Recirculating active fermentation... has anybody done it?

[davidgsmit]

Gents (and ladies),

I recently spoke to a brewer concerning the process behind making one of my favorite barley wines and he brought up something that seems to be a bit of a foreign concept to home brewers;

He mentioned that it took a lot of work to get to the final gravity (13.5% abv) and to do so they "recirculated active fermentation" for a number of days while adding measured amounts of both oxygen and nutrient charges.

I'm assuming he literally means pumping the wort while the yeast is in the active fermentation stage to keep it suspended, thus increasing its effectiveness especially while adding more oxygen and nutrients. Does anybody here have experience doing this?

I'm guessing many here would say "YOU CAN'T DO THAT!" without ever having tried it, so I'm looking for some evidence that this does indeed work and serves a meaningful purpose with regards to attenuating big beers sufficiently.

Any feedback is appreciated! Especially with regards to how it's done! I'd hate to reinvent the wheel on this if it's been done successfully on a small scale before. I did a number of searches on the web for this, but so far I've only come up with articles on Burton Unions (which I now must try as well!).

Thanks!

 

[Brulosopher]

My main concern would be oxidation... interesting.

 

[davidgsmit]

And that's exactly what I was expecting to hear!
But if you consider that the purpose of this is to add enough oxygen to feed the yeast, but not too much to oxidize it it makes sense. I know the magic number is 8ppm, but how you figure out how much oxygen you can add and at what interval without overdoing it, that I would love to have somebody lay out in more detail, especially for a 5-6 gal batch.

I was told that oxygen was added every six hours (automated I would assume) which raises another question; can this be automated in a rather cost effective and precise manner for the home brewer?

Looking forward to this thread...

 

[ChillWill]

No idea how you'd do it on a homebrew scale but commercially you can get conical fermenters with agitators in them that keep things moving, then hit it with oxygen and measure how much on an oxygen meter.

As long as you've still got a bit of fermentation to go the yeast will deal with oxygen.

 

[TarheelBrew13]

This sounds like what Sam Smith does when they "rouse" the yeast. I'd check their site for info.

 

[Phunhog]

I think it could be done but if you are only dealing with a 5 gallon carboy why not just shake it up? It would keep the yeast in suspension which is what you need. As far as O2 levels...you would need a meter....anything else would just be a guess.

 

[davidgsmit]

Indeed I would definitely use an oxygen meter to apply an extra burst every so many hours.

I'm thinking an occasional shake of the carboy wouldn't be enough, but I'll have to look into this and will probably try it in the near future to see how quick things settle again.

So the key question here is: Does anybody know how to calculate how much oxygen would be needed to create optimal fermentation without oxidizing the beer? Seems there's a way to do it as some people ARE doing it.

One other consideration... how about an over sized stir plate to keep things moving? Seems like that would be the obvious solution to the recirculation issue in a carboy.

Off to brew a pale ale! Cheers!

 

[OvaTersley]

B.A.S.P. (Big Ass Stir Plate)

I've always been led to believe that any oxygen during active fermentation is a bad thing. Is this a misnomer?

 

[Phunhog]

During fermentation, especially for a big beer, the yeast need the oxygen. I have heard of brewers adding O2 during fermentation, especially the first 24 hours. The problem arises when you have no way of measuring how much O2 is in the wort to begin with. I would play it safe and not add O2 during active fermentation unless you had a dissolved O2 meter.

 

[ChillWill]

Here's some food for thought:

- you can over do the oxygen and get too much yeast growth (crabtree effect iirc)

- doing it after first 24 hours may not be used up and increase staling (oxidation takes a while, but the more oxygenated your beer, the more it'll oxidate)

- a lot of aromatics are pretty volatile, the more you agitate, the more you'll lose

 

[davidgsmit]

Well, in that case I'm going to ask the original brewer how big their batch was. I know how much oxygen was added and at what intervals, so I'll just scale it down to size. I'll probably do a tad bit less just to be safe.

With regards to yeast circulation, I've decided to build the following:
https://www.homebrewtalk.com/f51/mega-stir-plate-w-pic-144360/

Go big or go home right?

 

[Patirck]

Without a dissolved o2 meter, I think adding oxygen after fermentation has started is a shot in the dark - you could easily over do it. On a homebrew scale of things, If you want to rouse the yeast without adding o2, I think the safest way is to use a sanitized stainless mash paddle or spoon and very gently lift the cake off the bottom of the carboy. Try not to stir as you may get a small whirlpool which can end up adding air to the beer when you don't want to.

