Author Topic: Minimizing Oxidation During Dry Hopping  (Read 10521 times)

Offline mpietropaoli

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Minimizing Oxidation During Dry Hopping
« on: February 09, 2016, 01:30:30 PM »
I can't point to this as the reason, but one of the best IPA's I've ever made (and I make a lot of them) used the Tasty McD-ish dry-hopping method at adding at least one round of dry hops during the final 1/3 of fermentation.  The idea being the CO2 being forced out will help to blow off some of the oxygen (this is actually one of my questions...more below), and that you can compensate for aroma blowoff with...well, more dry hops. 

We are trying this on our latest NE/VIPA (sorry I know some people don't like calling them VIPAs, but I just want to delineate that this is not a bone-dry WCIPA) that is currently 9 days post-pitch in a 14 gallon SS conical, fermented with 50% Hill Farmstead and 50% Conan yeast.  Pitched at 68, raised to 72 at 6 days (~70% AA), currently at 72. 

We are going to add the first round of dry hops (Mosaic/Simcoe/Centennial cocktail) now, and I advised my brewing partner to jack the temp to 73 to facilitate more blowoff. 

My first question is relatively open-ended:  how, if at all, do people minimize oxidation when adding dry hops.  I had heard one method of boiling then cooling water (enough to cover the hops), then adding the hops to that water before adding to the beer.  Intuitively, this makes sense, as we would only be adding 5-6 oz of water, hopefully not enough to materially affect gravity in a 14 gallon batch. 

Second question is how does/could blowoff assist in minimizing oxidation (I think the theory is that the oxygen is actually trapped in the pelletized or dried whole cone hops themselves)?  Do the CO2 bubbles simply 'carry' the O2 molecules out of solution as they head out of solution?  I thought that oxidation actually meant oxygen was BINDING to molecules in the beer, in which case, 'northbound' co2 would pass right by the already-bound oxygen. 

I know brewers like Alchemist claim to have proprietary dry hopping techniques that minimize oxidation.  In fact, I read somewhere that a QC analyst looking at Heady Topper thought that his equipment was malfunctioning (!)  This would explain (along with canning) why Heady can hold up for months. 

Any thoughts are appreciated!
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Offline klickitat jim

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Re: Minimizing Oxidation During Dry Hopping
« Reply #1 on: February 09, 2016, 01:48:35 PM »
If I were that concerned about dry hop oxidation I would do it in a second vessel, add dry hops, purge it with CO2, transfer the beer onto the hops.

Offline HoosierBrew

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Re: Minimizing Oxidation During Dry Hopping
« Reply #2 on: February 09, 2016, 02:13:54 PM »
I crash, use gelatin, wait 2 days then pump out the sediment, then dry hop in keg. The keg is purged before and after filling. Hop aroma sticks around for quite a while.
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Offline braufessor

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Re: Minimizing Oxidation During Dry Hopping
« Reply #3 on: February 09, 2016, 02:45:03 PM »
I do a double dry hop with all of my Northeast type IPA's.

Dry hop #1 goes into the primary fermenter at day #5 so that there is still some fermentation going on to hopefully limit any O2 pick up.

Dry hop #2 is done in a CO2 purged dry hopping keg.  I use a double screen over the dip tube.  I fill keg with star san, push it out with CO2.  Open lid, add dry hops to keg (free, not bagged).  Rack from fermenter onto hops.  Purge head space with CO2 again.  Let it sit for 2-3 days and then jump it from the dry hop keg to a serving keg (purged).  Leaves all the hop material behind.  This is the strategy I use for the dry hop keg - it takes a time or two to get a process down, but once you do, it works great: http://www.bear-flavored.com/2014/09/how-i-dry-hop-my-ipas-with-no-oxygen.html
« Last Edit: February 09, 2016, 06:51:44 PM by braufessor »

Offline pinnah

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Re: Minimizing Oxidation During Dry Hopping
« Reply #4 on: February 09, 2016, 04:02:09 PM »
Cool idea braufessor!

hmm, I get the WCIPA and the NEIPA....but what is a VIPA? ???

