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U of Texas studies coffee bean acoustics


May 22, 2014
By Canadian Pizza

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May 21, 2014, Washington, D.C. – The notion of controlling the roast time and
temperature profile of coffee has prompted an acoustician to explore the potential of using the "cracking"
sounds emitted by coffee beans during the roasting process as the
basis for an automated acoustical roast monitoring technique.

May 21, 2014, Washington, D.C. – The notion of controlling the roast time and
temperature profile of coffee has prompted an acoustician to explore the potential of using the "cracking"
sounds emitted by coffee beans during the roasting process as the
basis for an automated acoustical roast monitoring technique.

Preston S. Wilson
normally focuses on studying underwater acoustics in his role as an
associate professor in the University of Texas at Austin's Cockrell
School of Engineering, says a news release from the university.

These coffee roasting sounds are well known within the coffee
roasting realm, but this is believed to be the first quantitative
assessment of these sounds and the first suggestion to use them in an
automated control process.

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As Wilson reports in the Journal of the Acoustical Society of America – Express Letters, he found three parameters of the crack sound that
could be exploited. Near the end of the roasting process, sounds known
as "first crack" exhibit higher acoustic amplitudes than the "second
crack" sounds that are emitted later. Finally, the rate of cracks in the
second crack chorus is higher than the rate in the first crack chorus.

"The sound of the first crack is similar to popcorn popping, while
the second crack is more akin to the sound of the breakfast cereal Rice
Krispies," explains Wilson in the release.

Initially, Wilson's unfunded project was just to "satisfy his own
interest as a person who roasts coffee," but a commercial application
may emerge for the coffee roasting industry.

An automated acoustical roast monitoring technique "could lead to
optimized coffee roasting, which would increase quality, decrease errors
in roasting, and potentially save energy used to power the roasting
process," he says.

Taking it to the next level and commercializing the process will
"require quite a bit of effort – engineering the design of the sensor
system, the data acquisition and processing," Wilson adds. "It will
require writing software to automatically process the sounds, and then
integrating it into the control system."

Read a summary of the study.