# How many times can you reuse your cake?



## Dave70 (30/4/13)

I can't say I know much about the life and times of yeast outside the basics, but I'm assuming there must be a catch to reusing the same lot over and over, even if you went to the trouble of washing it and making a starter. Or is there?
Now I can use my keezer strictly for the kegs, I'd like to have a house beer tucked away along side whatever else I'm having a play with. So I'l be making the same style of beer pretty much over and over until I'm bored with it, and if it was the last Saison I made, that could be quite a few months, and thus, quite a few bites at the cherry, yeast wise.

Will the yeasties eventually just clap out and under attenuate or simply begin throwing off flavours?


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## adryargument (30/4/13)

Mutates into large hibernating bears.

Why not buy some glycerin from your chemist and 'save' a few vials of the first batch of yeast?
Then you can reuse indefinately.... well until it all turns into bears.

Then buy a shotgun.

Edit: Mutating bears can give off bad flavours, behaviours, etc etc. i.e. top cropping only will result in under attenuated bears, bottom cropping will result in over attenuating bears. Middle cropping will result in bears with ak-47's and a craving for vampire blood.


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## Yob (30/4/13)

I once visited the Franciscan Well Brewery in Ireland.. he was up to 128 pitches from batch to batch in a commercial environment... erm.. not incerdibly scientific about it and the disclaimer is that it was the same beer again and again..

still... 128.. Got a photo somewhere with the recipe and that number on it.. will try and dig it up


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## treefiddy (30/4/13)

adryargument said:


> Mutates into large hibernating bears.
> 
> Why not buy some glycerin from your chemist and 'save' a few vials of the first batch of yeast?
> Then you can reuse indefinately.... well until it all turns into bears.
> ...


Wat?!

I've done 5 generations (repitching directly on yeast) with success.


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## adryargument (30/4/13)

treefiddy said:


> Wat?!
> 
> I've done 5 generations (repitching directly on bear) with success.


Yep, i have done the same.

However certain scientists who own whitelabs with a book called 'yeast' recommend a maximum of 5-7 reuses's of bear cake - someone correct me if im wrong, going off memory here.

However it all comes down to your cleanliness, style of harvesting etc. As Yob said, it could be negligeble changes, however they could also be vast. Then again over 128 brews how can you keep track of subtle changes unless you have original brews to compare it to (even these would have some sort of aging flavours)??


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## iralosavic (30/4/13)

I have nothing scientific to offer, but I'm a big yeast cake re-user myself and never noticed any negative side effects over 3 or 4 generations. I heard of people discarding a portion of the cake in order to prevent over-pitching, but I've never done that as I generally plan progressively higher gravity brews each time.


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## Yob (1/5/13)

The brewer admitted that the flavour profile of the yeast had 'evolved' significantly over those 128 uses but in a good way, the only time to stop using yeast is if flavour drift starts moving in a direction you are unhappy with or you get to a high alcohol brew which makes for sad little yeasties.. That is, if your sanitation is up to par and infection isnt an issue.

The brewer said that he was going to 'reset' the brew (a wheat from memory) at some point and was worried about how the locals would take it.

Gunna have to get me a microscope one of these days..


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## DennisKing (1/5/13)

Recently I've been getting yeast from a local brewery here in the UK. The brewery, Crouch vale in Essex brew with the old Ridleys strain, historic strain from the sadly missed Essex brewer, Whitelabs Essex strain is reputed to be the same but the live version I've found to be far superior. On my last visit the brewer told me in the three years he had worked there they had never washed or rinsed the yeast. Just top cropped and reused. As an experienced professional brewer he was surprised when he first joined the brewery. Twice in fairly recent years this brewery has won the CAMRA supreme champion UK beer at their annual national festival.


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## NewtownClown (1/5/13)

Cropping during High Krausen and re--pitching the yeast cake after fermentation is complete are different. 

I would happily crop and pitch 128 times if I had the brewhouse capacity to do so. However I would not re-animate a dormant yeast 128 times. One paper has shown Saccharomyces Cerevisiae to evolve from a single-cell organism to a multi-cell ones in which some of the cells have "given up" certain abilities (reproduction) for the benefit of the rest, (prompting evolutionary science to re-think the time frame for the leap from single- to multi-cell evolution on earth).

Published in the journal Proceedings of the National Academy of Sciences (PNAS) circa January 16 2012 .


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## punkin (1/5/13)

I have pitched onto the lees many, many times on a corn based beer that i only wanted the steam from. Well over fifty, probably over 100 times. Yeast worked fine and was actively fermenting with in the hour. Flavours developed in a differnt direction after a few pitches but that was due to the recipe rather than the yeast mutating i believe.

That being said i tend to stick to 4-5 times for beer.


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## QldKev (1/5/13)

I reuse my yeast until I want a different strain going (or I suspect a hint of infection). I do run 3 fermenters at a time so I do have 3 yeast choices on the go. I've had some yeast cakes running for over 6 months at a time without ever being washed. I've never found any 3 eyed monsters.

QldKev


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## Womball (1/5/13)

I'm the same as QldKev, but I generally wash/reuse. The only time I'll step up a new batch of yeast from a slant is if I've stressed the yeast out with a high ABV beer or dry hopped the hell of out of in the fermenter (which is rare, as I normally dry hop in the keg on secondary and off the yeast, but I have a tendency to run out of keg space)


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## Bribie G (1/5/13)

At the Brisbane Conference a couple of years ago the guy from Whitelabs said that using subsequent generations of the yeast helped it to "settle down" to style, and that the first generation from Whitelabs vial is often a bit lacking in character but once the yeast is exposed to the specific ingredients it becomes more characteristic with production of esters, whatever it's thang is.

