Author Topic: Dry hopping during active fermentation  (Read 12625 times)

Offline narvin

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Re: Dry hopping during active fermentation
« Reply #15 on: April 25, 2016, 08:42:32 pm »
Bubbling CO2 through beer is a well known technique that can scrub aroma and flavors, so why not hops?  It may not reduce IBU but I'd bet it can remove some volatile compounds from dry hopping.  If your fermentation is almost done, it may not remove much in practice.
Good point. The question is how much it would actually remove in practice. I have an old keg of IPA I've been meaning to dump to make room for some new batches. Maybe I'll throw a couple of ounces of hops in the keg for a few days then go through some purge/degas cycles to see what happens. It's probably more extreme than what would happen during fermentation, but it might approximate a "worst case scenario" upper limit.

If you do it, stick a liquid disconnect on your gas line so you can actually bubble CO2 through the beer.

Offline erockrph

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Re: Dry hopping during active fermentation
« Reply #16 on: April 26, 2016, 09:54:34 am »
Bubbling CO2 through beer is a well known technique that can scrub aroma and flavors, so why not hops?  It may not reduce IBU but I'd bet it can remove some volatile compounds from dry hopping.  If your fermentation is almost done, it may not remove much in practice.
Good point. The question is how much it would actually remove in practice. I have an old keg of IPA I've been meaning to dump to make room for some new batches. Maybe I'll throw a couple of ounces of hops in the keg for a few days then go through some purge/degas cycles to see what happens. It's probably more extreme than what would happen during fermentation, but it might approximate a "worst case scenario" upper limit.
If you do it, stick a liquid disconnect on your gas line so you can actually bubble CO2 through the beer.
I would think that repeated pressurize/purge cycles would be a closer approximation of fermentation than actually bubbling CO2 through the beer.
Eric B.

Finally got around to starting a homebrewing blog: The Hop Whisperer

Offline narvin

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Re: Dry hopping during active fermentation
« Reply #17 on: April 26, 2016, 11:30:45 am »
Bubbling CO2 through beer is a well known technique that can scrub aroma and flavors, so why not hops?  It may not reduce IBU but I'd bet it can remove some volatile compounds from dry hopping.  If your fermentation is almost done, it may not remove much in practice.
Good point. The question is how much it would actually remove in practice. I have an old keg of IPA I've been meaning to dump to make room for some new batches. Maybe I'll throw a couple of ounces of hops in the keg for a few days then go through some purge/degas cycles to see what happens. It's probably more extreme than what would happen during fermentation, but it might approximate a "worst case scenario" upper limit.
If you do it, stick a liquid disconnect on your gas line so you can actually bubble CO2 through the beer.
I would think that repeated pressurize/purge cycles would be a closer approximation of fermentation than actually bubbling CO2 through the beer.

Why is that?  Unless you're shaking the keg, it's just going to go in the headspace.  Fermentation is releasing CO2 that is escaping through the beer.

Offline hopfenundmalz

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Re: Dry hopping during active fermentation
« Reply #18 on: April 26, 2016, 12:28:14 pm »
I always wait until fermentation has completed.  That way the CO2 does not carry the hop aroma out of the fermenter as it escapes and instead stays in contact with the beer.
I'm going to call BS on this as an old brewer's tale that just makes no sense to me whatsoever. If the hop oils are in solution, then there is little risk of CO2 in gas form removing it from the beer. Hop aroma compounds aren't some magical substance that evaporates rapidly at room temperature (after it is already dissolved in solution, mind you) if you look at it the wrong way.

As far as I understand, during the dry hopping process you are not extracting any significant amount of oils from the hops and instead are just taking some of the fragrance? In order to extract and isomerize oil from hops and imbue your beer with it, you need to reach a temperature of 175 F or so (at least for bittering purposes).  If that is true, it seems to me that a sealed environment or at least one that was not constantly being purged with CO2 would be better. It would be awesome to see some research on it as I am just speculating.
Dry hopping gets the oils into the beer, and is about the only way to get some of the oils to stay in the beer as those are volitile.