 

[Brewindruid]

Sorry for the bump on an old topic, but this subject peaks my curiosity.
Fist off, please correct any of my misconceptions with regards to the following:
Open fermentation has a long, and succesful history, so passive oxidation musdt not be a real issue during active fermentation.
Yeast adapt to the job at hand and only pick up O2 during growth phase, so additions after 15 to 20 hours is probably pointless.
I have read of British brewers doing what is called a step down, which would be akin to us simply re-racking after 24 hours. I would assume this gets rid of more transfer material as well as yeast that has quit or didn't grow.
In the yorkshire square system yeast is either sprayed up or the climbs up onto flats and then falls back into fermetation, but this seems somewhat pointless as healthy yeast swim and move abot quite well.
I don't know, I am certainly no expert, and am very quilty of wanting to over engineer ever bit of this process.
I might just re-rack after growth phase and re add blow-off as Krausen, by saving it in a closed sterile system.
Definitely makes for a good experiment.

Thouts?

 

[Brewsday]

Let me preface this comment with the fact that I just stumbled onto this thread looking for something completely different but got interested...oh, and this is way above my head but I commend your willingness to "set aside" conventional wisdom and I look forward to reading from others more knowledgeable...

I like the captured krausen concept. I've read that's a way to harvest yeast too, since top fermentation blow offs have a lot of yeast in them.
One guy mentioned shaking the carboy...It would seem to me once you've reached even a modest stage of fermentation most O2 in the head space will have been driven out.

How about holding some wort aside, then oxygenate (and add your krausen?) and then add it a day or two later? (perhaps even pull it off at the end of the boil into a no-chill vessel). Seems like that might bump the process up again. I do have a little experience with no-chill and it created some excellent brown ale and a very smooth APA where I put hops in the chilling vessel just before the boiling wort hit it).

A few experiment cycles and you might find the right, easy-for-a-homebrewer, very controllable formula. Good luck, please keep posting, I'll stay subscribed.

 

[Brewindruid]

Doh!!!!!
Sincerest apologies for the spelling errors. My eyes are horrible and I didn't even notice the obvious mistakes.
In reflecting on some of these methods, I have come to the conclusion that they are, perhaps, more lent to the commercial level of volume, and that, at our scale, they would prove to be more work for very little return.
I am going to do either a pitch to the kettle and rack after 24 hours or rack from carboy to carboy after 24.
I also might save some starter wort to add to the blow off container. Here my concern is infection more than anything else.I would tend to think that if the starter wort is chilled and saved there should be no issue, but I think the active ferment should be enough to overwhelm most anything.

 

[davidgsmit]

After further consideration I've decided it's probably not all that difficult to add oxygen in a controlled manner on a small scale. Here's how I've come to this conclusion;

Wife and I brewed a quad recently that puttered out far too early. We ended at around 1.032 if memory serves me right, but were shooting for about 1.012 (I think). To fix this we had to rekindle the yeast. We ended up racking to secondary, harvesting some of the yeast, then made a starter with more DME than is typical for a starter to get the yeast acclimated to the higher alcohol content of the beer we were pitching into. The obvious question loomed however: how to we add enough oxygen to get the beer down to our target gravity without oxidizing $70 worth of beer (10 gal batch).
We ended up pulling off a gallon of the beer... I then shook the hell out of that gallon (aerating via the shake method caps out at 8ppm and pretty quick too, or so Wyeast has found by testing the different methods). Then I poured in the decanted yeast starter, then added it all back in with the rest of the beer. The beer ended up at 1.017 which is't bad for an educated guess! Based on the sample I tried I did not notice any oxidation.

All that said, if we know that the shake method caps out at 8ppm and it takes less than a min of shaking to get there (per Wyeast at least) then we should have a fairly good sense of how to add a targeted amount of oxygen to our beer.

If I need an estimated 12ppm for a larger beer (just throwing a number out there that's probably fairly accurate) but can only attain 8ppm by shaking, then I should theoretically be ok if wait for let's say 8 hours to go by, then pull off half of my batch and shake it up again and add it back in. I highly doubt you'd risk on oxygenated beer using that logic as long as you did this within the right time frame. I suppose the argument against this is that you don't really know where your yeast is at unless you've got your pitching down to a science and tend to always use the same/similar yeast. Perhaps waiting for the very first sign of active fermentation would be the best way of discerning this? (airlock activity, wort moving around, hint of bubbles/foam)

Apparently there's a need for additional oxygen with beers that approach the 15% range even if one has an oxygen tank and stone. Why else would the brewer bother if they could add enough up front? I would suspect this may have to do with oxygen coming out of suspension before the yeast can fully utilize it, but really don't know for sure.

I'm sure there's a lot of opinions on this. Personally I feel this isn't too risky of a method at all unless I'm missing something... Thoughts anybody?