I've been brewing for a few years now and lurking here nearly as long. I've bottle conditioned everything I've brewed, and when I decided to get serious about post-packaging oxidation a year-or-so ago this thread was my best resource. I don't have the photographic evidence that some of you have gathered, but seeing the thread revived makes me feel compelled to make an account and share the lessons I've gleaned.
I'll spare you the coming essay if you don't want to read it. I hooked a paintball CO2 tank to a mini regulator (via an adapter), the regulator to a thumb valve from a basic air compressor, and that valve to an 'aeration' wand. The wand screws into the thumb valve so it's easy to sanitize by removing and boiling in a second pan along side the priming sugar. When bottling, I first empty the bottling bucket, filling all bottles to a normal head space and laying an uncrimped cap on top. Then just before capping the whole lot, I dip the CO2 'aeration' wand into the neck of each bottle and let the CO2 flow at VERY low pressure for just a few seconds. This creates a fine foam of CO2-filled bubbles filling the entire headspace for 10-20 seconds before it begins to collapse, giving me time to lay and crimp the cap with effectively no headspace at all. This method has been INCREDIBLY effective for me and meshes in easily enough with my normal bottling routine that I do it for every batch, not just the hoppy ones.
So onto the long version:
I, independently through trial and error, arrived at the same conclusions as all of you in this thread: Yeast are very effective at neutralizing oxygen, but only dissolved oxygen and only while they are actively fermenting sugars.
This being the case, any oxygen introduced by racking to an open bottling bucket and stirring to distribute the priming solution (as I do) just contributes to DISSOLVED oxygen. Dissolved oxygen which the yeast, woken up by the fresh boost of sugar, scavenge before it can do any real harm. The actual enemy to fresh-tasting bottle conditioned beer is the oxygen trapped in the headspace that dissolves into the beer after the yeast are finished carbonating. Again, I think I'm preaching to the choir. My only hot take here is that any efforts to reduce dissolved oxygen beyond normal homebrew procedures (like bottling straight from the fermentor with sugar drops/etc or pre-purging empty bottles) are barking up the wrong tree.
So, the issue is: how best to purge the oxygen from the bottle's headspace?
The professionals "Cap on Foam" to great success. The principle is that CO2 escaping solution is naturally trapped in bubbles by a beer's head. This pure-CO2 foam fills all of the dead space in the can/bottle/keg, leaving no room for any oxygen-laden atmospheric air, then the package is sealed up for good. The difference is that they're packaging fully carbonated beer. Without force carbonating, there is just not enough CO2 in solution to form much of any head.
I thought to myself: fundamentally, there can't be much difference between a bubble of CO2 breaking out of solution versus the very smallest CO2 bubble some separate tank can make. Well, there are plenty of aeration stones that can produce an army of tiny bubbles but sanitation becomes a major concern if I plan to dip it into every single bottle of nearly-finished beer. Sure, there are stainless steel 'sintered stones' that can easily be boiled, but the cost of this theoretical project is really starting to add up. Not to mention, avoiding pressure tanks and regulators was a minor point of pride that (not really) justifies the extra effort I spend bottling versus kegging.
So I sat on the idea for a year or two, honing what this system would actually look like until I was fed up enough with cardboardy beer to bite the bullet and make this prototype.
A full 5-pound CO2 tank seemed excessive and disposable cartridges seemed wasteful, so I settled on a 20oz paintball tank
for my CO2 source (I got 10 batches from the first fill, my LHBS charges $5 to refill). You definitely will need a mini regulator like this one
to keep the pressure at just a couple PSI and an adapter
to mate it to the paintball tank. For the aeration wand, I went with Anvil's
(because I liked it's narrow diameter, plus the seamless, all-stainless construction; I did have to hack saw it down to a more manageable length though) but there are definitely cheaper alternatives. So that I don't have to adjust the mini regulator on to just the right pressure and then off again for every bottle, a valve in between is necessary. A thumb valve
for an air compressor blow gun is cheap and adaptable. Some vinyl tubing, plumbing adapters, and a few John Guest push-to-fit connectors later, and I had a useable rig.
I'm away from all of my homebrew kit at the moment or I'd take some pictures. I'm planning on bottling a brown ale this weekend and can come back with photos if anyone's curious enough, but I've attached a Microsoft paint diagram in the mean time.
This set up has been unbelievably effective for the last 13-ish batches. Even IPA's stored warm for months are fresh and bright to the last bottle. I'm planning a true hazy IPA for my next brew, so that will be a tough test. As an added bonus, having an independent CO2 tank also gives me the ability to purge the headspace of fermentors after a dry hop or any other time I break its seal.
The whole purging process only adds maybe 15-20 minutes to my usual bottling routine. I boil the steel aeration wand while I prepare the priming sugar, the rig only takes a couple minutes to build with the push-to-fit adapters then calibrate the pressure, and it only takes ~5 seconds to fill the neck of each bottle with foam. To clean the wand, I put a short length of tubing over the threads that screw into the thumb valve (same diameter as a standard bottling wand's tubing) and push PBW through a vinator
pump through the wand; pump with fresh water to rinse then dry. It's a small enough effort that I do it for every single batch I brew these days.
I'd estimate that my shelf life has tripled, at least. Truly dramatic. To give credit to others in this thread, I did see more or less the same effect when I tried filling bottles to the very brim with beer. But between the risk of bombs (not something I experienced but still scary), the lack of hiss, and the ~3 seconds before the bottles foamed over, I found that method unsatisfying and more trouble than it was worth. This cap-on-foam rig I came up with is expensive, admittedly. But it is also effective, quick, easy to use, and the fill height after the foam collapses remains 'normal.'
Almost everyone in my local brew club kegs, so other than my own taste buds you dorks are the only ones that will really appreciate all of this effort. Any thoughts or criticism appreciated.
Relax, Don't Worry, Have a Homebrew