really
Hmm, maybe ask Mr Steve Diedrich, about caffene stability in heat....So far as I know heat esp the low heat coffee is roasted at doesn't affect caffine content. I asked this very question during a roasing class.
see:
Pasted from:
http://www.roastmagazine.com/backissues/janfeb2005/caffeinecontrol.html
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Roast Level
Beyond selection of the green beans, the roaster is commonly thought to control one more variable in the final caffeine content of the beans: the roast level. Popular lore has always been that the darker the roast level, the lower the caffeine content. This is not really the case, as caffeine changes very little during the roasting process. Caffeine has a very stable crystalline structure with a boiling point above 600 degrees Fahrenheit, far above roasting temperatures, which rarely exceed 470 degrees Fahrenheit. This means there is very little change to the caffeine during the roasting process. The minimal amount of caffeine lost during roasting is attributable to sublimation, which is the transition of a substance directly from its solid state to its gaseous state, as commonly occurs with dry ice. Caffeine undergoes this transition at around 350 degrees Fahrenheit. Since coffee is roasted at temperatures above 350 degrees, a minimal amount of the caffeine is lost this way during the roasting process.
Although minimal caffeine is driven off or destroyed in the roasting process, the bean undergoes major changes during roasting. This can confuse the situation because the caffeine content per weight and per volume changes—not because the caffeine changes, but because the size and the weight of the bean changes. Ironically, because the bean loses weight (mostly water) during roasting, the caffeine content by weight increases, but because the bean increases in size during the roasting, the caffeine content by volume decreases.
It is fortunate that there are no requirements to label caffeine content on packages of roasted beans. So many variables contribute to the caffeine content of a single origin at a defined roast level that it is nearly impossible to predict the content without decaffeinating the bean and measuring the amount extracted. Now take differing cultivars from multiple farms and multiple countries, throw in a little robusta for an espresso blend, and you might need to put on another pot of coffee and call an organic chemist.
SPECIAL THANKS to Ted Lingle and Joseph Rivera of the Specialty Coffee Association of America for their contributions to this article and to Gene Spiller, author of Caffeine.
JIM FADDEN is a mechanical engineer and frequent contributor to Roast Magazine.
He can be reached at
jim@roastmagazine.com.
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So, before making any statment do due research....
MY$.02