We bought a micrometer (accurate to 1 micron) and microscope last week to get a better handle on our particle size situation. The micrometer can tell us about the maximum particle size in our chocolate and is very fast and easy to use. The limitation, though, is that it cant tell you anything about your particle size distribution. Thats where the microscope comes in. We wont be able to do anything with the microscope this weekend (no slides), but we did run tests on a half dozen of our bars tonight using the micrometer.
Very interesting results, and very much in line with what Ben, Clay and many others have previously stated stone melanguers are fully capable of producing very fine/refined chocolate. One of our older batches that was in the melangeur for 60+ hours had a maximum particle size of six microns. Our more recent batches where we had opted for a lighter conche (and because its all done in the same process, less refining) our maximum particle size ranged from about 25-35 microns for most batches, but up to as high as 40 microns for one origin. Mystery (if there ever was one) solved with regard to the grittiness.
Over the next couple of months well be running some tests and measuring particle size as a function of (a) time in the melangeur, and (b) batch size. Larger batch sizes means that any given particle will spend less time between the wheels and the base, which should translate into larger particle sizes at any given time. That being said, there are several possibilities for controlling particle size and total time in the pot. Were also going to test the effect of running the melangeur as a conch (no refining) by separating the wheels from the base can we conche in a Santha without further refining?
Next week, once we get the microscope slides, well be doing our first measurements on particle size distribution. Its a fairly tedious process from what we understand, but will give us a really valuable set of baseline data to work with and compare to when we make any future process changes.
David and Leslie