Pressurized Closed Loop Corny Keg Fermenting

[Hannabrew]

i’ve been fermenting out my beer, adding 1 oz/gal dry hop along with about 50-60g of sucrose boiled in water, seal it up and purge and set lid to 20 psi. leave it for 1-2wks and then throw into keezer. seems to produce very hoppy beer

I'm leaning toward trying this on my current batch. The common thinking is get the ipas on tap fast but with no o2 exposure, time could actually work in your favor.

 

[chieftain]

While I can't say that I've noticed any negatives from capping/spunding near the very end of fermentation with any non-dryhopped beers, I'm starting to lean towards adding dry hops near the end of fermentation and then capping or spunding to naturally carbonate being a very bad thing for hop character in the finished beer. I've had 2 hoppy beers that I think I essentially ruined with this method already this year. In both beers, the hop aroma/flavor was totally lacking and had a weird harsh, maybe even chemical/soapy, characteristic to it (both beers used the same source RO water from the grocery store that I use for all my beers, before anyone goes shouting "chloramines!" or anything). It's hard to explain - you can smell and taste that there are hops in there, but its a different kind of flavor/aroma than anything I've ever had before. Kind of like if you removed all of the supporting characteristics from the hops (fruity, floral, pine, resin/dank, etc) and were just left with generic hop presence.

Each beer had some different ingredients and other tweaks going on so I wasn't sure where to place the blame (thought it was maybe some bad cryo hops, the Imperial Juice yeast, different base malt), but the one thing both batches had in common was that I added all the dry hops (over 1oz per gallon) as the fermentation was finishing up and then removed the blow-off and let to finish fermenting and naturally carbonate. With the first batch, I decided to blame the cryo hops, since it was my first time using them and they seemed to have a brown appearance and duller aroma in the package compared to the pellet hops I was using in the same batch. When it happened to me again this past weekend, I began to think maybe in my attempts to preserve and maintain the freshest/brightest hop character by sealing in all the goodness at the end of fermentation, my efforts might actually be having the opposite effect due to some weird yeast/hops/off-gasing/pressure interaction.

Doing some searches, I came across a blog post on Scott Janish's site seemingly dealing with the topic I was looking into. While the experiment in the main post doesn't sound like exactly the same scenario (his "experiement" used different yeasts, dry hop schedules for the different batches and fermented one under pressure for the full fermentation), but some of his comments in the discussion below seem to deal with exactly what I had done with my 2 failed beers - regular fermentation for the first 90%, then tossing in dry hops at the end and then allowing to naturally carbonate. To my surprise, it sounds as though he made the same/similar observations with multiple batches whenever attempting this.

Below is the link to the post and some of his comments:

http://scottjanish.com/fermenting-dry-hopping-pressure/

"I’ve tried spunding on the tail end of fermentation a few more times and I’d suggest against it actually. I’ve never been thrilled with my results, I always seem to get a milder flavored beer from it."

"I’ve done a few beers where I cap the fermentation towards the tail end of fermentation with the last dose of dry hops essentially allowing the beer to naturally carbonate. Each time I’ve tried this, however, I wasn’t thrilled with the result. Thinking I would trap in more of the hop aromatics (not being vented with C02 under pressure) and increase aroma, I actually seemed to get the opposite, a more muted hop character with a “green” note. I’m not sure if I’m also trapping in some of the undesirable components of fermentation or what, but experimenting with this method a few times and getting the same result, I’m leaning against the processes. "

I may try doing a real side-by-side experiment in the future to compare to, but seeing as though the beers that the 2 times I've tried this have resulted in drain-pour beers (although hoping I may be able to salvage something out of my latest with some additional dry hopping), I'm not in a huge rush to do this knowing that half the beer is likely going down the drain. I'm not sure "muted" or "milder" quite does it justice - there is something just totally off about the hop character in these. NEIPA beers that I have added dry hops on day 2 and still have another 1-2 days before I cap or spund to pressure haven't had this issue. Neither have ones with all hops at the very end of fermentation but no spunding.

Anyways, sorry for the long post - what experience do y'all have with this? Anyone having good results with this method? Or similar bad results? Or ideas on good ways to dry hop late or after fermentation while limiting O2 exposure?

I've had good results transferring from my fermenter to a purged serving keg with loose dry hops, with anywhere from 10-15 points remaining (timing mostly driven by my schedule). I let it finish fermenting at low pressure (3-5 PSI) over a day or so, and then let it run up into 20+ PSI to get mostly carbonated.

Latest beer is primarily Mosaic dry hop, and it's got a great berry/citrusy aroma.

