Reusing yeast in a Sanke fermenter

[joeybeer]

I like to brew (and drink) many different styles of beer, but one that I have to keep on hand is a Light American Lager style Ale, brewed with US-05. I've been brewing all grain for over a year & feel like I have this figured out pretty well..

My question is, I'm fermenting 10g in a Sanke keg, the first 2 days with an airlock and the next 8 under pressure. After 10-14 days it is racked with CO2 to a serving keg. Recently I got the bright idea of not cleaning the fermenter between batches, it's purged with CO2 when filled, and stays that way and at temp (60F ambient).

I'm not afraid of going over a certain number of yeast generations, but wonder about buildup of dead yeast and trub, I drain the Sanke down to 2qts remaining, leave it sealed and pour the next batch right on the old cake. Needless to say it goes off like a firecracker as soon as the new batch goes in.


Anyone see a problem with this ??? It tastes great and allows me to have huge amounts of beer for anyone to drink on tap all the time, even the dreaded BMC drinkers

~Joey

 

[FarmBoy530]

I would pull the yeast and rinse it if i planed on reusing it. Only recycle a few times, maybe 5 tops. Also be very sani when working with your yeast! But if your reusing you want to rinse away all the dead yeast and hop and protein and tannins and dead bugs and anything else that may have fallen out! This way you only repitch good yeast.

 

[erikhild59]

I routinely pitch on cakes. I usually do 5 5gal batches on a cake. Never had a problem with sanitation or off flavors. I do this in a carboy, with some exposure during transfer, but I feel like if the first batch is clean, the rest will be as well. If you're operating in a sealed vessel, I think you'll be golden.

 

[joeybeer]

Erikhild - do you notice a buildup of trub after the first couple of times ?? Does it double in size each batch ??

 

[FarmBoy530]

I'm not in any way saying you cant brew good beer with a repitch on trub. I will say that it is not possible to brew the best beer you can by just repitching on trub. Since rinsing is so easy, to me its a no question. Jamil and John even refer to it as "lazy". You spent so much time money and effort brewing why skimp when it comes to the most important ingredient in your batch?

 

[erikhild59]

Erikhild - do you notice a buildup of trub after the first couple of times ?? Does it double in size each batch ??

Yes there is a sizeable buildup by the end of 5 batches. Not sure that it doubles every time but there is a lot. Most of it becomes compacted at the bottom and doesn't even get disturbed during fermentation.

 

[erikhild59]

I'm not in any way saying you cant brew good beer with a repitch on trub. I will say that it is not possible to brew the best beer you can by just repitching on trub. Since rinsing is so easy, to me its a no question. Jamil and John even refer to it as "lazy". You spent so much time money and effort brewing why skimp when it comes to the most important ingredient in your batch?

I have to ask if you've ever tried multiple batches on a cake. I've pitched big starters, I've washed yeast, I've brewed the same batch with different methods , and I can tell you that big starters and washed yeast don't make the "best beer". Based on experience. Beer has been brewed this way for ages, and while some may say its lazy, results speak for themselves.

 

[midfielder5]

I read recently that about 4.5 tablespoons of freshly washed yeast gives you ~200 billion yeast cells, which is what you need for 5 gallons of a regular OG beer (give or take given how much yeast is there vs trub, etc.)

So a full yeast cake is, like what.. four to ten times that? (I have not measured it).

I like fresh & basically "free" yeast, but I always do a simple wash: boil 1 gallon of water, let it chill, dump water onto the cake in my bucket, let the trub settle our and jar up mostly only yeast.

edit: I have not done what erikhild59 suggests. Of course, everyone is free to do what they want/ whatever works. cheers.

 

[FarmBoy530]

I have to ask if you've ever tried multiple batches on a cake. I've pitched big starters, I've washed yeast, I've brewed the same batch with different methods , and I can tell you that big starters and washed yeast don't make the "best beer". Based on experience. Beer has been brewed this way for ages, and while some may say its lazy, results speak for themselves.

To me what you said doesn't make sense. If "big starters" (assuming this means more then the proper amount of yeast or it would be a proper size starter) Don't make the best beer, why would way over pitching on a 1/2 dead yeast trub? Also, if you like repitching on an old yeast cake why not clean that dead yeast out? Get rid of all that protein and crud, then just pitch on the clean yeast. Its the same yeast that's in your old trub, only its cleaner. Why is old trub good and clean yeast from that same trub bad? + you can reuse rinsed yeast for more pitches then pitching on a trub. I just don't understand how anyone sees more benefits from pitching on trub then rinsing. aside from it being a short cut. Oh yes, and if things were done the way the have always been done we would still be hunting game with spears and eating berries.

 

[erikhild59]

By big starters I mean the maximum recommended cell count. As far as washing goes, the yeast never ferment vigorously (at least for me), and a quickly begun, vigorous fermentation is key to good flavor. I think the cake also helps clean the beer up at the end of the primary. As for overpitching, maybe on the last few, but I've seen no detrimental effects , and would rather over- than under-pitch. And for the hunting and berrypicking, I'm pretty sure they were healthier than the burger and fries eating public at large.

 

[FarmBoy530]

Yea you got a point with what we eat today. But I'm still not convinced that any part of the trub helps clean up the beer other then the still active yeast. Most home brewers and brewery's note that the 2nd to 4th time they rinse/wash a pitch, its at its peak. My last rinse and repitch started bubbling my airlock in just under 3 hours and was done in about 2 days. I left it for 2 weeks to clean up in primary. It is a very debatable issue but I truly think this is the best way for me to make the best beer I can possibly make. I also think a proper size starter made correctly will be almost if not just as good.