Continuous use fermentation?

[Dland]

Just wondering how long/how many batches others have gone with same yeast in fermentor. I had gone up to three before several times, and I just went four batches, and when I went to clean fermentor, there was no indication in appearance or smell I could not have gone further, and the last batch was racked over a week ago.

Does anyone use a "continuous use" protocol, like they do in some food processing plants (and for all I know, some breweries) ? I know a lot of brewers preserve their yeast for brew after brew. This is sort of the same thing, but yeast remains in sealed fermentor.

I have conical fermentors, so I can dump trub & solids, and temp control, so yeast stays at optimal temperature. I'm kind of tempted to see how long I can go, or at least until I want to change yeasts. I'll be doing low temp lagers for a while, so regular brew schedule of every other week will work out well.

Benefits: Cleaning fermentors is a chore, and it saves buying yeast and fussing w yeast. After initial pitch, there is not even a need for a starter or special care of yeast cake, as conicals hold about a liter of yeasty beer below racking valve.

 

[OldDogBrewing]

You can try using it for the same beer, with time it will adapt better to what you're brewing

 

[mashpaddled]

As long as you can avoid a low level infection slowly building in successive batches--which is almost certain to eventually happen with time--and you aren't concerned about any flavors carrying over from batch to batch, the problem you'll run into is krausen rings inside the conical will keep building up and will need to be cleaned. Unless you only ever transfer under CO2 pressure you run the risk of mold growing on them.

But if you're only talking about brewing a handful of successive batches between cleanings these are not significant issues.

 

[Dland]

Looking at the fermentor I just opened after four batches, there was only the krausen ring at top, last batch being fairly high volume, no rings from previous batches. I only ever transfer w CO2, so no O2 should be introduced except w new wort. Blow off tube always in starsan.

My concern is of course an infection getting introduced, but saw no sign of one. I have yet to have one in low temp lagers, the only infections I have ever had have been w ales, not sure why. 2/3 of what I brew are lagers, and now cellar is cooling off, will be running them until next spring.

 

[bracconiere]

My concern is of course an infection getting introduced, but saw no sign of one.

i usually get a year. or 50 repitches, the only time i've gotten 'bad' infections i.e. 'sour'. is when i actually sanitize the fermenter, all i do is pasturize.

 

[Calder]

You can reuse yeast for as long as you like, so long as it doesn't get infected. It will change over time, due to your practices being selective of yeast cells with certain characteristics (higher/lower attenuation, flavors, etc). You should not see any real differences in the first 5 to 10 re-pitches.

 

[norrismj]

I am curious in this process can you tell us how much of the trub and spent yeast do you purge from the fermentor? How much do you leave behind for the next batch?

 

[Dland]

I usually do a trub dump the day or day before racking to kegs, both to remove trub and take a gravity reading. Usually trub dump volume is about a quart. The amount of solids seems to vary some, but the dump seems to remove what has collected at bottom of fermentor. When settled, the solids often make up about half of the quart dumped.

The volume of fermentor between the racking and dump ports is also about a quart. This is what is left behind as yeast source for next batch of wort. The batches I make a usually put between 10 and 11 gallons of new wort into fermentor, so the amount left behind is not enough to affect the character of next batch much.

While I am intrigued by the possibility of yeast selecting for a my brews, I probably would not go long enough between fermentor sanitations to develop anything very far from what is originally pitched. Right now I'm running S-189. Since I ferment inside the recommended temp range, and usually have starting gravities between 1.050 and 1.060, I doubt I'll notice much deviation.

 

[Dland]

Thought I would update & report on this subject. I brewed 7 continuous 10 gallon batches of lager without opening or cleaning fermentor. All the batches came out fine and as expected, no downgrade in quality. Besides the first batch with initial pitch, fermentation started up fast and went quickly, for a low temp lager, having the same effect as the much touted "overbuilt starter" w no extra effort.

I decided to sanitize it and pitch new yeast today since it had been a month since I had brewed (due to snow & ice in brew area), and the container of starsan the blow off tube was in had mostly evaporated, possibly letting air in. But by the look and smell of the yeasty beer, I'm pretty sure it would have been OK to keep going.

The krausen ring at top of fermtentor was pretty dry and hard, since it had been nearly empty for a month, I had to use a plastic windshield scraper to get it off, but otherwise cleaned up fine.

Attached is a picture of fermentor when I opened it today. I intend to repeat procedure and see if I can go until I decide to switch yeasts.

 

[bracconiere]

i'd just ask, would your fermenter be feasible as a HLT for sparge water? (and that looks like my fermenter, but mine's HDPE. about ready to rinse it and put my sparge water at 180f in it. lid it up and wait till it's 168f or so.....

 

[OldDogBrewing]

Thought I would update & report on this subject. I brewed 7 continuous 10 gallon batches of lager without opening or cleaning fermentor. All the batches came out fine and as expected, no downgrade in quality. Besides the first batch with initial pitch, fermentation started up fast and went quickly, for a low temp lager, having the same effect as the much touted "overbuilt starter" w no extra effort.

