So Tamper Tantrum just uploaded Maxwell's talk on how water affects coffee and it's a real eye-opener. While we wait for his book to come out, I really recommend watching this.

http://www.tampertantrum.com/maxwell-co ... gham-2014/

Very interesting video.

While the book is still a work in progress, the first paper from this collaboration, The Role of Dissolved Cations in Coffee Extraction, has been published and can be found by following the links here.

I'm afraid the quantum chemical analysis is beyond my immediate comprehension, the video was much more accessible for a lay person such as myself.