Degrees of Coffee Grind

Degrees of Coffee Grind

Commercial coffee grinds vary from brand to brand. Coffee companies set and monitor coffee grinds by using mesh sieves stacked in a series with the coarsest mesh at the top. The level at which the particles of a grind stop falling, as well as the percentage of particles arrested in other sieves of the stacks, gauges not only the basic degree of grind, but also indicates the uniformity of particle size. If, for example, a coffee company wanted to check its medium-grind coffee, intended for a percolator, it would expect that a high percentage of particles from a sample of ground coffee would stop at Gauge 9. If too many particles were to fall too far, or perhaps never even drop through to the Gauge 9 sieve, the company would know that the grind was faulty, and that the grinder might need re-calibrating.

Also, beans grind differently depending on the degree of roast. For example, darker-roasted beans become more brittle with moisture loss and are more prone to break into various sized pieces and powder. The grinder might need some adjustment in order to produce the same degree of grind as that obtained with a different roast.

An excellent way to determine the correct degree of grind to suit the brewing method, is to obtain a small sample of commercially ground coffee. Rubbed between thumb and forefinger, the degree of grind is relatively easy to judge. Commercial grinds are specifically designated as Turkish, espresso, filter fine, and medium grinds. Grinds coarser than medium are practically non-existent commercially. They are generally used only in a jug brewing, and are not very economical, since the same amount of beans ground coarsely produces less volume, less extraction and therefore less flavor than if it were ground finer.

In recent years, certain coffee companies have attempted to gain a larger share of the market by producing in-between grinds, promising consumers of filter and cafetiere coffee alike that the same "omnigrind" works for both. Another grind (which defies the laws of physics) is one that supposedly satisfies the requirements of both filter and espresso machines. Not only does the production of such grinds result in the wrong extraction in one or the other of the brewing methods, it also confuses people who want to understand why coffee is ground to different degrees.

One good result of the "omnigrind" for machines requiring a fine or a medium-ground coffee, is that it provides the perfect alternative grind for the Neapolitan flip machine and the Cona vacuum machine. Both of these methods of brewing benefit from the greater extraction rate of a near-filter grind, and the fact that the very slightly larger particles of the "omnigrind" are not as prone to fall into the coffee liquid because of the machine design. One tip for espresso perfectionists; in Italy, to maintain the production of a perfect espresso, the barman (barista) will alter his grinder to produce a very slightly coarser grind on a day of high humidity.

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