 

[DaveGillespie]

I haven't dry hopped under pressure yet, so it would be cool if some of you folks who are doing so already and getting results they are happy with could outline their schedule eg. What pressures, for how long, when you are adding your dry hops, whether the whole fermentation is under pressure or just spunding, etc

 

[crane]

I haven't dry hopped under pressure yet, so it would be cool if some of you folks who are doing so already and getting results they are happy with could outline their schedule eg. What pressures, for how long, when you are adding your dry hops, whether the whole fermentation is under pressure or just spunding, etc

I have used 2 different dry hopping schedules both with great results at getting hop flavor and aromas into the beer. However, the hops will fade over time faster with the first method, which may not be a problem if you can consume it all in ~4 weeks. I can attest that the second method has worked tremendously for preserving hop flavors and aromas. The last beer I brewed was a NEIPA in April this year. Long story short I had a few surgeries this summer and didn't drink much of that keg until recently. I just had the last glass this weekend and it amazed me how much aroma and flavor was still there after 5 months of lagering.

Older west coast IPA method: ferment under pressure to terminal gravity starting at 5-10 psi. Place dry hops in second keg and purge with CO2. Counter pressure transfer into dry hopping keg and sit for 3-7 days depending on my laziness. I have served directly from the dry hopping keg or I have transferred to another purged keg to get them off the hops.

Newer NEIPA method: ferment under pressure but only up to 2-3 psi for the first 36-48 hours. Then I bleed off the excess pressure open the top and add the dry hops. Seal it back up and crank the spunding valve up to 10 psi. Let fermentation complete then cold crash before transferring to a water purge keg.

 

[DaveGillespie]

In your first method, was the keg CO2 purged from being filled with air? Did you ever try this with a water purged keg?

 

[Andre3000]

I haven't dry hopped under pressure yet, so it would be cool if some of you folks who are doing so already and getting results they are happy with could outline their schedule eg. What pressures, for how long, when you are adding your dry hops, whether the whole fermentation is under pressure or just spunding, etc

Honestly, to avoid having to open the fermentation keg I've been throwing all my DH hops in right at yeast pitch. The less mucking about I've got to do the better IMHO. Not sure if this is ideal or not but it's been working for me. I've got an NEIPA-like beer in the kegerator that's over two months old and it still has all kinds of aroma.

I usually start spunding at day 5 or so. Sometimes this is too late. Day 4 is better.

 

[DaveGillespie]

Any thoughts on dry hopping forWest Coast style beers?

Also, RE: the discussion up thread about Hefes. Currently drinking one with a 45/55/63/71/78 mash schedule (temps in Celsius) then fermented with 3068 and kegged on day 5 with an additional 30g sucrose - spund at 20psi. No off flavours, total clove bomb. I do recognise the unwanted sulfur a Hefe yeast will throw off and have had it hang around in a fermenter for 2 weeks plus, but it's not in this beer.

 

[stickyfinger]

Honestly, to avoid having to open the fermentation keg I've been throwing all my DH hops in right at yeast pitch. The less mucking about I've got to do the better IMHO. Not sure if this is ideal or not but it's been working for me. I've got an NEIPA-like beer in the kegerator that's over two months old and it still has all kinds of aroma.

I usually start spunding at day 5 or so. Sometimes this is too late. Day 4 is better.

how many oz and how full is the keg? the online concern i would have is clogging something if too full with dry hops in there at high krausen

 

[crane]

In your first method, was the keg CO2 purged from being filled with air? Did you ever try this with a water purged keg?

Not sure how you can water purge a keg with hops in it, so yes it was just purged with CO2, not water followed by CO2.

 

[Andre3000]

how many oz and how full is the keg? the online concern i would have is clogging something if too full with dry hops in there at high krausen

I'd have to look back at my notes but 5 oz-ish? This is a 4.5 gal batch in the 5.1 gal keg or whatever it is. I usually get minimal or no blow off from this. The Clear Draught floating dip tube with screen has worked wonders for me. Never had an issue transferring.

My biggest complaint is sometimes it leaves a bit too much beer in the bottom for my liking. But I realized something the other day; this is most likely because the beer is foaming up towards the end of the transfer. And the reason why is I use the serving keg to purge lines, this causes the entire system to be slightly under pressured, allowing the beer to foam up slightly by the time the transfer is almost finished. Next time I'm going try transferring under higher pressure than spund, and see how that affects the foaming of the last bit.

