Oxidation from dry hopping in the keg?

I wonder if bubbling CO2 up from underneath would help scrub some of the O2? Put the hops in, rack the beer in, bubble CO2 up from the bottom of the keg through the beer and hops. I don't seem to have the issue you have. I transfer via CO2 forced racking, and at the end of the transfer I always have CO2 flowing from the now empty fermenter through the racking cane down to the tubing exit at the bottom. Helps blow off the O2 that may have filled the headspace during racking, and could be evacuating O2 from the hops in the bag too. Worth a shot. You could always hit it with CO2 through the out post for a few seconds and see if it helps.

 

Yes, that should work fine.

 

From my experience, heavily dry hopped beers (IPAs) last months if lagered after a short time at room temp. Oxidation seems to come mostly from marginal hop quality and storage (infrequent). How much purging do you do?

 

I have a related question: how long do commercially kegged hoppy beers (IPAs) last?

Anecdotal story: This past season Troegs packaged Nugget Nectar in sixtels in December 2013 but for some reason did not release them to bars and beer consumers until the February 2014 timeframe (i.e., the kegs were already 2-3 months old before tapping). I just happened to be at a local beer bar (TJs Everyday) when they tapped their first keg of Nugget Nectar and the bartender came up to me with a disappointed look after tapping the keg and stated: “I looked at the keg label and it listed that it was packaged on December x, 2013” (I can’t recall the exact day). That beer definitely suffered from hop fade.

I know that a BA purchased a sixtel of Nugget Nectar for his kegerator in February and in a thread expressed his disappointment in the age of the keg; the beer suffered from hop fade.

Cheers!

 

I would think that would vary greatly between different breweries based on their process and equipment.

 

Either way, I don't understand why they did this.

 

Some breweries use hop cannons these days. Pellet hops go into a small vessel, purged of O2, then shot into the fermenter under high pressure.
http://www.dogfish.com/community/bl...eekery-behind-the-scenes-with-me-so-hoppy.htm

Some dump the hops into the fermenter.

 

It's a concern commercially, and lot of breweries use different methods to control O2 exposure when dry-hopping:

http://www.mbaa.com/districts/MidSouth/Events/Documents/2012-11-02MellemDry Hop.pdf

My dry-hopped beers do have oxidation issues after about 6 weeks. It's more of a little harshness, and some hop fade, still definitely drinkable. I haven't done anything to mitigate it, but was planning on trying the "add hop bag to keg, pressurize with Co2, then purge" method for the next one.

It may be that I'm more sensitive to it, the wife doesn't notice a difference.

 

O2 from the dry hops is worrysome to a few larger breweries. I have read about one (can't remember which and where I read it - it is a very large and well known brewery) will dry hop in the fermentor just short of final gravity. The still active yeast will consume the remnants of any remaining O2 in the hops themselves.

To answer your question though, yes, I think that adding the hops to the keg, purging the keg with CO2, and then racking the beer into the keg would help reduce/remove any O2 in the hops themselves.

I am not a fan of hitting the beer with CO2 from the bottom tube of the keg, while it may scrub oxygen, I am guessing it will also scrub some of the delicate essential oils into the headspace.

 

Matt, I think you are referring to Sierra Nevada. Below is information that Bill Manley (@sierranevadabill) shared within me in a BA online conversation.

You also might be interested in knowing that Sierra Nevada employs a differing dry hopping method for Celebration (vs. using a Torpedo). From the Stan Hieronymus Hops book: “Sierra Nevada Brewing uses two different methods to dry hop with cones. One is to attach eight-pound bags, which will be more than four times heavier after absorbing beer, to rings that have been welded to the sides of tanks. Celebration, BigFoot and other small run beers will soak for up to two weeks. They are then transferred into another tank.”

Cheers!

Jack

“Hi Jack,

This IS true. We start running the Torpedos when we have about ~2 degrees Plato (1.004 - 1.008SG) left of fermentation to finish, and then continue to run the devices after full fermentation has ceased and the beer is cooled.

The cool thing about the Torpedo itself is, by adjusting what temperature the beer is when using it, when we start and how long and fast we run the pumps, we can really manipulate the aromas in the finished beer.

We start running the Torpedos during fermentation because A. the beer is warmer at the start, and B. the roiling fermentation helps to keep the hop oils in circulation as the beer runs from the tank and then back to it.C. Running the torpedo with yeast still in the tank helps develop an interesting flavor combination of the yeasty esters and the hop aroma, that mimics traditional (nylon bag) dry-hop aromas. NOTE: Traditional nylon bag dry hopping is almost always done with some active fermentation underway to counterbalance and drive-off the oxygen in the hop charges, and to recirculate the oils.)

Hope this helps,

-Bill

 

I'm pretty sure Firestone Walker does this. IIRC, there was an interview with their head brewer on the Brewing Network website, and he talked about this as part of a show on cloning Union Jack. I've adopted this technique, and while I haven't tested it in any systematic kind of way, my subjective impression is that it works.

 

Firesone Walker? Matt B has talked about some hop compounds being transformed by the yeast.