Hi Andy,AndyS wrote:David, if I understand you correctly, you're NOT saying that the gicleur produced the bitterness, but that the on-off-on preinfusion cycle produced the bitterness. Yes?
Any further thoughts on how the gicleur affected things?
Without the gicleur, the preinfusion seemed necessary to reduce the frequency of channeling if I wasn't quite careful. With it, and the resultant longer dwell times, the preinfusion causes the bitterness. That may be due to the fines getting a chance to overextract before the pressure migrates them into a cake or out of the basket altogether; I also seem to get a similar bitter edge if I rap the portafilter to settle the grounds before tamping, suggesting again that at least with my machine and grinder I'm generating fines that are best moved out of the way. The gicleur seems a definite plus on this machine for lots of practical reasons, and the espresso seems to me to be a bit smoother as well. As you know, when you change one thing, it often means altering other parts of the system or practice to get the most out of it before you can judge whether it's helped or not. This is the sort of thing that makes science so hard for people who attempt to actually learn something from it.