HomeRoast Digest


Topic: My coffee cooling data (4 msgs / 79 lines)
1) From: Ken Mary
I hope you can see the attachments. They may also be displayed below the 
body of the message, so scroll down.
The "bean cooling" graph is data from eight "survey" roasts. The curves are
labeled with the cooling method and spice rating, 1 is lowest and 5 highest.
Spice is a desirable flavor character that stands out in my ability to
taste. pp is a popcorn pumper with different airflows, WBI is a Poppery
cooled at an intermediate airflow, tray is a cookie sheet with no airflow.
Temp of the top layer of beans is measured by handheld IR. The curves are
not profiled, but represent natural cooling at fixed airflow.
The "best spice" graph is a slice through the cooling curves at 230F vs
spice rating. As you can see, there is a clear maximum at about 1.5 minutes.
I am surprised at such clear evidence of an optimum cooling rate, even
across different roasters, different cooling methods, and different coffees.
I will probably not run any special studies, but will fully document the
cooling in my normal coffee roasting to find the optimum for each roaster
and bean. There could be a cooling profile better than the natural curve,
and this could be done by modulating airflow.
--

2) From: Dan Bollinger
Ken,  Nice work!  Would you do me a favor?  First, did you blind taste these
or did you know which profile you were tasting?  Second, would you label the
scatter plot on the second image with the series name from the first?
thanks, Dan
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are
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highest.
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minutes.
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coffees.
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3) From: Ken Mary
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No blind tasting was done, the degree of spiciness is easily ranked in my
mind. The slice represented by the best spice plot is a horizontal line
through 230F, the data points are the intersection of each consecutive curve
left to right with the 230F line. Any other line that intersects all the
curves of a particular method will yield a similar graph. At 230F all the
methods "line up" to make the best looking bell curve. Toss out the two
points 5, and 4 (at 2.4 min) so that all remaining points are from the
popcorn pumper and the best spice curve does not change significantly.
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4) From: miKe mcKoffee
From: "Ken Mary" 
 The "best spice" graph is a slice through the cooling curves at 230F
vs
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minutes.
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coffees.
Interesting. It's hard to know exactly what you're tasting and mean by
*spice* and it really doesn't matter. I think I know or have an idea.
Regardless it's a taste *you* are after and that's what counts in your
roasting! It's also interesting (to me:-) that 1.5min to 210-230 happens to
be cooling rate I've been using boosting the Rosto fan to 130v.
MM;-)
FrankenFormer Rosto Roastin' - Royally Balance Brewin'
Rocky grindin' - Miss Silvia brewin' too!
PNW HomeRoast List Gathering Info' URLhttp://home.attbi.com/~mdmint/coffee/pnwhrg.htm


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