Prevent oxidation by storing coffee beans in CO2…

I originally wrote this in June 2010 and, frankly, it was a mess – full of typos and half-developed ideas. How I ever let it slip by me I really have no idea. Was I ill at the time? Did I, as I strongly suspect, already have Addison’s? I don’t know, but I do know it badly needed re-writing, which I’ve done, below, and hidden the original so as not to confuse Google. Changed the title too.


Pretty much the biggest enemy of coffee beans, in storage, is oxidation. The Italian company, Illy, gets past this, with some of their beans, by packing them in nitrogen, which simply isn’t feasible for domestic use. I thought about using CO2, which logic suggests should be effective (after all, after roasting coffee beans outgas CO2), but information was elusive.

At the time I’d bought what turned out to be a very disappointing book, The East India Company Book of Coffee. In online appearance an average coffee-table book but, in reality, the world’s smallest – about 6” x 4”, with a mere 64 pages – it nevertheless contained an extremely useful nugget of information. You can use CO2 to protect coffee beans. But how?

My first thought was adapting a CO2 tyre inflator, but that turned out not to be feasible, as the blast of gas is uncontrollable and likely to blow beans all over the room then, on a scuba-diving website – taken there chasing down links – I found a link to Not only do they sell more CO2 cartridges than a hound’s got fleas, they sell tyre inflators, naturally enough (got one for my powerchair as an onboard backup), they also have keyboard blowers – so I ordered the MOSA keyboard blower. The gas is dispensed through a thin nozzle, operated by a trigger, so it’s easy to control. There’s just one problem – as the compressed CO2 expands, its temperature drops way below freezing – and I mean frost-bite level cold, at least it does according to the website. In use it’s not a problem.

Experience has shown that while the CO2 cartridge will freeze to your fingers in use, the emerging gas, while cold, isn’t dangerously so. I wouldn’t recommend blasting hot computer components with its chill, but it won’t freeze me unless I do something very stupid.

My idea is to push the tube to the bottom of a jar of beans, and give it a burst of gas – the velocity of the gas should displace the air, rather than simply merge with it, though even if that’s what it does it’ll be an improvement.

A better alternative might be to put the beans in a freezer bag, suck out the air as you would for freezing, then quickly slip the CO2 tube in and inflate it. That would  certainly be more efficient.

Of course, the process would have to be repeated every time you take out beans, but taking out a week’s worth at a time won’t harm the beans that are removed, and cut down on gas use. The 16g cartridges the MOSA blower uses contain 20 cubic metres of the stuff, and 10 currently cost £5.74 – compared to what you’ve invested in coffee making equipment and the coffee itself, that’s buttons. You can buy bigger packs – of 30, 300 or 1,000 cartridges – should you have a real urge to contribute to global warming! Trouble is, I’m not convinced by the 20cubic metres claim. Yes, I know that’s at atmospheric pressure but, frankly, it doesn’t last very long in use. Still, if it keeps the beans in good condition for longer, it’s probably worth it. It’s at least worth trying, and the blower itself is only £4.16 including two cartridges.

The easiest way to get the gas deep into the beans is to use a drinking straw, or two, to extend the blower’s nozzle – scrounge a few from the pub, or buy a pack – they’re cheap, £1.60 for 225 (multicoloured, flexi), or £1 for 100 (black, not flexi), both from Sainsbury’s.

A caveat: On a bike or a wheelchair, CO2 leaks out through the inner tube material, and I know from experience that freezer bags are microporous, so might have the same problem. And I’ve read – from an expert – that freezing coffee beans does nothing at all to extend their shelf life that keeping them in the fridge doesn’t do.

Your call.


One thought on “Prevent oxidation by storing coffee beans in CO2…

  1. Update: I went with the freezer bag option – Lakeland’s Soup ‘n’ Sauce bags – very thick plastic and much easier to use than jars. Re-usable, too, as they’re very robust.

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