Dry hopping with active yeast gives the boitransformations that can create some floral and fruity aromas. Stan Hieronymus has written a fair amount about that, and dry hopping in general.
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Offline erockrph

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Re: Dry hopping during active fermentation
« Reply #19 on: April 26, 2016, 12:35:20 pm »
Bubbling CO2 through beer is a well known technique that can scrub aroma and flavors, so why not hops?  It may not reduce IBU but I'd bet it can remove some volatile compounds from dry hopping.  If your fermentation is almost done, it may not remove much in practice.
Good point. The question is how much it would actually remove in practice. I have an old keg of IPA I've been meaning to dump to make room for some new batches. Maybe I'll throw a couple of ounces of hops in the keg for a few days then go through some purge/degas cycles to see what happens. It's probably more extreme than what would happen during fermentation, but it might approximate a "worst case scenario" upper limit.
If you do it, stick a liquid disconnect on your gas line so you can actually bubble CO2 through the beer.
I would think that repeated pressurize/purge cycles would be a closer approximation of fermentation than actually bubbling CO2 through the beer.
Why is that?  Unless you're shaking the keg, it's just going to go in the headspace.  Fermentation is releasing CO2 that is escaping through the beer.
Actually, I was thinking more along the lines of force carbonating, then venting several times (as if you were trying to bleed off pressure from an overcarbed beer). Depending on how fast it loses pressure, I'd consider re-carbonating part way through and repeating the process.

I'm just thinking that bubbling through the beer would be a lot more vigorous than what actually happens during fermentation, and would also present a lot more surface area as well.
Eric B.

Finally got around to starting a homebrewing blog: The Hop Whisperer

Offline blair.streit

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Re: Dry hopping during active fermentation
« Reply #20 on: April 26, 2016, 02:41:18 pm »
I'm just thinking that bubbling through the beer would be a lot more vigorous than what actually happens during fermentation, and would also present a lot more surface area as well.
Yeah, it seems if you wanted to accurately recreate fermentation-type bubbling you'd need something to widely disperse a low volume of gas slowly over most of the bottom surface of the beer. Almost like a big false bottom with very tiny holes. Then you'd need some kind of one-way valve to make sure beer doesn't come back into your gas line due to the hydrostatic pressure.

Maybe you could just use a few different 500 micron stones in a "hydra" type configuration weighted near the bottom. My pediatric O2 regulator will do 1/32 LPM, but even that seems like it might be too fast. There are probably good "cap and capture" resources out there that estimate the volume of CO2 produced by a specific sized yeast colony at a specific temperature and gravity. Wow, this is starting to sound fun (and complicated).

Offline zwiller

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Re: Dry hopping during active fermentation
« Reply #21 on: April 26, 2016, 04:58:48 pm »
Definitely different schools of thought.  Last IPA I held off on the dry hops until fermented out, crash cooled until bright, raised to room temps, and dry hopped 7 days swirling a few times to re-suspend and I think it's the best results I've ever gotten in a long time.  Some of the big namers have bypassed CO2 rousing completely and gone full tilt pump recirc dry hop. 
Sam
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Offline denny

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Re: Dry hopping during active fermentation
« Reply #22 on: April 26, 2016, 05:05:22 pm »
My own testing has given me better results by dry hopping after removing the beer from the yeast.
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Offline hopfenundmalz

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Re: Dry hopping during active fermentation
« Reply #23 on: April 26, 2016, 05:19:48 pm »
My own testing has given me better results by dry hopping after removing the beer from the yeast.
I have good results doing both sequentially. Nobody told me I couldn't.  ;D
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Offline denny

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Re: Dry hopping during active fermentation
« Reply #24 on: April 26, 2016, 05:36:47 pm »
My own testing has given me better results by dry hopping after removing the beer from the yeast.
I have good results doing both sequentially. Nobody told me I couldn't.  ;D

That is supposedly what Leo Fender said about the electric guitar he invented....nobody told him you couldn't do that.  You have a good model to follow!
Life begins at 60.....1.060, that is!

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Offline westcoastbrew

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Re: Dry hopping during active fermentation
« Reply #25 on: April 26, 2016, 09:06:51 pm »

Dry hopping gets the oils into the beer, and is about the only way to get some of the oils to stay in the beer as those are volitile.

Dry hopping with active yeast gives the boitransformations that can create some floral and fruity aromas. Stan Hieronymus has written a fair amount about that, and dry hopping in general.

Thank for the info, I will check that out.