bigabeano wrote:those are my thoughts exactly. but i'm not so sure about the importance of "aggressive" mixing in a french press or vac pot. any thoughts on its significance, other than perhaps accelerating extraction some?
Hi Scott,
I was looking for a mechanism by which the outgassing of CO2 could make a difference. The only thing I could come up with was that it might vary the surface tension on the coffee grains so as to cause them to wet unevenly. I remembered a piece in Jearl Walker's Amateur Scientist column in Scientific American years ago in which he wrote about Turkish coffee. If you make Turkish coffee in a lab beaker, you can see the sugar melt in the bottom layer. Only when the convection cells take the syrup up to the layer of coffee, in which you can see the grains of coffee surrounded by gas, will the coffee particles wet. When that happens, it suddenly changes the dynamics, and that's what accounts for the appearance of boiling when you do it in an Ibrik. I thought something similar might be happening here, and that if it was that more turbulence might affect it.
I know you did the experiment with a variety of coffees, but I have to imagine that the flavor profile made a difference, since more floral flavors are known to come from smaller and more volatile molecules. We also know from Jim and Abe's visit to George Howell that coffee ground two weeks earlier is only a pale shadow of its fresh-ground self, which puts an upper bound on the optimal time. I imagine that as this is explored, the optimal time will vary with both the brewing method and the coffee itself, and may vary with which part of the flavor profile the person tasting it most values, i.e. I hypothesize that the way a given coffee changes its flavor profile as it ages as whole bean is mirrored as it does so after being ground, only faster, and that the shift from more floral flavors toward more chocolate or wood will appeal to people at different points.
Best,
David
