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How Hot Is Too Hot?
Small 500g drum electric roaster with 6 inch diameter by 7 inch long bean drum housed within a 8 inch diameter by 10 inch outside drum. My question is at what temp would be considered too hot for air temp inside drum?

I've heard that 525F is the hottest environment temp you want.
Yep, 270C here
Roasters: DIY: TO based IR 640g
Moded commercial: Dieckmann RoestMeister, Nesco, popper(s).
Electrics: TC4ESP, MS6514, USB/Artisan/Apps, PID controllers
Grinders: Arco, Xeoleo ghost burrs, Krinder, vintage PeDe Dienes, MBK Feldgrind
Brew: Flair, Kompresso, Rota Aeropress, Hario Cafeor dripper, Gaggia Mini
I'm copying this from Carl Staubs guidelines from a while back which is where MET was born. Please be aware that it was only intended to be a guideline for drum interior air temp max.

Maximum Environment Temperature (MET)
Establishing the thermal environment protocol for the ideal roast is a balancing act. While it is desirable to maintain the BRR temperature and energy levels until the target reactions are achieved, the BRR temperature is well above the carmelization temperature of sucrose. Because many roasting systems exhibit thermal hysterysis using simple temperature regulating schemes, care must be taken not to allow the coffee mass to exotherm. Additionally, limiting the maximum environment temperature, MET, is also important. As previously mentioned, maintaining structural integrity of the cellulose matrix is of great importance. Lower temperatures will reduce surface evaporation of constituents minimizing the capillary action that draws constituents to the surface where they would be volatilized. Hydraulic action, a function of internal pressure which is directly related to bean temperature, is already at work. By limiting the maximum temperature, losses will be minimized and the essence of coffee retained. Consequently, the MET should not exceed 520 degrees F. This roasting system bases the MET value on the actual final bean, or drop temperature, which correlates to the degree of roast.

1/2 lb and 1 lb drum, Siemens Sirocco fluidbed, presspot, chemex, cajun biggin brewer from the backwoods of Louisiana
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