The whole purpose behind grinding, or milling coffee beans, is to speed up the coffee brewing process. Simply soaking whole coffee beans in water will eventually yield the familiar brewed coffee beverage, but the amount of time required would result in cold coffee. Grinding the beans allows the hot water to touch more of the surface area during brewing, resulting in a more intensely flavored beverage, produced in less time.
TYPES OF COFFEE GRINDS
The ideal grind is one in which the particles are a uniform size, and the ideal fineness of the grind depends on the length of the brewing process to be used. The longer the brew time, the larger (or coarser) the coffee grounds should be. Beans ground too fine will result in bitter brewed coffee. Conversely, too coarse a grind for the brew time will result in weak coffee.
For drip coffee makers used at home with flat-bottomed filters, a medium (the texture of sand) grind is best. For drip coffee makers used at home with cone-shaped filters and pour over devices, a medium/fine or fine grind (a texture somewhere between sand and salt) works best. Stove top espresso pots yield the best results using coffee of a fine grind. And finally, espresso machines require a superfine grind (a texture between salt and flour).
Dark-roasted beans are more brittle because the increased roasting time forces more moisture from the bean. Grinding darker beans may require a setting for a coarser grind, as they will fracture into a finer grind naturally due to their natural brittleness.
TYPES OF COFFEE GRINDERS
MORTAR AND PESTLE
A mortar and pestle can be used to pound, or pulverize, coffee beans to a consistency similar to flour. This fine grind is typically used when using the Turkish method of brewing unfiltered coffee.
Blade grinders use blades spinning at a high rate of speed to chop the beans. Blade grinders tend to be less costly than burr grinders, but there are several disadvantages of blade grinders, such as less consistency of particle size and extremely small particles that can clog sieves in espresso machines. As such, blade grinders should be used to grind coffee only for drip coffee makers.
Blade grinders can also result in premature heating of the coffee grounds, due to the friction of the blades and heat from the motor. This heat damage is minimal, however, if you are only grinding enough coffee for a few brew cups, as the grind time is just a few short seconds.
Burr grinders, also known as mill or disc grinders, use either a pair of cones or a pair of discs. In either case, one of the elements is stationary, and the other rotates. The beans are crushed between the two elements, releasing the bean’s oils. Burr grinders grind coffee to particles to a fairly uniform size, resulting in a richer and smoother brew.
Roller grinders grind beans between pairs of corrugated rollers. Roller grinders produce the most uniformly sized particles, and result in less heating of the coffee beans. However, the cost and size of roller grinders limits their use to almost exclusively commercial and industrial coffee roasters.
We’d love to hear from you – do you grind your own beans at home? What type of grinder do you use? Any special tips or tricks you’ve learned to improve your home cup?