multiple wort- pitching on same cake

[count barleywine]

Hey I recently pitched three different worts (strong ale, dark ale, bitter, in that order) on the same yeast cake. When we brewed the next batch, we simply transfered to secondary and then pitched fresh wort into the primary containing the cake. Has anyone done more than two of such pitches? I searched this site everywhere (seemingly) but found no talk of more than two batches on the same cake. Does the yeast lose viability? Attenuation issues? All three beers fermented vigorously, but since they are different styles distinguishing any differences will be impossible unless drastic. Oh yeah the initial cake was a tube of White Labs East Coast Ale yeast, and one tube White Labs California Ale yeast. Battle of the Coasts! Two tubes because the first beer was a strong ale, and also to establish a large healthy cake for multiple pitches. Any insight is greatly appreciated, brosephs.

 

[beeraggie]

I have never pitched onto a yeast cake myself, but a local microbrewery does 10 batches on the same yeast cake before starting over with a new strain of yeast.
They say that they never have any issues with off flavor, mutations, or low attenuation ect.

I say go for it!!!

 

[Yooper]

Most people around here say 3 batches is about it, due to mutations in the yeast. Bigger breweries probably have more control of temperature and other factors, so they might be able to get away with more. I've only done it twice, so I don't know this for fact.

 

[ColoradoXJ13]

Most people around here say 3 batches is about it, due to mutations in the yeast.

People may say that here, but is it scientifically unsound. Personally, I have never done more than two beers on the same yeast, but thats because growing up yeast is free for me. Mutation rates are very slow, and even slower in the coding regions of any genes, especially ones critical to metabolism and life cycle. I'd say keep going and let us know how many you get out of it. I'd be more worried about all the crap you are transferring from one beer to the next in the trub.

 

[Bobby_M]

We've discussed this here recently. It's more a fear of possible contamination, not mutation. If you're absolutely insanly careful with sanitizing everything that comes anywhere near your yeast, you can harvest and reuse indefinitely. The problem with pitching on the cake over and over in the same fermenter is that the neck of the carboy needs to be carefully sanitized without compromising the yeast cake. The other issue is that the cake is made up of a lot of thing OTHER than yeast. Read up on yeast washing. I'm working towards harvesting small portions of the cake, then propagating it via multiple small starters like Papazian writes about.

 

[count barleywine]

excellent insight guys much appreciated. My sanitary conditions are optimal when this takes place, so I will indeed continue and see how we do. thanks again everyone.

 

[Catfish]

I try and reuse the cake from lower alcohol, lower IBU beers for repitching (both tend to stress the yeast). Also I wash the yeast if I am in the mood, or going to be putting it in the zoo to save for future brews.

 

[JimC]

Or you can skip it all and for about $30 get setup to do slants and culture your own. Buy a vial every now and again to add a new strain to the farm and you'll have an nigh infinite supply of home grown yeasties on hand in whatever varieties you decide to keep. Its not to hard to keep everything sterile and it doesn't take much time or effort.

Best of all it costs almost nothing to have quality, risk free yeast ready to go.

 

[Got Trub?]

Catfish raises a good point. If you are repitching you should start with lower gravity brews and move up. There is a limit for the gravity of your beer where it is not healthy for your yeast because of the alcohol and byproducts produced - and its lower then you think. This results in a yeast cake of stressed, unhealthy yeast who are pooped out having just fermented your wort into beer. Also remember that overpitching can be as harmfull as underpitching so just using a whole yeast cake while easy may not get you the best beer possible.

For more and for a handy yeast pitching calculator see: http://www.mrmalty.com/