A paper on crema

[James Hoffmann]

For 7 days only:

I have uploaded a paper sent to me by Marino Petracco of illycaffe (it was published for the last ASIC conference I think). I had been e-mailing about why crema isn't destabilised by oil as one would expect. He dodged the question, sent me a paper and tried to get me to attend one of their courses in Trieste.

Anyway - don't say I'm not good to you. Not sure if it is of much use to many of you, but nice to have.

http://s59.yousendit.com/d.aspx?id=08M915W4NNA7T2ZM4J40OTOACW

Enjoy!

[malachi]

Very cool.

Some thoughts:

"The proteins originally present in green coffee beans are strongly degraded, denaturated and chemically modified on roasting by pyrolitic reactions."

- but the starting point varies not only with coffee species but also as a result of processing.

"we based our original method to isolate possible foaming fractions from hot water extracts of defatted ground dark roasted"

- why defatted? why dark roasted?

It's interesting that they found no variance between Arabic and Robusta. Seems to fly in the face of empirical evidence. I'm wondering about the age and the processing of the samples.

"When a more precise determination of the protein content was attempted, remarkable differences were observed in dependence of the method used for assaying protein."

- whoops.

" melanoidins are usually a heterogeneous class of polymers"

- and it seems that melanoidins (along with mannan) are the keys.

[James Hoffmann]

- why defatted? why dark roasted?

I guess that once they didn't want anything to interfere in the foaming process - which fat rather does - when it comes to working out exactly what compounds are playing what roles.
No idea about the dark roasted - and how dark is dark roasted?

- and it seems that melanoidins (along with mannan) are the keys.

This was interesting for me. Most convential writing on foams talks about a foaming agent as if it were solitary. Rarely does anyone mention the role one compound might have in formation and another in stabilisation.

Do you have Sydney Perkowitz's book btw?

[malachi]

"Universal Foam"?
I do not.
My food science library, in general, sucks.