I decided to sanitize it and pitch new yeast today since it had been a month since I had brewed (due to snow & ice in brew area), and the container of starsan the blow off tube was in had mostly evaporated, possibly letting air in. But by the look and smell of the yeasty beer, I'm pretty sure it would have been OK to keep going.

The krausen ring at top of fermtentor was pretty dry and hard, since it had been nearly empty for a month, I had to use a plastic windshield scraper to get it off, but otherwise cleaned up fine.

Attached is a picture of fermentor when I opened it today. I intend to repeat procedure and see if I can go until I decide to switch yeasts.View attachment 720466

This is how Orval used to brew, but in an open fermenter, and that's how they ended up adding Brett because when they cleaned and sanitized the fermenter the beer lost it's character, just a fun fact

 

[Snuffy]

When you add the new wort to the fermenter on top of the previous yeast cake, do you attempt to disturb it as little as possible or do you add it where it mixes freely with the previous yeast?
Also, what would you consider the maximum amt of time you would be comfortable waiting between batches?

 

[Dland]

When you add the new wort to the fermenter on top of the previous yeast cake, do you attempt to disturb it as little as possible or do you add it where it mixes freely with the previous yeast?

Wort gets pumped down from ground level to fermentor in cellar during cooling, so it is pretty well mixed.

 

[Dland]

i'd just ask, would your fermenter be feasible as a HLT for sparge water? (and that looks like my fermenter, but mine's HDPE. about ready to rinse it and put my sparge water at 180f in it. lid it up and wait till it's 168f or so.....

Would not make good HLT, just a thin walled stainless conical.

 

[Barbarossa]

Dr Hans made a video where he reuse the same fermenter for a year.

 

[Snuffy]

Wort gets pumped down from ground level to fermentor in cellar during cooling, so it is pretty well mixed.

sorry - i was imagining this on an entirely incorrect scale.

 

[kpsalerno]

One comment I have is are you measuring how much of the yeast cake you repitch into each new batch? It sounded like you do, since you draw off the trub with the value at the bottom of your canonical, but wasn't explicitly stated how much you repitch. I typically save more than 32 oz of yeast cake after a batch, but only need 8 oz of Ale slurry / 16 oz of Lager slurry to repitch for a new standard strength batch. I have a friend who just pours wort on top of the yeast cake without any harvesting or measuring slurry first and he seems to get good results, but I would imagine that is way over-pitching and you could miss out on desirable esters. My friend's beers tend to be very hoppy IPA styles where you don't miss the esters anyway, but I tend to brew maltier beers that would be hurt by over-pitching, so I pay attention to how much slurry I repitch. As for generations, I am up to 9 with an Ale yeast and 2 on my Lager yeast, and have gotten comparable results to buying fresh yeast.

 

[Dland]

One comment I have is are you measuring how much of the yeast cake you repitch into each new batch? It sounded like you do, since you draw off the trub with the value at the bottom of your canonical, but wasn't explicitly stated how much you repitch. I typically save more than 32 oz of yeast cake after a batch, but only need 8 oz of Ale slurry / 16 oz of Lager slurry to repitch for a new standard strength batch. I have a friend who just pours wort on top of the yeast cake without any harvesting or measuring slurry first and he seems to get good results, but I would imagine that is way over-pitching and you could miss out on desirable esters. My friend's beers tend to be very hoppy IPA styles where you don't miss the esters anyway, but I tend to brew maltier beers that would be hurt by over-pitching, so I pay attention to how much slurry I repitch. As for generations, I am up to 9 with an Ale yeast and 2 on my Lager yeast, and have gotten comparable results to buying fresh yeast.

My conicals hold about a quart between rack and dump ports. Fermentor remains sealed, so that is volume of slurry. As you noted, I do try to get the solids out between batches, and let final trub dump run pretty "clear".

I've been making lagers w S-189 right now, and have been quite happy with flavor results. Beers have varied from pilsners, CAPs, to marzen, and I've not noticed any difference in flavor between this method and newly pitched yeast. The fermentation does get going faster though.

I've done up to 8 w lager and 3 w ale yeasts. Been a little nervous running ales too long between sanitizing conical, as it seems more bad things can get going quicker at the higher temps, but if you've done 9 w ale, that inspires me to be more bold.

 

[odie]

I only did it one time. I dumped fresh wort into a freshly racked bucket fermenter. All the previous trub was left inside. then did it again. So a virgin batch with 2 re-uses and no cleaning or trub removal. FWIW my wort is highly screened from the kettle so trub in the fermenter is minimal, the cake is assumed to be mostly yeast.

Both "extra" beers came out fine. all three were different lagers (Vienna, spiced winter, doppelbock)

 

[CascadesBrewer]

Dr Hans made a video where he reuse the same fermenter for a year.

