I dont know of any books really. But go out and learn from different people. Thats what I did, make it your quest to ask tons of questions. I will go out purposefully to a shop I find on my gps and just obsearve
you also might wanna check out david schomer's videos. Last time I watched them they were a little behind the times but still had lots of good information. Also Bellisimo's 501 Barista training video has some pretty in depth ideas in it including about 20 min of chemistry from Illy himself.
Definitely check out the Illy book "Espresso Coffee: the science of quality" (you can get the second edition cheaper than the first), and the Coffee Brewing Handbook (available on the SCAA store). These are immensely deep sources of info, the Handbook is more compact and isn't as deep as the Illy book but presents some additional info. These books are the source of quite a bit of the info in the Rao books, and you can follow the sourcing of info even further through the works sited in the Illy book. I think the Illy book is a cornerstone of any good library of coffee info, it is very dense yet broken down well. It gets very sciencey and geeky if you are into that. If you are looking for more botanical info, look into William H. Ukers "All About Coffee", I hear you can get it on the cheap through the iPhone book app.
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