I think many of us agree that one of the most important utensils for the preparation of espresso is the
Many baristas account the grinder to be even more important than the espresso machine, because ,errors which are caused during grinding cannot be compensated with machines employing the most sophisticated technology.
Therefore, the grinder and the grinding process should be given the maximum attention during the preparation of espresso and so do the burrs.
Bluecold wrote: It would appear that Mahlkoenig knows stuff about burrs that Italmill and Mazzer do not. It also appears that the added R&D expense and added manufacturing precision do not offer any real benefit over just using bigger burrs.
The quality of MK burrs are another world. I have to admit that I am not a big fan of Mahlkönig but they produce their own burrs under a high quality management on eroding and milling machines.
I cannot say if their R&D expense is much higher than Mazzer's at least MK is much more transparent with showing their results and they have to if they want to keep their progressive sponsor monopoly.
Important for the fine degree of grinding setting for espresso is the correct
distribution of particle sizes, i.e. the different sizes of the ground coffee bean
particles, also known in the trade as "particle size distribution". For the
preparation of espresso it is important that the ground coffee is not
homogeneous, but rather contains different particle sizes. An ideal
distribution contains a certain number of the smallest dust-sized, medium,
and coarser particles. From this distribution an average value is calculated,
the so-called median, which is important for the extraction. Particularly
relevant are the smallest dust particles, also known as "ultra-fines", which lie
in the size range of 20 μm. As rule of thumb the following can be noted: the
more pressure required for the preparation, the more ultra fines the ground
stock should contain. These fine particles settle between the larger particles,
close gaps and thus consolidate the coffee "cake" through which the water is
pressed. Ideally, the median sizes for espresso range between 200-240 μm.
It is only within this size range that the grains can lie together optimally with
later tamping (pressing together). Compaction of the ground coffee in the
portafilter through even tamping and the smoothing of the surface are
particularly important for the infusion process.