Oxygen absorbing bottle caps for longterm home-brew storage

Originally published at: http://boingboing.net/2016/09/13/oxygen-absorbing-bottle-caps-f.html

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Cap on foam … boom, no o2 trouble!

^ guess I should explain a bit more…
This is when you have the ability to keg. 1) Carbonate in the keg to perfection 2) fill the bottle, making sure to foam up a bit at the end. 3) Cap on the foam.

Not for use on the international space station, or in submarines for that matter.


That’s not useful, necessarily, for something like a barley wine. With styles like that you’re looking for long aging with natural carbonation and bottle/cask conditioning. Force carbonation doesn’t get you anything but carbonation, and Kegs don’t solve Jason’s distribution problem. But the long conditioning sees the yeast re-consuming non-alcohol, non-sugar fermentables and thus changes (usually improvements) in the beer. Removing oxygen prevents oxidation which creates bad changes in the beer (below a certain ABV, and in certain styles supposedly). And from what I understand Barley Wine needs that sort of conditioning to be drinkable. At least 6 months in bottle IIRC the last time I looked into making one (why I didn’t make one). You could, presumably condition in the keg, then carbonate after. But I don’t think they’re really suited to that. Though most of the kegging equipment (discounting the forced gas components) should cross over to cask conditioning.

Personally I dunno if I’d ever get interested in kegging. Its got a lot of convenience to it. But I like the results I get from a couple months of bottle conditioning. And most of the styles I’m interested in making seem to go well with the natural conditioning approach. But I haven’t done a batch in a long while, so I’m more than a bit removed from the pain in the ass that is dealing with bottles. And I’ve already decided I’m not interested in re-using commercial bottles again.

@jlw I’ve heard these things are great generally for reducing spoilage. Even in bottlings that’ll hang around for shorter times. But for things that get conditioned for a long time, like Barely wine is supposed to. Or anything you might plan to cellar. I’ve been told champagne style corks are the gold standard. They’re a little more permeable than a crown cap, so certain kinds of natural gas and moisture exchange (like oxygen getting forced out by co2) that are beneficial to the beer (or can lead to spoilage!) can still take place. These caps will apparently keep your beer more stable than regular caps. But stable isn’t always what you want.


I cask condition in kegs. I like those results too. I use 2.5G corny kegs and they’re OK for bringing to a bbq or picnic, but not nearly as handy as a 6 pack.


What is the technology here?

Does the cap absorb o2 indefinitely, or is there a max saturation? Are the caps shipped individually wrapped in an oxygen free environment? Would an oxygen sanitizer also saturate the cap?

The owner of my local home brew shop brings in ales that are more than 3 years old, and are delicious!

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This is a very good question. The ones in my Local Homebrew Shop are just bagged, no special environment.

I’d also be interested in hearing the results of a blind taste test. This always seems to be the kind of thing that no one has any actual idea of whether it affects the taste or not.

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What’s the process there? I only know kegs and casks from the service side. Do you condition as normal then dispense under pressure? Or via a cask pump, gravity or party tap? Or are you conditioning and then force carbonating later to sort of split the difference?

I’m not gonna speak for @jlw, but I’m a cask conditioned, English beer enthusiast.

Condition as normal, and when you want to serve you have a few choices. Light oxidation is nice, but it isn’t stable for aging. So the moment you crack a keg, you have about a week to serve it all. An Angram beer engine is the gold standard, but practically for home brewers you age and condition with the keg horizontal (for soda kegs). Then you gravity pour.

For sankes you really have no option but to use an engine.

Generally I would purge the kegs nightly with CO2, but you don’t serve under pressure. You open your kegs gas valve and let air in.

I cask carbonate with sugar, use co2 to pressure booze out of the keg. Never introduces air.

First pint is all yeast.

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Whenever I’m at a bar/brewpub that has a cask on tap, I’ll usually order that, whatever it is, partly because I prefer a little less carbonation than apparently everyone else does. Problem is, cask conditioned shouldn’t be an excuse for “flat”, which it sometimes is.


They activate when wet, so they ship loose in a sealed plastic bag. You do not sterilize them.

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From what little I’ve read, you can sanitize them, but the information about which sensitization is ok is less than clear. I’ve seen UV, suggested, as well as StarSan. I’ve read that boiling is fine/not fine. And that oxygen-based sanitizers should be avoided. Folks seem to agree that you do need to use them once they get wet, though.

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Hmm, what if you left room for a small canary? Canary sucks up all the O2 and dies. Then when other people are trying to fish the worm out of their tequila, you can ask them if you want to try a REAL drink.



I figured as much. As @japhroaig mentioned traditional cask service involves kind of the opposite. The cask is never pressurized and ambient air is let in. A certain amount of oxidation is desirable from the stand point of traditional British cask ales. Though your likely not making exclusively British cask ales, and commercially a lot more is going on with cask than just that these days. Either a gravity tap on an open cask is used. Or a beer engine (basically a hand pump) is used to suck the beer out of the cask, and the resulting vacuum pulls in air. Its all effectively the opposite of a party tap. Ambient air is introduced, but the beer is never really pressurized above ambient pressure. I think the only effect that has is in terms of carbonation. Its terrible for long term preservation, but results in some nice, typically cask beer like flavor.

Some modern beer systems let you pump in inert gas to displace the air, usually with nitrogen. I’m not aware of any out of the box solutions. Most of this sort of thing is a custom build on a per-bar basis. Like those “flux capacitors” that were all the rage a bit back. Basically custom assembled collections of regulators and beer lines arranged for display and easy access. All this stuff is assembled as needed from standard parts to fit whats needed so I’m unsure how they accomplish it, and I doubt there’s a standard solution.

Problem is that casks are functionally open to the air, which is bad for preservation and maintaining carbonation. Casks are kept small to mitigate, but without some speedy sell through its going to go bad much faster than a keg. I almost always go for the cask when its available, but if the staff has the time I’ll ask how long its been opened so I know what to expect. I’ve had a few bartenders warn me off, because they don’t sell enough cask for it to stay fresh (we can smell our own). Oh and some of the beer engines use a “sparkler” attachment, basically causes a more turbulent pour. Pouring rougher gives a better head but drives off carbonation, regardless of what beer form you’re talking about.


If you think Pizza discussions or Ketchup on Hotdog discussions can get violent, you’ve never been in a heated sparkler war.


Eh things are cool certainly. And I’ve had some good beer out of them. And I can see why aerating the beer would be good. It does similar flavor things to wine, and you might want to tame the carbonation on a freshly tapped cask. But it would seem to aggravate the whole “unless you pour it fast enough it goes flat and over oxidized” thing. Aggravating the short comings that had everyone adopting kegs to begin with. So nice idea, good in the right place with the right beer. But I don’t see how its an option for the default.

Its like the Guinness nozzle. It works great for nitro beer with the right body/gravity. But you wouldn’t go pouring a co2 force carbonated pilsner out of one of those things, would you?

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I read someplace that in your situation one should sit back, relax, and have a homebrew.


Love the topic.

Be aware that the shelf life of O2 absorbing crowns is pretty short and that most breweries have moved on to O2 barrier crowns as a better option.

I am a big fan of cask conditioned product and yeast activity will provide way more O2 scavenging ability than a crown could.



Psst. @renoun