Posted Tue Mar 5, 2013, 9:37am Subject: Relative air temp vs. bean temp.
I am looking for advice. I recently put together SC/CO roaster. It works pretty well, but I want to install a thermometer. I wanted to know what kind of air temp I am looking for inside the roaster. Also, is there a discernable difference between the air temp and the temp of the beans? Now that I think of it, does that even matter? With my previous set up I was using an air popper and the thermometer was placed directly into the beans.
oldgearhead Senior Member Joined: 25 Jan 2010 Posts: 397 Location: Go Colts! Expertise: I like coffee
Grinder: Virtuoso by Baratza Drip: Chemex,Dilongi DCM900 Roaster: 1/2K Fluid-bed
Posted Wed Mar 6, 2013, 5:33am Subject: Re: Relative air temp vs. bean temp.
Michael Sivetz published a lot of data in the 1960's about commercial coffee processing. In his 1963 work, he stated the best temperature for the hot air in a 'continuous' roaster is 450F to 500F. In general, for home roasting, a 'bean-mass-temperature' probe is desired, because a lot of data has been recorded with them. However, if you can hear the cracks and know how to respond to them, a BMT may not be absolutely necessary.
aghaken Senior Member Joined: 14 Sep 2012 Posts: 2 Location: Saugerties Expertise: I like coffee
Posted Fri Mar 8, 2013, 6:43pm Subject: Re: Relative air temp vs. bean temp.
Initially I drilled a hole through the side of the SC and put the thermocouple wire in through that. But it was just measuring the air temp, which didn't tell me much about the beans. So I drilled a hole in the bottom of my SC, brought the thermocouple wire in through the door on the bottom and just bent the end over. It sits in the bean mass and as far as I can tell gives me pretty accurate readings. Of the mass obviously, not the internal temperature. (First crack is around 380° - 385°.) I use temperature mostly as a guide. Some beans will be FC at 415°, some will be darker. I rely more on sight and sound.
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