MARGINAL GAINS - EXTRACTION: NOMENCLATURE AND CONTEXT.
Extraction is still big news in coffee, has been for the past 50 years, don't see a reason for it to stop any time soon. But we really need to think about how we talk about it.
23.24
What does that mean?
23.24% extraction
Any better?
Nope, not really.
See context is everything, I'm not just talking about the recipe or the coffee used or the grinder, water etc.... It's no single one of those things, it’s all them coupled with an impractical and flawed search for the maximum.
Maximum extraction is where the nomenclature part of this post comes to the fore, because we don't really mean maximum extraction we mean maximum desirable extraction, or to put it another way our optimum extraction. These two things are not the same.
How can we be so sure?
Remember the Power Rankings? Our maximum extraction was set by one thing only, our coffee. It was the total amount of solubles we could extract, a hard limit using the methods at our disposal and set at 27-30%. That's everything we can extract, desirable and otherwise, so our optimum must be lower than that.
Optimum Extraction 23.24%
Better? we're getting there, but there is still information missing.
That number tells me that the brewer decided that beyond this point undesirable flavours became noticeable or prominent. What it doesn't tell me is what 23.24% that is out of our total. What is the make up of that extraction? Do we really believe that for any given set of samples of the same % they are all created equal?
This, for me, is the next big leap in understanding in brewing chemistry. Work is already under way. I know of situations where the water mineral make-up has pushed extraction down yet increased desirable flavour. People are working on extraction rates of individual grind sizes to better understand how we reach our overall average extraction that our TDS meters measure. Grinder innovation continues with variable rpm and new ways of looking at and analysis particle distribution.
In short, it's not about the number. It’s about the context behind that number and how we communicate it.