As I recall, Hans would dump trub (and yeast?) out of the bottom each time so he was not reusing the entire yeast cake each time.

I missed the original discussion, but it sounds like the OP reused the entire yeast cake each time. Interesting!

 

[odie]

if he was using a conical that would be the way to do it...IMO

dump the trub early in fermentation... let the yeast fall... rack the beer... add fresh wort...repeat

 

[Dland]

The conical makes it a lot easier. I usually do a trub dump when I want to check gravity, so what often happens is I dump the solids and get a hydrometer reading, and if it needs to go another day or two I let it run some more, but if ready to rack, I rack right away.

Usually I try to dump & get reading before primary is finished, since I spund and D rest in kegs.

 

[bwible]

Both "extra" beers came out fine. all three were different lagers (Vienna, spiced winter, doppelbock)

I like to try to re-use my yeast at least a couple times, especially since I’m only brewing 3 gallons at a shot so it makes sense from a cost perspective. I pay about $10 for a liquid yeast shipped with an ice pack.

Yeast can be re-used but one thing I take into consideration is recipe selection and the influence of any remnants from the last batch on the next batch I’m about to brew. I don’t pull the yeast or wash it. I try to pour out a little of the trub and just pitch the next beer on top of the yeast cake from the last batch.

So it makes sense to me when planning to re-use yeast to brew from light to dark, weak to strong - same way judges judge beer. Does it make sense to brew an Imperial Stout then pitch a blonde ale on top of that yeast cake? No. I make my 3 or 4 beers with the yeast and then stop after either a very strong beer or a very dark beer. Any spiced beer would also be a stopping point since I wouldn’t want to carry the spices into the next batch.

Yeast could be split into multiple starters - I have done that just using beer bottles and airlocks. In theory you could get many batches out of one yeast.

Also depends on what you want to brew and what the yeast is good for. 1056 can make a whole bunch of styles. I have yet to figure out even a second style I can make with 3068 Weihenstephan Wheat yeast after making Hefeweizen. I’m not a big fan of cloudy, hazy, sour, or Belgian beers. Then if you settle on 1056 or 1272 there are beers those can’t make, like if you want to a proper Bitter or English Pale Ale. Then you need a different yeast and it starts all over...

 

[Gusso]

I only did it one time. I dumped fresh wort into a freshly racked bucket fermenter. All the previous trub was left inside. then did it again. So a virgin batch with 2 re-uses and no cleaning or trub removal. FWIW my wort is highly screened from the kettle so trub in the fermenter is minimal, the cake is assumed to be mostly yeast.

Both "extra" beers came out fine. all three were different lagers (Vienna, spiced winter, doppelbock)

I recently did the same. All 3 lagers came out fine.

 

[odie]

So it makes sense to me when planning to re-use yeast to brew from light to dark, weak to strong - same way judges judge beer. Does it make sense to brew an Imperial Stout then pitch a blonde ale on top of that yeast cake? No.

I've done stronger and darker to lighter and weaker with no issues....but I keep it within "family" so to speak...if both recipes call for the same yeast.

I always decant all the old beer off my yeast before pitching new wort. You only need a portion of the old yeast.

But yes, a stout to a blonde is a no-no.

 

[kpsalerno]

In the course of using the same S-04 yeast 10 times now, I have actually brewed stouts and then repitched yeast cake to an english bitter and even a hefeweizen, which came out great, and then to a pale ale. All were great and had no influence from each other, but again I only use 1 Cup of slurry per 5.5 gallon standard strength batches. The hefeweizen batch showed me how important it was to have properly milled wheat malt and use the right step mash schedule and even the influence of strike water ratio to make a very convincing hefeweizen everyone enjoyed without the use of a specialized strain, but by the right process and well controlled and thorough fermentation. With my lager slurry repitching, I tend to only brew munich helles and munich dunkel and sometimes a german style pils, all very similar-ish grists anyway.

 

[madscientist451]

I'm going to try it, ferment in a keg, only open it to dump in more wort, and see how many I can go

 

[Dland]

Had a good run with the late Feb pitch of S-189. Came to an end this weekend after eleven successful batches of lager.

Made a stronger than usual wort yesterday, 1.066, and the fermentor had been empty of beer for a week (except for a quart w least cake). The new wort did not get going after 20 hours, so I pitched some new yeast in to get it going.

Normally active fermentation has been apparent within 4 or 5 hours of adding new wort, and never not bubbling by next day. A factor in old yeast's apparent demise is my glycol set up is challenged to keep fermentor cool when not full of wort, and cellar has warmed to mid 60'sF, even though I tried to keep fermentor at around 54F, I know it got warmer when empty.

Time to go to ale for a few months anyway, so chiller does not have to work so hard, have 12 kegs of lager in line, will last the summer. I will be sanitizing fermentor next batch, and see if I can go until I switch back to making lagers when it cools off.