Grinding Coffee

The fineness of the grounds has a major impact on the brewing process, and matching the consistency of the grind with the brewing method is critical to extracting the optimal amount of flavor from the roasted beans. Brewing methods which expose coffee grounds to heated water for a longer duration of time require a coarser grind than faster brewing methods. Beans which are too finely ground for the brewing method in which they are used will expose too much surface area to the heated water and produce a bitter, harsh, “over-extracted” taste. At the other extreme, an overly coarse grind will produce a weak, watery, under-flavored result.

The rate of deterioration increases when the coffee is ground, as a result of the greater surface area exposed to oxygen. With the rise of coffee as a gourmet beverage, it has become much more popular to grind the beans at home before brewing, and there are many home appliances available which are dedicated to the process.

There are two methods of producing coffee grounds ready for brewing.

Grinding:

Burr based with two revolving elements crushing or “tearing” the bean and with less risk of burning. Burr grinders can be either wheel or conical, with the latter being quieter and having less chance of clogging. Burr grinders “mill” the coffee to a reasonably consistent size, which produces a more even extraction when brewed. Coffee experts consider burr grinders to be the only acceptable way to grind coffee.

Conical Burr Grinders preserve the most aroma and can grind very fine and very consistent. The intricate design of the steel burrs allows a high gear reduction to slow down the grinding speed. The slower the speed, the less heat is imparted to the ground coffee, thus preserving maximum amount of aroma. Because of the wide range of grind settings, these grinders are ideal for all kinds of coffee equipment: Espresso, Drip, Percolators, French Press. The better Conical Burr Grinders can also grind extra fine for the preparation of Turkish coffee. Grinding speed is generally below 500 rpm.

Burr Grinders with disk-type burrs usually grind at a faster speed than conical burr grinders and as a result tend to create a bit more warmth in the coffee. They are the most economical way of getting a consistent grind in a wide range of applications. They are well suited for most home coffee preparation.

Chopping:

Most modern “grinders” actually chop the bean into pieces (and some coffee drinkers merely use a home blender to do the job). Although enjoying a much longer life before wearing out the blades, the results are dramatically less effective in producing a homogeneously ground result and, as a result, will create inconsistent extraction and a degraded product in the cup.

Blade Grinders “smash” the beans with a blade at very high speed (20,000 to 30,000 rpm). The ground coffee has larger and smaller particles and is warmer than ground coffee from burr grinders. Blade grinders create “coffee dust” which can clog up sieves in espresso machines and French presses. These type of grinders are (in theory) only suitable for drip coffee makers though even here the product is inferior as a result. They also can do a great job for grinding spices and herbs. They are not recommended for use with pump espresso machines.

Pounding:

Turkish coffee is produced by infusion with grounds of almost powdery fineness. In the absence of a sufficiently high-quality burr grinder, the only reliable way to achieve this is to pound the beans in a mortar and pestle.