Daily Doodle – Jan 15

2010 January 15
by Joe Johnston
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Doodling is key to developing an idea. Little sketches that capture a fleeting thought or chain of thoughts can be referred back to and chained into new thoughts. I’ve just been doodling about various geometries… nothing serious at the moment. One never knows, though. A great idea starts with a simple idea that is grown organically into a fully fleshed-out design.

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2 Responses
  1. Kevin Briggs permalink
    January 25, 2010

    Joe,
    Thank you for sharing your ideas and thoughts about coffee roasting.

    I am intrigued by many of your sketches about the roaster. I hope for the best results from your efforts.

    I am interested in “non-contact temperature measurement” (e.g., IR) during the roast process. I am thinking that “something” in the processing environment will affect the process. A TC within a sheath immersed in the beans will conduct energy away from the coffee beans during the roast process and may not give an accurate temperature of the coffee beans during “non steady-state processes” (I consider most of the coffee roast process as non steady-state). An IR temperature measurement device may be effective but I do not know how to isolate the device from the process; glass absorbs IR radiation and would modify the “normal” temperature measurement process. I am thinking that immersing the device within the process chamber is not a very good idea.

    I am also interested in measuring the color change of the coffee beans during the roast process. I am thinking that the color change is an indicator of the chemical changes during the roast process. I am an advocate for measuring a “wider spectrum” rather than a narrow wavelength range. The narrow bandwidth of the Agtron is a process result measurement but I do not think it will help me enough to consistently achieve the desired roast and cupping results. I do not know how to isolate the color measurement device from the roast process. I am uncertain whether a “reflected” or “transmitted” measurement would be most sensitive to the color change.

    I am uncertain whether pre-heat the coffee beans improves the final result but I am very interested in cooling the beans after roasting. I have been thinking of variety of methods to have a cooling environment temperature above the dew-point and that will cool the beans quickly. One method I have thought about is a second chamber similar to the roast chamber (swap one of the diagrams above: “pre-heat” swap to roast; “roast” swap to cooling). The cement-mixer within an cooling environment may be convenient to load/unload the roasted coffee beans.

    • January 25, 2010

      You bring up several interesting points. I, too, would like to use a non-contact temp measurement, if possible. Most roasting systems I’ve see use conventional thermocouples or an actual probe thermometer present in the stream of roasting coffee.

      I have also been thinking about real-time colorimetry as a part of the roast monitoring system. Please share your thoughts on this. I’ve been thinking about a sampling system to take samples out of the larger stream of roasting coffee and returning it upon sampling.

      There is also the possibility of using some audio signatures and analyzing the exhaust gas components, as well.

      Keep sending comments as you ponder the topic!

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