Coffee Science Update

Wednesday, March 18, 2009 

Magnetically stirred coffee seems to be a success, but still tuning the parameters. I have a surplus temperature control module connected to a thermocouple probe to monitor the temperature.
My first attempt was confounded by not programming the controller to read a K-type thermocouple, it came set for a J-type and so the water never got over 88C even boiling… which it did for a while and that’s not good. Not good at all.
Today I let the water temp get up to 80C and the coffee was very good, smooth and not bitter at all. Perhaps a bit too smooth, a bit like the cold-brew taste but warm and much faster thanks to the stirring action. I will try 90C tomorrow and if success continues, modify the hotplate to add a direct thermal element bypass to the outside so the temp controller can control the heater directly (now I just watch and turn off the heater at the target temp.)
The theory is that by continuously stirring the coffee, a lot of flavor is extracted without relying on heat, and that the stirring also ensures uniform heating through the entire volume and thus the temperature can be set fairly precisely (to about a degree C, +/- 1 degree or so) to optimize differential extraction of the organics in the grounds.

Posted at 16:00:26 GMT-0700

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