Store coffee beans in CO2 to prevent oxidation – conclusion.

Well, I now have my MOSA keyboard blower, or Power Cleaner, to give it its proper name.

First impressions are good, and it seems to be well made and robust. The trigger enables fine control, so gas can be released very slowly if you wish, obviating the need for me to cobble up a device to slow it down.

Nor is the gas freezing. I know, from experience, that CO2 cartridges freeze during discharge, but the advice on the website – that the gas is freezing – is wrong. It’s merely cold.

However, if you discharge the thing upside down, which is just plain dumb anyway, you’ll get a blast of liquid CO2 capable of freezing skin. You’ve been warned.

Anyway, the alleged 20 cubic metres per cartridge disappeared so staggeringly quickly I thought the thing must be leaking, but tossing it into a bowl of water, with a new cartridge fitted, didn’t yield a single bubble. Very strange, and it’s certainly not a good idea to waste gas playing silly buggers! And it won’t last long blowing crap out of your keyboard or computer – still cheaper, and safer, than those compressed “air” cans which are mainly butane.

My idea for storing coffee beans in a freezer bag with CO2 works very well, (the gas injection part anyway), and I’m going with that. If you suck the air out first – as if you’re going to freeze the contents (if you don’t know how, ask someone with a freezer to show you) – you don’t need to inflate the bag like a balloon. A 2-second full-volume squirt of gas is all you need.

That was wrong. It’s essential to store in glass (or PET), or in their original bags, as plastic freezer bags are microporous and, as with bike or wheelchair inner tubes, CO2 will bleed away to atmosphere pretty quickly. A short squirt, pushing the nozzle deep into the beans, is all you need.

I prefer Kilner jars, but there’s no denying they’re heavy, and with the current trend for glass fridge shelves, this worries me. Copella apple juice bottles (PET), are very good, and very light (I use them to store lentils – a 750ml bottle holds a kilo of split red). Crespo olives come in light glass jars, but it can be hard to get the smell out. Baxter’s baby beetroot in sweet vinegar come in similar jars and are easier to deodorise using Milton and bicarb (sequentially, not together).

I also put a squirt into the beans in the hopper of my grinder. As there is no air flow through the hopper, the CO2 should remain in there, to a degree, and if it retards oxidation just a little, it’s worthwhile.

Obviously, this is a long way from an industrial purging process, using nitrogen, but for home use, it will suffice.