 

[Baldilocks_Brewing]

I ferment in corny kegs - always do split batches of 7gal - 3.5gal into each keg.
Day 0 - fermenting keg, water purged and wort added.
Day 0 - serving keg, water purged then dryhop added (keg hops) - hold for now
12-24hrs - gas "in" from fermenting keg to "out" of serving keg with dryhops. "In" of serving keg to sanitzer so that ferment gas flows thru bith an escapes. This CO2 purging continued until about 60-72hrs post pitch.
60-72hrs - biotrans dryhop added to fermenting keg. Gas out removed from serving keg to allow pressure to build in both fermenting & serving kegs. Spund to 22lbs. Separate & seal serving keg.
Day 10 cold crash fermenting keg for two days.
Day 12 transfer to serving keg for the final dryhop (serving keg still pressurized) beer naturally carbed from spund.
Day 14 chill, gas and serve

 

[DaveGillespie]

When I refer to adding dry hops to a water purged keg I think of what is described above ie. Water purge keg, depressurize, add dry hops, re pressurize. As opposed to simply "purging" in the initial step without water.

 

[crane]

What's the point of water purging if you open the lid and let oxygen in with your dry hops? There is no possible way to add hops without adding oxygen.

 

[cheesebach]

What's the point of water purging if you open the lid and let oxygen in with your dry hops? There is no possible way to add hops without adding oxygen.

If you can feed in CO2 at a low pressure (say around 3psi) to a fully water-purged keg while quickly opening the lid, adding dry hops, and resealing, I’d be willing to wager that the O2 concentration in the keg at the end of the process is better than you’d get by 20 cycles of a purge-release type purging, while using less CO2 in the process.

 

[Baldilocks_Brewing]

By water purging first you get 99% CO2 in serving vessel. Removing the lid to add dryhop WILL introduce atmospheric O2 BUT it will mix with the CO2 at a rate slow enough that the O2 concentration in keg is still lower than in atmosphere - therefore minimizing oxidation of dryhops waiting in keg (pelletized hops are not so fragile that will ruin from oxidation in a matter of hours). Approx 12 hrs later a steady stream of 100% pure CO2 will be introduced to said keg. This offgassing from fermentation will provide enough CO2 to mix in serving keg to drive up the concentration back to 99%+ (offgassing is enough to purge five kegs).


As a side note - I have tried the single large dryhop at biotransformation (6 batches), spund and serve in same fermentation keg to try to get the true benefit of closed loop / no O2 induction. I did not like the result. Flavor was definitely there but the aroma was substantially lacking versus a double dryhop (assume yeast stripped it out). I incorporated the double dryhop I outlined previously (crash before final dryhop - see Monkish brewing podcast) with closed loop fermentation and the results are outstanding. When pouring from tap aroma can be smelled 6foot away. Flavor is amazing too. Longest keg I have had is two months before empty - no appreciable differences in flavor/aroma at the end.

I use 8lbs/bbl hops. 5% hops in boil, 25% hops whirlpool, 35% biotrans hop, 35% dryhop #2

 

[Andre3000]

If you can feed in CO2 at a low pressure (say around 3psi) to a fully water-purged keg while quickly opening the lid, adding dry hops, and resealing, I’d be willing to wager that the O2 concentration in the keg at the end of the process is better than you’d get by 20 cycles of a purge-release type purging, while using less CO2 in the process.

This is kind of what I do but with an extra step if I have to open the keg:

-Hook a purged CO2 keg or or if you're not overly anal about commercial CO2, the cylinder up to the gas post on the keg you wish to dry hop into.
-Quickly add dry hops and put the lid in but leaving it a tiny bit cracked open slightly off alignment.
-If you're using a CO2 keg you have to have a valve inline on your jumper hose to meter the flow rate!! Connect CO2 keg or cylinder and turn gas on at a reasonably low flow rate and allow it bleed in through the gas port, into the head space and out through the cracked lid.
-After 10 seconds or so, with the gas still flowing, move the lid into position and it should seal up instantly.

I believe with this method there is sufficient agitation of the head space with the CO2 flowing that there should be little to no O2 in the keg after you seal it up. I agree with you in thinking that purging via displacement is far superior rather than the pressurize and release method. And I agree with you, this is better than pressure purges in many ways.

I use 8lbs/bbl hops. 5% hops in boil, 25% hops whirlpool, 35% biotrans hop, 35% dryhop #2

I liked the looks of these ratios. I might have to give this a go.

 

[Baldilocks_Brewing]

Well sh*t, turns out I have a yeast allergy... (Gas, bloating, loose stool, etc)

In spite of that I still plan on brewing my faves - Hazy IPAs & Pilsners. I have been reading all of the relative posts on here from folks that have similar issues. It looks like the best option is a plate filter. Question for all you oxidation gurus - any suggestions to minimize O2 exposure in the closed loop corny transfer with a plate filter?

 

[stickyfinger]

Well sh*t, turns out I have a yeast allergy... (Gas, bloating, loose stool, etc)

In spite of that I still plan on brewing my faves - Hazy IPAs & Pilsners. I have been reading all of the relative posts on here from folks that have similar issues. It looks like the best option is a plate filter. Question for all you oxidation gurus - any suggestions to minimize O2 exposure in the closed loop corny transfer with a plate filter?

