Too many coffee enthusiasts are choosing the wrong grinder because either its a tool they’re already familiar with, or because certain products appear more cost effective. However, your choice of grinder matters when it comes to optimizing the flavor of specialty beans. Blade grinders chop beans inconsistently, leaving you with with both pulverized and coarse chunks of coffee bean. This leads to uneven flavor extraction, as various particle sizes require different brewing times.
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Use two revolving abrasive wheels (less expensive) or conical (the very best and most expensive) grinding pieces to crush the beans with minimal frictional heating. During grinding, this process allows more natural oil to be released from the bean due to the crushing and squeezing, producing a smoother and richer cup of coffee. These mills (available as electric and manual models) produce a uniform grind which can be adjusted depending on which type of coffee is being brewed. The even grind also reduces the amount of fine particles that can clog filters. The burr grinders are able to grind a wide variety of particle size save the extremely fine grind used in the preparation of Turkish coffee.
A method using high speed rotating blades wither in one made specifically for coffee and spices, or in a regular food processor. These are more inexpensive compared to burr grinders, but the grind is somewhat inconsistent, and produces a copious amount of coffee dust which can clog French press filters and pump espresso machines. Another drawback is that it’s only effective for small batches as the method produces friction which warms up the coffee beans, producing a less flavorful cup.
Turkish and Arabic coffee styles require a grind that is so fine it resembles powder. Burr grinders cannot achieve such a tiny particle size, so pounding the beans with a mortar and pestle can pulverize the coffee finely enough.
During the Roller Grinding Process
Beans are ground between pairs of corrugated rollers. A roller grinder produces an even grind and prevents the ground coffee from becoming heated during the process. However, due to size and cost, roller grinders are used exclusively by industrial coffee producers, often relying on water-cooled models for the commercial production of Turkish coffee and espresso.