Offline denny

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Re: Minimizing Oxidation During Dry Hopping
« Reply #5 on: February 09, 2016, 04:46:39 PM »
Pardon my pragmatism...has anyone ever gotten oxidation due to dry hopping? 
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Offline HoosierBrew

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Re: Minimizing Oxidation During Dry Hopping
« Reply #6 on: February 09, 2016, 04:51:12 PM »
Pardon my pragmatism...has anyone ever gotten oxidation due to dry hopping? 



Not that I'm aware of, Denny. The procedure I posted is more to prevent oxidation from contact with outside air. I don't worry about oxidation from the dry hopping itself. That's overstated IMO.
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Offline mpietropaoli

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Re: Minimizing Oxidation During Dry Hopping
« Reply #7 on: February 09, 2016, 05:22:18 PM »
Pardon my pragmatism...has anyone ever gotten oxidation due to dry hopping?

Carboardy "this-is-oxidation" oxidation?  No. 

However, I did forget to purge a keg one time, 'quick' force-carbed it, and it was basically like a hand grenade went off in the thing in a few weeks.  Acetaldehyde, intermediate ferment compounds, etc.  A great beer became vile quickly. 

I am after ways to keep my beer tasting better, longer.

I have to believe that at some of the flavor stability of a beer like Heady Topper is due to the infinitesimal exposure it gets to oxygen, absence of aroma scalp of a crown, etc.  Granted, it could partially be a recipe issue (my belief is that NE IPA's/VIPAs are more about esters than hop aroma), but I do know that one of the greatest brewers in the world is fanatical about preventing oxidation.  So to the extent I can minimize it, I am going to follow his lead.
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Offline hopfenundmalz

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Re: Minimizing Oxidation During Dry Hopping
« Reply #8 on: February 09, 2016, 06:26:17 PM »
If I were that concerned about dry hop oxidation I would do it in a second vessel, add dry hops, purge it with CO2, transfer the beer onto the hops.
This, use a keg, purge it a bunch after the hops are in.
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Offline blatz

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Re: Minimizing Oxidation During Dry Hopping
« Reply #9 on: February 09, 2016, 06:32:04 PM »
Dry hop #2 is done in a CO2 purged dry hopping keg.  I use a double screen over the dip tube.  I fill keg with star san, push it out with CO2.  Open lid, add dry hops to keg (free, not bagged).  Rack from fermenter onto hops.  Purge head space with CO2 again.  Let it sit for 2-3 days and then jump it from the dry hop keg to a serving keg.  Leaves all the hop material behind.  This is the strategy I use for the dry hop keg - it takes a time or two to get a process down, but once you do, it works great: http://www.bear-flavored.com/2014/09/how-i-dry-hop-my-ipas-with-no-oxygen.html

I do this as well, although I use a surescreen which works fine.

I go back and forth of whether to purge again after adding the dry hops to the sanitized then purged keg and rack the beer on top, or just add the hops to the keg after racking.

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Offline braufessor

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Re: Minimizing Oxidation During Dry Hopping
« Reply #10 on: February 09, 2016, 06:45:41 PM »
Pardon my pragmatism...has anyone ever gotten oxidation due to dry hopping?

In my experience, when I did not take the time to purge kegs and fermenters my dry hopped beer was really hit and miss.  One would be fine/ok...... the next would have all kinds of weird off flavors.  The beers would taste really good coming out of the fermenter.... and then dry hop, keg and they would just go south. 

This was not  the "text book" cardboard type thing.  It was weird combinations of vegetal/diacetyl/stale/harsh....... So, I am not saying it was oxidation (in the traditional way brewers often describe it) is the only thing at play here.  But, there was definitely some interactions between hops, yeast, oxygen (I think) and other compounds going on that were negatively affecting my dry hopped beers. 

When I switched what I was doing...... purged kegs, a bit earlier on the first dry hop, closed transfers...... It all went away.  I would say I have brewed at least 20 consecutive batches of heavily dry hopped beers over the last 6 months and not one of them has had any of the issues I had been experiencing.  Not to say every beer was perfect or anything - but no more issues of a good beer turning into a bad/mediocre beer after being dry hopped.

Now, whether that is purely from oxidation - I would not claim that.  However, I think their are interactions going on that limiting O2 pick up to a minimum seems to help.

