Pressurized Closed Loop Corny Keg Fermenting

[vtipsy]

What do you guys think about this idea for dryhopping:
Use a floating dip tube in the fermenting keg, and suspend a mesh bag containing a few oz. of hop pellets up in the corny lid, as high as possible. Use a release mechanism, maybe something magnetic, or rigged for a quick tug on the PRV, to drop the bag full of hops into the almost-finished beer, prior to transfer, and without opening the keg. Think it would work? Would it make a difference?
I suppose the same idea could be applied to the serving keg - rig them up in there and let them get flushed with CO2 from the fermenting vessel, keep things closed up, and then drop them in after transfer, without opening the keg.

I've thought about something like this. The idea is to keep the dry hops away from the yeast right? If you are spunding then there will be some yeast at the bottom of the serving keg. You could have your mechanism dangle the hops, keeping them away from the yeast but that would interfere with a floating dip tube.

 

[Veets]

I've thought about something like this. The idea is to keep the dry hops away from the yeast right? If you are spunding then there will be some yeast at the bottom of the serving keg. You could have your mechanism dangle the hops, keeping them away from the yeast but that would interfere with a floating dip tube.

Actually, the idea is to keep the aroma from the dry hop charge from being vented out during fermentation. Thus, drop them in late in the fermentation. Ideally, when you stop venting out and any generated CO2 is being used for carbonating the beer up to pressure.

 

[vtipsy]

Actually, the idea is to keep the aroma from the dry hop charge from being vented out during fermentation. Thus, drop them in late in the fermentation. Ideally, when you stop venting out and any generated CO2 is being used for carbonating the beer up to pressure.

So this happens if you time your transfer to the SV well while spunding. Ideally the remaining extract is exactly the amount required to carbonate the beer and nothing more. In practice that doesn't happen but it wont be a massive amount of hop laden C02 being vented either.

I'm not dismissing the idea, maybe that small amount of C02 does have a tangible impact. I'm also interested in dry hopping without the presence of yeast.

 

[schematix]

I’m a huge fan of spunded IPAs. The hops hang on for months longer than traditional methods.

BUT I am sick of the juicy flavors you get from dry hopping during active fermentation. Can’t get pine or dank to come through.

I’m thinking a recirculating dry hop for even a few hours during spunding might do it.

 

[hezagenius]

I’m a huge fan of spunded IPAs. The hops hang on for months longer than traditional methods.

BUT I am sick of the juicy flavors you get from dry hopping during active fermentation. Can’t get pine or dank to come through.

I’m thinking a recirculating dry hop for even a few hours during spunding might do it.

What hop types and what is your timing in the kettle and dry hop?

 

[schematix]

My house IPA is usually about 2lb for 10 gallons.

Usually something like 4/2/2/4/5/5/10 60/20/10/5/170F/140F/Dry

Last round I did 8oz each of centennial, azacca, chinook and el dorado. It’s not as juicy as citra/mosaic/simcoe.

Definitely get grapefruit prominently. Not much orange. A little lemon. No pine or dank though.

 

[hezagenius]

I've had good luck with Apollo and Strata for getting dank flavors. If you throw Apollo in the boil or flameout, it gives off quite a dank aroma. I usually add Apollo and/or Strata in my whirlpool after I've cooled the wort off a bit, maybe to 140F.

I made a Swish clone with Citra, Mosaic, Simcoe and Apollo and one comment I got was that it tasted like liquid MJ. The hop bill for that was:
5gal, 22oz of hops
FWH 0.5 Apollo
Flameout 1.0 Mosaic
180F 4.0 Citra, 4.0 Mosaic, 1.0 Simcoe for 60min whirlpool
Day 2 2.0 Citra
Day 3 1.0 Apollo, 1.5 Mosaic, 1.0 Simcoe
Day 6 2.5 Citra, 2.5 Mosaic, 1.0 Simcoe

Another beer I did that was fruity and dank was:
5gal, 14.75oz of hops
60min 0.75 Columbus
180F 3.0 Strata for 30 min
165F 3.0 Strata for 30 min
Day 3 2.0 Citra
Day 6 6.0 Citra

 

[vtipsy]

I’m a huge fan of spunded IPAs. The hops hang on for months longer than traditional methods.

