Mr @OhYmerej, you asked for it, and now you got it.
First of all, every piece of information comes from this site because I neither possess the knowledge wizardry of this info nor the expensive, expensive technology needed to take part in the wizardry.
One day Jeremy wondered….”where does the 18-22% rule come from mike?”
The only thing that I knew at the time was that in regards to girls, the 18-22 rule not only rocks, it is also very, very legal (eat that statutory….). As to how it relates to coffee….I didn’t really know. So I took to my friend google and searched….
To summarize, the 18-22% extraction means the percentage of solubles that are extracted out of the beans. Extract too little and you get underdeveloped flavour (typically a sour or green taste). Extract too much and you get overextracted (or bitter) tasting coffee.
Who do these figure pertain to?
The average American coffee palate ~1960s taken by survey.
Brew strength is also important and can be measured by TDS, total dissolved solids which in the same study is determined to be 1.15-1.35%.
How much does all this matter? I dunno, I wish I could just experiment all day with all of those expensive equipments but unfortunately I’m not enough of a coffee celebrity to have that opportunity. All I know is that the coffee that is being served by me on the Slayer on Saturdays probably do not adhere to those rules. I still think that coffee does taste good outside those parameters and probably has something to do with the way that coffee technology has changed. (More about the Slayer/pressure profiling experience will be discussed in the upcoming week)