On the other hand at that same Conference I bought a vial of San Diego Super Yeast and it went great guns for four generations, then stopped being super and was almost indistinguishable from US-05 so I stopped using it.

I go around 3 generations and take 2 x 600ml brand new and emptied mineral water bottles of trub which I just store in the fridge. That way if I run into problems say with gen 3 I can go back to gen 2.


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## drsmurto (1/5/13)

Yeast is cheap.

I aim for 2 beers from 1 smackpack or vial. Anymore is a bonus.

Everytime you make a starter, wash a yeastcake, repitch used yeast, you are increasing the risks of an infection or the yeast not behaving the way you want it/expect it.

2 beers per pack/vial is the same cost as a pack of dry yeast (or thereabouts). ~$5 of yeast per beer.

Cheap insurance in my book.


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## 431neb (1/5/13)

So disappointed. Who edited the "Yeast Police" comment. That was priceless.


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## Nick JD (1/5/13)

From a smackpack, I usually get 6-8 batches.

Split into 3 or 4 starters ... trub spitched once each.


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## mckenry (1/5/13)

i split 3 ways from new and just make 3 starters and get three brews. Always using a 'new' one then and its $3 per brew. Starter made from mash runnings last brew, so 'free'
I used to try to make it last by keeping slurry and rinsing, until I looked at the cost v effort.


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## Liam_snorkel (1/5/13)

431neb said:


> So disappointed. Who edited the "Yeast Police" comment. That was priceless.


Same topic, different thread: http://aussiehomebrewer.com/topic/63344-a-new-dry-yeast/?p=1026295


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## Dave70 (1/5/13)

431neb said:


> So disappointed. Who edited the "Yeast Police" comment. That was priceless.


*_The yeast police, they live inside of my head* _ Ha! _Sweeet.._


I'm happy to split a pack, then get a couple of goes at the cake. Sound's like a happy medium.
By then I'll be moving on anyway.


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## Phoney (1/5/13)

I split 5 ways (4 vials and 1 starter). Then occasionally reuse cake if im brewing something similar.

Using this rule I still end up with vials of 2 year old yeast hiding at the back of my fridge that end up getting tipped so I reckon i've got it just about right.


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## Grainer (1/5/13)

Being a Geneticist/Microbiologist in a past life I would say 5-6 pitches from the same yeast would hold true if this was a cell line.. but it is not.. it is a yeast! I would say that best practice would to use a primary culture that is uncontaminated and use this as a benchmark for further brewing. but we dont all have the right facilities.. so it makes it a bit more difficult. This would need to be recultured probably fortnightly...ideally frozen down..although be aware that -20dec can cause shearing of the cells and kill them.. even in glycerol....-80 is better... In most cases 1-4 degrees would be best considering resources available. If it was me I would keep a primary culture in glycerol at low temps and then use this primary innoculum as the golden child for further brews. I would then not touch this unless I needed to and subculture maybe every 2-4 months.. but i would need to experiment with this. (I have always had access to -80 or -196 deg cryopreservation for free... Then I would set up a secondary innoculum and use this to set up all other batches. You only need a drop in your starter cultures.. start with 50mls of yeast nutrient solution and then upgrade it to a 100ml-200ml innocculum. and your off and running. best is to do this over 12 - 30 hours at the desired temp on a mixer depending upon the yeast requirements.... any longer than this and you may see a decline in the yeast health due to the introduction of yeast byproducts.

The problem with reusing the yeast for more than approximately 8-10 generations is that it can slightly change the genetics of the yeast and it can also change the efficiency of yeast division/growth and alcohol conversion. It is important to note that all strains of yeast are different and each will have specific requirements.

In addition, it does matter where you collect the yeast.. Early settling yeast may not be good at producing alcohol and same as the last sediment, however the middle yeast tends to be better at alcohol conversion. Skimming of the top or bottom will change the beer characteristics in time.

If it was me I would skim from the middle re-culture this to get a healthy culture and then store this under sterile conditions if you can.

Once again just my opinion.. they key in all of this is to have yeast at its earliest generation with a healthy, young culture for best results.

cheers


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## Dave70 (1/5/13)

Grainer said:


> I have always had access to -80 or -196 deg cryopreservation for free...


I bet you could produce a cracking Eisebock. And quickly.


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## verysupple (1/5/13)

Going along with the general consensus of the replies...it depends. Back in the day (before they knew that yeast existed), brewers used 100's of generations of yeast. Things have changed, though (pure cultures etc.). As quite a few other posters, my knowledge comes mainly from "Yeast: the practical guide to beer fermentation" (White and Zainasheff). My understanding is that the point at which you harvest the yeast (so this means not dumping wort onto an entire cake) is critical - because of selective pressure (genetics mumbo jumbo - Google it). I'll assume from the use of the word 'cake' that ur bottom cropping in which case, as many texts have advised, you should take the middle layer of the cake for harvesting. This will limit the deviation in character (both attenuative and flavour-wise) of subsequent generations from the first and maximise the number of generations you can use.

Of course, if you are dumping on the entire cake, there are so many factors that affect the beer it's almost impossible to determine what's affecting the flavour.


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## verysupple (1/5/13)

Grainer said:


> I have always had access to -80 or -196 deg cryopreservation for free...


Ha, you got Luke Skywalker trapped in there? 

But seriously, other than you, what kind of homebrewer has the ability to handle cultures like that? Even Siberia isn't that cold.


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