I've been scouring the net to try and find real data about what is extracted, over time, from an espresso shot, presented in a simple and useful format.
What I'm really trying to do is to figure out if at rough timing intervals, there is something meaningful I can say about what's coming out of the pf at that moment. Many people don't know that caffeine is not very soluble, for instance, and another common unknown factoid among amateurs is that bitter tannins really rise quickly after 30 seconds.
This chart is pretty famous:
and I found this one today:
Are these two charts based on real data? Can anyone find a ref to the data?
What does it mean in these charts for intensity to be 100% and then drop down? Wouldn't each of the 4 categories go to 100% and stay there?
I read these charts to be giving me "extraction percentage rate of this group per second", but that's just my trying to make sense of it.
Of course, there is this famous chart of Illy's:
but it's not really that helpful when making a shot as it doesn't talk about caffeine or bitterness.