BUT I am sick of the juicy flavors you get from dry hopping during active fermentation. Can’t get pine or dank to come through.

I’m thinking a recirculating dry hop for even a few hours during spunding might do it.

Interested to see how that works out. How would you go about recirculating, a peristaltic pump? I've used and abused the NEIPAs for a while and now I'm getting cravings for dry PNW style IPAs.

 

[Hannabrew]

I "recirculate" my keg hops during spunding by swirling the keg often and aggressively

 

[vtipsy]

I "recirculate" my keg hops during spunding by swirling the keg often and aggressively

Nice.

 

[hezagenius]

I "recirculate" my keg hops during spunding by swirling the keg often and aggressively

Same. If you don't, you just end up with a hop sludge floating on the surface. I give mine a good swirl at least twice a day while dry hopping. I've often wondered if you could do some sort of large stir plate with a fermenter. Nothing crazy, just enough to get the hops moving around.

 

[schematix]

yah nice try but that doesn't count

Yes i'm thinking peristaltic pump would be best to reduce the sheer forces

 

[Hannabrew]

I realize my manual method isn't as graceful and won't get as much extraction but it also doesn't introduce any Oxygen as I imagine any external pump would right?

 

[thekraken]

If you're dry hopping during active fermentation aren't you already getting agitation from the swirling of the fermentation itself?

 

[vtipsy]

If you're dry hopping during active fermentation aren't you already getting agitation from the swirling of the fermentation itself?

Maybe. If you are dry hopping while spunding there is going to be a lot less agitation than doing it at high krausen.

 

[vtipsy]

I swirled aggressively once and dislodged the floating dip tube. Pumps and stir bars are definitely on my radar. schematix, what tubing are you thinking for the peristaltic pump? You would want it to be less permeable than silicone and able to handle higher pressure.

 

[schematix]

Probably something like a thick walled or double walled pvc (beer line?). Definitely not silicone due to permeability.

Also one of the reasons i'm thinking to only recirc for a few hours is to limit exposure time. Obviously great care would need to be taken to purge the recirculation loop, hops, etc. I still think spunding is part of the solution too.

 

[thekraken]

What about a hopback? Push your beer to a serving keg with an inline home water filter full of hops in between them?

 

[vtipsy]

Probably something like a thick walled or double walled pvc (beer line?). Definitely not silicone due to permeability.

The pump works by positive displacement i.e. squeezing the tubing. So it needs to be very flexible.

 

[vtipsy]

What about a hopback? Push your beer to a serving keg with an inline home water filter full of hops in between them?

Transferring takes what, 30 mins? Is that enough time to extract from the hops?

 

[schematix]

The pump works by positive displacement i.e. squeezing the tubing. So it needs to be very flexible.

Yah i had the same realization on my drive home last night.... thick walled beer line definitely not the way to go.

Not a lot of time to dedicate currently but some other ideas could be a diaphram pump, or just use silicone (?) tubing and limit exposure time.

 

[stickyfinger]

The pump works by positive displacement i.e. squeezing the tubing. So it needs to be very flexible.

I'm sure McMaster Carr or Cole Parmer have the perfect tubing for the job, some soft, food grade peristaltic pump tubing that maybe would be decent at keeping out oxygen. Though, for the short contact time, I don't know how bad the oxygen exposure would really be. I mean, is oxygen really going to get through the tubing in a day, maybe. Anyway, where there is a wallet, there is a way.

 

[vtipsy]

This stuff is low my priorities too but I want to revisit at some point and get it nailed down.

 

[stickyfinger]

My first spunding setup was just delivered today, woo hoo. I have a couple questions about the process:

- once i remove the blowoff setup from the FV and reattach the gas out post and poppet, should i pressurize the FV with my CO2 cylinder to like 5 PSI and attach the spunding valve to it to ensure the oxygen that was introduced when i took off the blowoff setup is removed (before connecting the jumper to the SV?)

