Popping in for a Coffee: Roasting your own beans at home

Another great guest post by Matt Gibson.

The other day, I woke up and realised I had no coffee in the house. The fact that this realisation terrified me might give you some idea of the relationship I have with caffeine. It's a geek thing.

Luckily, I remembered I *did* actually have some coffee. The only problem was that what I had, tucked away in the back of a cupboard, was a bag of unroasted green beans.

So. Out with the popcorn maker!

Yes, the popcorn maker. I've had one hanging around since I read a fellow geek's blog post about how you could convince a hot-air popcorn maker to roast coffee beans. A week after I read that post, I saw one going on Freecycle. They're just the kind of appliance that people buy on a whim, use twice, and then relegate to the back of a cupboard until the next clear-out, so Freecycle is a pretty good source for them.

The next bit is more easily shown than told, so, without further ado, here's me, on a Saturday morning, making a cup of coffee all the way from a handful of green beans to the mug:

The coffee tasted pretty damn good. It helps that green beans last for *ages* compared to roasted beans, which is excellent motivation for home roasting.

If you want to try this at home, (a) see if you can find a friend with a popcorn maker they've not used since 1988 and steal it, and (b) look to somewhere like Has Bean for supplies – all their beans are available to buy green.

Enjoy! But do bear these caveats in mind:

• The same hot air that's designed to lift the popped corn out of the machine also blows out the chaff (the papery "skin" of the beans.) The chaff starts floating off soon after you put the beans in the machine, and is much harder to catch in a bowl than popcorn. Be prepared to sweep up afterwards.
  
• You normally roast coffee to somewhere between first and second "crack". Each coffee bean makes a sharp little cracking sound once, near the beginning of the roasting, and then again, a few minutes later in the case of my popcorn maker. The longer you leave it, the darker the roast, which I like, but it's a fine line between "French roast" and "burned to a cinder". This guide may help.
  
• Coffee roasting takes longer than popping popcorn. Be careful your popcorn maker doesn't overheat! Watch for deforming plastic, etc. Don't leave it unattended. Basically, don't try this at home, kids, unless you're prepared for unexpected consequences.
  
• You can, of course, buy "proper" home coffee roasters, but they're more expensive. And less fun, in my opinion, than repurposing something orange and plastic from the 1980s and bending it to your will.
  
• If you're going to point an expensive camera lens into a hot-air popcorn maker's exhaust port, make sure you do it from a safe distance. I got away with it, luckily.
  
• You probably want your beans to "rest" a while after roasting to "de-gas" them. The typical advice is to wait around a day between roasting and using the beans. In practice, though, the coffee tasted fine to me straight away, but that might have been because I was caffeine-starved :)