Maybe I will have to brew up a couple batches - one with my current method and one with my old method and send you and Drew some bottles for a triangle test.... see if the old weird flavors come back or if there are perceptible differences :)

Offline braufessor

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Re: Minimizing Oxidation During Dry Hopping
« Reply #11 on: February 09, 2016, 06:46:41 PM »
Cool idea braufessor!

hmm, I get the WCIPA and the NEIPA....but what is a VIPA? ???

Not my idea..... I am just good at surfing the inter-webs...  but it really does work quite nicely.

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Offline denny

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Re: Minimizing Oxidation During Dry Hopping
« Reply #12 on: February 09, 2016, 07:19:16 PM »
Pardon my pragmatism...has anyone ever gotten oxidation due to dry hopping?

Carboardy "this-is-oxidation" oxidation?  No. 

However, I did forget to purge a keg one time, 'quick' force-carbed it, and it was basically like a hand grenade went off in the thing in a few weeks.  Acetaldehyde, intermediate ferment compounds, etc.  A great beer became vile quickly. 

I am after ways to keep my beer tasting better, longer.

I have to believe that at some of the flavor stability of a beer like Heady Topper is due to the infinitesimal exposure it gets to oxygen, absence of aroma scalp of a crown, etc.  Granted, it could partially be a recipe issue (my belief is that NE IPA's/VIPAs are more about esters than hop aroma), but I do know that one of the greatest brewers in the world is fanatical about preventing oxidation.  So to the extent I can minimize it, I am going to follow his lead.

OK, I get that beer can be oxidized by not p[urging.  But is there any evidence, either through research or anecdotally, that dry hopping causes oxidation?
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Offline mpietropaoli

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Re: Minimizing Oxidation During Dry Hopping
« Reply #13 on: February 09, 2016, 08:04:51 PM »

OK, I get that beer can be oxidized by not p[urging.  But is there any evidence, either through research or anecdotally, that dry hopping causes oxidation?

This guy does process engineering at ABI and wrote this as his doctorate thesis. 

http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/34093/Wolfe_thesis.pdf

He says the risk is reduced with pellets as opposed to whole cones, but some oxygen ingress is inevitable with dry hopping (it can be mitigated with purging, flushing the hop material, etc.).  He also had a pretty information-rich Reddit thread, but I don't think he went much into oxidation from dry hopping in it)

Again, anecdotally, Kimmich supposedly has his levels down in (I think) the double-digits per billion, which I have to imagine has some effect on the shelf life of the beer (I have had 8-9 month old Heady and it does change, but it is still excellent).  I also think the yeast in that beer is very good at cleaving glycoside bonds, which makes the beer better over time.  Though thats not verified   :D

Not saying other canning breweries don't achieve the same things with some of their beers, I just haven't tasted them.  So I guess in trying to make a great beer, I am trying to eliminate my process flaws one at a time


« Last Edit: February 09, 2016, 08:43:21 PM by mpietropaoli »
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Offline denny

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Re: Minimizing Oxidation During Dry Hopping
« Reply #14 on: February 09, 2016, 08:46:55 PM »

OK, I get that beer can be oxidized by not p[urging.  But is there any evidence, either through research or anecdotally, that dry hopping causes oxidation?

This guy does process engineering at ABI and wrote this as his doctorate thesis. 

http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/34093/Wolfe_thesis.pdf

He says the risk is reduced with pellets as opposed to whole cones, but some oxygen ingress is inevitable with dry hopping (it can be mitigated with purging, flushing the hop material, etc.).  He also had a pretty information-rich Reddit thread, but I don't think he went much into oxidation from dry hopping in it)

Again, anecdotally, Kimmich supposedly has his levels down in (I think) the double-digits per billion, which I have to imagine has some effect on the shelf life of the beer (I have had 8-9 month old Heady and it does change, but it is still excellent).  I also think the yeast in that beer is very good at cleaving glycoside bonds, which makes the beer better over time.  Though thats not verified   :D

Not saying other canning breweries don't achieve the same things with some of their beers, I just haven't tasted them.  So I guess in trying to make a great beer, I am trying to eliminate my process flaws one at a time

Thanks for that info, Mike.  I winder if this is something that's more theoretical than actual.  I've certainly never noticed oxidation due to dry hopping.  Whether that means it doesn't happen for me or I'm blind to it, I don't know.
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