Tamp pressure and brew pressure - Page 2

Beginner and pro baristas share tips and tricks for making espresso.
chang00

#11: Post by chang00 »

At risk of being ultra-geeky, this is an article which discusses the effect of brew pressure and espresso:
http://pubs.acs.org/doi/abs/10.1021/jf0206623

Specifically, at 11 atm, the concentrations of 2-methylbutanal, 3-methylbutanal, and 2-ethyl-3,5-dimethylpyrazine are higher. These compounds are generally responsible for bitterness and astringency.

At 7 and 9 atm, methanethiol and propanal concentrations are higher. At 9 atm, these compounds tend to be slightly higher compared with espresso prepared at 7 atm. Methanethiol is responsible for the "freshness" perception, and propanal is correlated with "fruitiness" generally.

rotuts (original poster)

#12: Post by rotuts (original poster) »

Well, How cool is that!

I reading this book I got from my local library by interlibrary loan:

Espresso Coffee: the Science of Quality 2d ed. Ed: Andrea Illy and Rinantonia viani

Check It Out!

many thanks again!

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erics
Supporter ★

#13: Post by erics »

And the technical paper that Henry so geekily referenced :) MAY also be available from your local university technical library - Boston, MA does have its fair share of those. :)

Jim Schulman (another_Jim) referenced this paper in some earlier post and I did manage to get a hard copy from the U of Md chemical engineering library. In addition, if you do a search on "pressure profiling", you'll see where Greg Scace (GregS) mentioned that taste went "downhill" at pressures above 9.0 bar.
Skål,

Eric S.
http://users.rcn.com/erics/
E-mail: erics at rcn dot com