- how long should i wait to attach the SV to the FV and move the spunding valve over to the SV so that pure CO2 can purge the SV?

- when doing a dry hop, i would take off the jumper, add the dry hops to the FV, seal up the FV and then purge the head space with my CO2 cylinder a few times? Would I then move the spunding valve back over to the FV from the SV so that the oxygen introduced during dry hopping can escape or be consumed by yeast? How long do I have to wait for the oxygen to be consumed? Should I set the spunding valve to 20 PSI at that point or keep it low ( I assumed why not set it high at that point.)

- Once I am confident the oxygen introduced into the FV during dry hopping is purged or consumed, I assume I can then reattach the jumper (after purging it by using the pressure in the SV) b/w the FV and SK and let the pressures equilibrate. The 4-5 points of gravity is enough to both carbonate the beer and pressurize the SV to 20 PSI?

 

[chieftain]

It's not a silly question.

There is a fantastic post by doug293cz that wowed us with some maths, if you haven't seen it its here https://www.homebrewtalk.com/forum/threads/keg-purging-with-active-fermentation.628658/

Taking the same initial assumptions he did and adding further that
- You spund with 1 Plato of extract remaining.
- Head space after filling the spunding keg is 1 L of air (210000 ppm oxygen)

1 Plato is 1% sugar by weight. Thats 0.2016 kg of sugar, 0.1037 kg of C02 after its fermented. Thats 51.850 L or 518,500 little bubbles.

Plugging that into his final formula gives:
Final O2 Conc = 210000 ppm * ((1 L - 0.0001 L) / 1 L)^518500 = 6.352e-18 ppm

That's nothing.

You'll dissolve some oxygen as you transfer into the spunding keg and as Hannabrew just said it's really easy to purge with fermentation so that's what I do.

* I've had a few beers tonight so apologies if I made a mistake (do your own calculations - don't trust weirdos on the internet).

One question about purging with fermentation C02 - should I see the jar of sanitizer bubble up, like a normal airlock would? This is connected to the serving keg via a quick disconnect attached to the gas out post.

 

[stickyfinger]

One question about purging with fermentation C02 - should I see the jar of sanitizer bubble up, like a normal airlock would? This is connected to the serving keg via a quick disconnect attached to the gas out post.

i would think you have to use a spunding valve or there wont be enough pressure to seal the keg lids, but i might be wrong.

 

[degivens]

i would think you have to use a spunding valve or there wont be enough pressure to seal the keg lids, but i might be wrong.

It seals well enough and once fermentation begins it’s no problems what so ever.

 

[stickyfinger]

It seals well enough and once fermentation begins it’s no problems what so ever.

wow! really?! I had assumed you needed a little back pressure from the spunding valve to seal the kegs. I wonder what the pressure is in the kegs when the fermentation is going strong? I guess it depends on the diameter of the tubing you are using?

I HAVE noticed that my brand new kegs with good o-rings and no dents do hold pressure at pretty low PSI. I guess if this is true then you could probably do all of this without a spunding setup if you needed to. Also, if you filled up a large column of water or starsan for the output, you could increase the pressure in the kegs.

 

[schematix]

Brand new kegs seal really well. Wish I had never bought used ones. Not worth the hassle.

 

[degivens]

wow! really?! I had assumed you needed a little back pressure from the spunding valve to seal the kegs. I wonder what the pressure is in the kegs when the fermentation is going strong? I guess it depends on the diameter of the tubing you are using?

I HAVE noticed that my brand new kegs with good o-rings and no dents do hold pressure at pretty low PSI. I guess if this is true then you could probably do all of this without a spunding setup if you needed to. Also, if you filled up a large column of water or starsan for the output, you could increase the pressure in the kegs.

Not sure what the internal pressure is off the top of my head. Maybe i’ll math it out in the morning. Suffice to say it’s more than enough for a good seal and enough to prevent oxygen ingress.