wort and are "lazily" avoiding the more complex maltose based fermentables that give us a more complete flavour profile, usually after extended conditioning. This is often noted with the cheaper kit based dry yeast sachets that do a good job at attenuating the wort, but don't give the complex flavour profile that you can obtain with a dedicated dry or liquid yeast strain, or from slants or stepped up single colony starters, etc...
Cheers,
TL

 

[goatherder]

Don't think it freaks out the sensible brewers. They are doing this too. White labs recommends up to 6-10 generations. (probably fewer is better due to the chance of contamination in our systems). I tend to do runs of 2 or 3 and then move onto another yeast. ADHD perhaps.

Anyway, this quote is from the White labs site.

I've been listening to a Basic Brewing Radio podcast where there is a 3 episode interview with David Logsdon from Wyeast. He agrees with this point, although he distinguishes between ale yeast and lager yeast. He says that lager yeast is only good for 3 re-pitches where an ale yeast can handle up to 10.

 

[RobboMC]

How long does one have to get the next batch going?

I once successfully farmed up some yeast from the bottom of a bottle of Coopers Pale Ale. First brew was successfull, so I thought I would re-use the yeast, but when I tried to save some of the yeast cake and repitch it didn't work.
I scooped up about 500 ml of the yeast cake into a sealed plastic bottle and kept in fridge overnight, then repitched the next day - nothing happened.

48 hours later I decided to act, so I sprinkled in some dried yeast through the air lock hole and next day I had proper fermentation, so there was nothing wrong with my second wort. Beer turned out great.

Any ideas what I did wrong?
Should I have stored at room temp?
Should I have added some malt?

 

[Finite]

How long does one have to get the next batch going?

I once successfully farmed up some yeast from the bottom of a bottle of Coopers Pale Ale. First brew was successfull, so I thought I would re-use the yeast, but when I tried to save some of the yeast cake and repitch it didn't work.
I scooped up about 500 ml of the yeast cake into a sealed plastic bottle and kept in fridge overnight, then repitched the next day - nothing happened.

48 hours later I decided to act, so I sprinkled in some dried yeast through the air lock hole and next day I had proper fermentation, so there was nothing wrong with my second wort. Beer turned out great.

Any ideas what I did wrong?
Should I have stored at room temp?
Should I have added some malt?

By storing the yeast in the fridge then throwing them straight into a warm wort you have given the yeast thermal shock.

Shifting the temp of a yeast culture 13c will result in a 85% decline of cellular levels

In the future remove the yeast from the refrigerator approximately two to six hours before pitching and allow the yeast to come up to room temperature before pitching.

If you are freezing your yeast for long term storage you are better of dividing them into small sanitized test tubes or containers with a 50/25/25 mix of yeast, water & glycerine, this stops the cell walls from rupturing while frozen.

Links on freezing yeast:

http://www.schwedhelm.net/brew/yeast_harv_freeze.html
http://www.aussiehomebrewer.com/forum/inde...=freezing+yeast
http://www.aussiehomebrewer.com/forum/inde...=freezing+yeast
http://www.aussiehomebrewer.com/forum/inde...=freezing+yeast

 

[Trough Lolly]

G'day RobboMC,
There's actually a number of potential reasons why the harvested Coopers culture may not have "worked"...
The yeast may have been stressed out after being harvested and put to work. This of course assumes that the actual pitch size was small, and 500ml is a bit light on particularly for a high grav beer...
If you were going to repitch the next day, I would have tried to plan the brew day so you repitch straight after you racked the beer off the yeast cake - and you can either pour the fresh wort directly onto the yeast cake or take some of the cake and add it to the wort in a fresh, clean fermenter. I do this during the boil or chill stage so the beer is racked off the cake, leaving a small barrier of beer behind so the cake is not in direct contact with the air, and the chilled wort is added soon thereafter either on top of the old cake or in a new fermenter with some of the cake added.
The yeast would have experienced some shock when you refrigerated the slurry and then added the bottle of cold nutrient depleted slurry to the fermenter, all within 24 hours.
Cooling the yeast not only affects the cells - it also has an impact on the levels of UFA's (Unsaturated fatty acids) and other important elements, including trehalose and glycogen etc in the slurry. The yeast is about to go into dormancy and it's own self preservation mechanisms kick into gear when this happens - kinda like a bear having a feed before hibernation.
And finally, who says the slurry didn't work! When you pitched the dry yeast, the slurry may have been nearing the end of a 48 hour adaptive phase where it was actually growing in population before launching into the attenuative / fermenting phase?
Cheers,
TL

 

[Steve]

Robbo - you just put the yeast to sleep. You should have brought it back up to room temp and then made a 1.5l starter with it.
Cheers
Steve

 

[Trough Lolly]

....or take the 500ml of slurry into a 3L Pet bottle or sherry flagon when you did take some slurry and add a litre of fresh 1.040 starter wort (using LME or DME) to let it get active overnight for the following brewday and then you would have pitched an active starter and had almost instant action!

Cheers,
TL

 

[Steve]

I would be more inclined to use just a cup full of slurry instead of 500ml....you may blow the airlock off without a blow off tube with 500ml.
Cheers
Steve

 

[Ross]

And finally, who says the slurry didn't work! When you pitched the dry yeast, the slurry may have been nearing the end of a 48 hour adaptive phase where it was actually growing in population before launching into the attenuative / fermenting phase?
Cheers,
TL

I agree with TL's last paragraph - 500 ml of 24hr old slurry would need more than a thermal shock to stop it completely - Patience grasshopper ...


cheers Ross