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Evidence of an Exothermic Reaction While Roasting Coffee

Barry Jarrett of Riley's Coffee and Fudge, St. Louis and of alt.coffee fame plotted this chart on his Diedrich shop roaster showing evidence of an exothermic reaction near the end of an experimental roast. The roaster heat settings were not changed during the roast. The reaction was so significant that it actually increased the heat inside the roaster. Note the rising roaster temp curve near the end. The rate of temperature increase of the beans was greater than the rate of increase of the roaster temperatures as shown on the graph. Clear evidence that an exothermic reaction was actually generating heat.

These are coffee roasting temperature curves from a Diedrich shop roaster.

Comparison between bean temperature measured in the bean mass and roaster air temperature.

Download the raw graph database- 121802XX.xls

Right click and choose 'Save Target as...' to download the file.

The Homeroaster ™ is dedicated to helping the coffee homeroaster explore, find, acquire, roast and brew coffee to achieve the ultimate coffee experience. If you have suggestions for articles or information concerning homeroasting, please send them to me. Great things are coming in the near future for homeroasting, and I am excited about the possibilities! Please check back soon for great homeroasting information and opportunities for coffee homeroasters!

Ed Needham


Quote of the day..." Drink Good Coffee. You can sleep when you're DEAD! "
author unknown, but passed on to me by Robert Holland on the Homeroast List--Thanks!

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This page revised January 23, 2003