How coffee is ground is crucial for the brewing process, and different coffee brews require different coffee grinds. It is important to match the consistency of the coffee grind with the coffee brewing method in order to obtain the best cup of coffee.
If you use a coffee-brewing method that exposes the coffee grounds to the heated water for a long time, a coarser ground coffee is best. If you use too fine a coffee grind, this method of brewing results in a harsh-tasting coffee. However, if a coarsly ground coffee is not exposed to the heated water long enough, the resulting coffee will be weak and unsatisfying.
Once coffee has been ground, its flavor begins to deteriorate. The rate of deterioration depends (in part) to the amount of coffee surface-area exposed to air. Obviously, finer coffee grinds expose the most coffee surface-area. The rate at which coffee deterioration proceeds is also heavily dependent on how the ground coffee is stored. This is why coffee should be stored in airtight containers at a cool (but not cold) temperature.
Since the coffee flavor is maximized if the ground coffee is not stored at all, it is becoming more and more popular for the home coffee-drinker to grind the coffee beans immediately before brewing the coffee. There are numerous home coffee grinders now available that allow you to grind your coffee freshly each morning to maximize the flavor.
There are actually three methods of producing coffee grounds for brewing. While we are all familiar with grinding coffee, coffee can also be chopped (e.g., as in a food processor), or it can be pounded into a fine coffee powder in a mortar and pestle.
Pounding is used to produce the coffee powder needed for Turkish coffee. Coffee pounding is best done with a special mortar and pestle. For Turkish coffee, the coffee powder is not removed from the final brew. Therefore the coffee powder must be fine enough to be drunk, although the slurry formed by the coffee powder will sink to the bottom of the cup, and is generally not consumed.
Coffee grinding is burr-based. The burr coffee grinder has two revolving elements - burrs - that crush the coffee bean into coffee grounds. The revolving elements in a burr coffee grinder can either be wheel burrs, or they can be conically-shaped burrs. The conical burr coffee grinders are less likely to clog than the wheel grinders, so the grinding speed can be lower, generally below 500 rpm.
The advantage of a lower coffee-grinding speed is that it produces less heat. Since heat can degrade the quality of the coffee flavor, conical burr coffee grinders preserve the most coffee aroma. Further, if grinding coffee into finer grounds, it is best to do it at a low speed (if possible); again, so as not to heat the coffee grounds.
Many coffee grinders allow high a wide range of gear reduction to slow down the coffee grinding speed, while producing enough torque to prevent clogging for either conical burrs or wheels. These variable-speed coffee grinders are the best choice to grind coffee if the coffee is to be ground for different purposes such as espresso, French pressed coffee, percolated coffee, and drip coffee.
A conical burr coffee grinder can also grind extra fine coffee used for making the Turkish coffee, although most commercial coffee grinders will not grind coffee this fine. This is a deliberate choice on the part of the manufacturer. When the coffee grinder is limited so as not to make Turkish coffee, this ensures that people who do not understand proper coffee grinding do not inadvertently clog their espresso machines by grinding the coffee too finely.
Coffee grinders fitted with wheel burrs generally grind the coffee at a faster speed than the conical coffee grinders, but they are can be a more economical way to get a consistent grind because they take less space. This is why wheel-burr coffee grinders can be best suited for home coffee grinding.
Some coffee grinders are actually coffee choppers, which work like miniature food processors. While coffee grinders like this will chop the coffee beans into coffee grounds, the sizes of the coffee grounds can be inconsistent. This may result in inconsistent extraction of coffee flavor during the brewing process, hence an inferior cup of coffee. Also, a blade coffee grinder (chopper) will inevitably create some coffee dust, which can clog a French press or an espresso machine. These coffee grinders are not recommended.
...written by your friends at The Coffee Brewers