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The Wish List

8Sep09

When Elly and I return from Bulgaria, I want to build a new roaster. This is partly for something fun to do, and partly because I’ve been thinking about the coffee roasting process and how we might make a roaster which ticks a few more boxes.

Here’s my wish list for the ideal roaster for our requirements:

  1. Designed such that the beans are roasted evenly and gently;
  2. Powerful enough to bring 1-2kg of green beans to second crack in 15-18 minutes;
  3. Consistent and reliable – able to reproduce a given roast profile;
  4. Highly adjustable and reactive heat source(s);
  5. Gentle, preferably adjustable air flow;
  6. Adequate removal of chaff from heat source(s);
  7. Efficient use of heat.

I suspect that there are many commercial 2kg drum roasters which more or less fit this list of specs. They would, of course, cost me over AU$5000 and this is not really an option!

For comparison, here’s what we’ve been roasting with (in one form or another) for the last 18 months or so:

The humble Corretto roaster.

This is taken without the mesh chaff-catcher we use. We also use a solid metal thermocouple instead of the wire type shown. This looks like about 500-600g; we can do 800g easily.

I won’t embed it here, but there’s also an (outdated but cool) YouTube video we made.

Our Corretto is fantastic, and has served us well for about 200kg of green beans, but I suppose I’m always looking for ways to improve stuff. Pretentious, I know.

Problems with the Corretto (some of which we’ve encountered in the past):

  • batch size is limited to about a kilo – not a problem for most people, but I’d love to be able to do 2kg!
  • heat source (a heat gun) produces a fairly concentrated, quite hot stream of air. This can cause tipping (burnt ends on the beans) because it’s too harsh.
  • air flow is quite high, which may dry the beans out too much (that’s my theory – our beans average 17% loss of original weight and I suspect 15% is adequate).
  • chaff flies everywhere (unless you build an ingenious chaff catcher like we did).
  • depending on your heat gun model, reproducing previous roasts can be a challenge.

I’ll be addressing how one might improve the Corretto in another post; I just mention that list here as a comparison to my wish list.

Cheers

Stuart.

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