Do you think you could try cold crashing and using gelatin finings as a first step? I think that is advisable before using a plate filter anyway if you need to go that route to prevent clogging the filter prematurely.

 

[ttuato]

Do you think you could try cold crashing and using gelatin finings as a first step? I think that is advisable before using a plate filter anyway if you need to go that route to prevent clogging the filter prematurely.

I do cold crash before transfer. I haven't tried fining though. I will give that a shot on the next batch.

 

[leesmith]

Do any of you guys know how long it takes to purge a serving keg with fermentation gas from the fermenting vessel?

Water purged vs. just hooking it up without doing any “pre” purge?

 

[Hannabrew]

A normal 1.050 or so fermentation can purge a couple of kegs based on the math I've seen so I would guess about half you high krausen time would be sufficient.

 

[Andre3000]

Do any of you guys know how long it takes to purge a serving keg with fermentation gas from the fermenting vessel?

Water purged vs. just hooking it up without doing any “pre” purge?

I've found the water purge too time consuming and arduous. What I do now is sanitize the serving keg, purge the sanitizer through the picnic tap, then let the CO2 run for a bit through the keg and out the picnic tap. Between that and fermentation, I'd be surprised if there's any O2 left in it by the time it's done.

 

[leesmith]

Do any of you guys know how long it takes to purge a serving keg with fermentation gas from the fermenting vessel?

Water purged vs. just hooking it up without doing any “pre” purge?

I guess what I'm getting at is if it takes an hour of full on high krausen co2 production to clear out an already co2 tank purged SV keg to zero o2 then I'd might try to put some hops in the SV, purge by co2 tank, and then FV purge the last remaining bit of o2 with a spunding valve to hold some pressure. Then disconnect the pressurized SV and keep it chilled during the remainder of the FV primary; to keep the hops fresh. Then reconnect at the end of fermentation to close transfer onto the 2nd dry hopping that's in the SV. Priming the FV before transfer.

IF it takes a long time (hours or days) to clear the SV of all o2 then I wouldn't want to leave the hops in the SV for fear of heat destroying the aroma and flavor of the hops.

 

[schematix]

I’ve dropped water purging in favor of fermentation gas purging. Much easier.

I use all the fermentation gas once fermentation has started. I wait until it starts so I’m not pushing the oxygen rich head space of the freshly oxygenated fermenter through the kegs.

It does require you use all the fermentation gas though. Someone ran the numbers and a simple purging with tank co2 will be ineffective unless you waste a crap ton of tank gas.

 

[leesmith]

I’ve dropped water purging in favor of fermentation gas purging. Much easier.

I use all the fermentation gas once fermentation has started. I wait until it starts so I’m not pushing the oxygen rich head space of the freshly oxygenated fermenter through the kegs.

It does require you use all the fermentation gas though. Someone ran the numbers and a simple purging with tank co2 will be ineffective unless you waste a crap ton of tank gas.

But do you think it’s possible that an already co2 tank purged keg could give up the ghost (100% o2 purge) in a short period of time if connected to a FV?

 

[Andre3000]

Someone ran the numbers and a simple purging with tank co2 will be ineffective unless you waste a crap ton of tank gas.

Do you remember the post? I'd like to see those numbers. The pressure up and release is very ineffective but that's not the method I'm talking about here, which is hooking the gas up and having it flow out an open picnic tap via the beverage post dip tube at atmospheric pressure. In a perfect world, all you'd need is one keg volume of CO2 displaced through but obviously there is no way to ensure that all the CO2 you're putting in is 100% displacing O2, there is a lot of mixing happening.

 

[leesmith]

How do you calculate how much sugar to add to a pressure fermented beer. My beer finished at 16psi after adding dry hops and is at 1.010 and ready to prime before transferring. Do I do the full amount of sugar or half? OR some other measurement?

 

[leesmith]

How do you calculate how much sugar to add to a pressure fermented beer. My beer finished at 16psi after adding dry hops and is at 1.010 and ready to prime before transferring. Do I do the full amount of sugar or half? OR some other measurement?

Went for it with the full amount of priming solution. Figure I’ll just spund to relieve excessive pressure.

Used hannabrew’s injection method...screwed it up a little but I’ll get it on the next go around. Worked great.

 

[enormous13]

Went for it with the full amount of priming solution. Figure I’ll just spund to relieve excessive pressure.

Used hannabrew’s injection method...screwed it up a little but I’ll get it on the next go around. Worked great.

View attachment 594722

For those of us not familiar, what is hannabrew's injection method?

 

[leesmith]

For those of us not familiar, what is hannabrew's injection method?

Pressurized Closed Loop Corny Keg Fermenting
https://www.homebrewtalk.com/forum/index.php?posts/8278917/

The post above.