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Date: 19 Oct 2006 21:33:40
From: Alan
Subject: chemical and physical analysis of "crema"?
Although I'm sure we'd all pretty much agree on at least a few points
regarding the production of "crema" (coffee freshness, optimum water
temperature, optimum pressure, etc), has anyone ever done a serious analysis
of "crema" in terms of the physics and chemistry involved? For instance,
while the espresso below certainly differs in appearance form the crema
floating on top, what would a chemical analysis show? Would it show that
the composition of the two is exactly the same, or is one composed of oils,
emulsions, or whatever that are not found in the other? Since crema will
disappear after a while, what is actually happening --- are we just
observing the breaking of bubbles, or are we witnessing the crema
"dissolving" into the coffee? If anyone can point me to a serious analysis
which would answer these and other questions, I'd love to satisfy my
curiosity. Thank you.






 
Date: 20 Oct 2006 14:29:34
From: Barry Jarrett
Subject: Re: chemical and physical analysis of "crema"?

illy has quite a lot in "Espresso: The Chemistry of Coffee"


On Thu, 19 Oct 2006 21:33:40 GMT, "Alan" <in_flagrante@hotmail.com >
wrote:

>Although I'm sure we'd all pretty much agree on at least a few points
>regarding the production of "crema" (coffee freshness, optimum water
>temperature, optimum pressure, etc), has anyone ever done a serious analysis
>of "crema" in terms of the physics and chemistry involved? For instance,
>while the espresso below certainly differs in appearance form the crema
>floating on top, what would a chemical analysis show? Would it show that
>the composition of the two is exactly the same, or is one composed of oils,
>emulsions, or whatever that are not found in the other? Since crema will
>disappear after a while, what is actually happening --- are we just
>observing the breaking of bubbles, or are we witnessing the crema
>"dissolving" into the coffee? If anyone can point me to a serious analysis
>which would answer these and other questions, I'd love to satisfy my
>curiosity. Thank you.
>


 
Date: 19 Oct 2006 15:44:31
From: JulesG
Subject: Re: chemical and physical analysis of "crema"?
This article should answer all your questions about crema. Enjoy !
http://www.coffeegeek.com/opinions/barista/10-14-2006