Grinding Coffee

Grinding coffee is the process of physically breaking down coffee by crushing or cutting the roasted coffee beans into small particles to facilitate an optimal extraction of the coffee’s flavor components including both the inorganic as well as the organic materials that, when the coffee is brewing, create the coffee’s overall flavor and aroma characteristics.

Proper Grinding Key to High Quality Brewed Coffee

Proper grinding is essential to ensure a high quality cup of brewed coffee. Insufficient grinding produces a weak and flavorless coffee, while excessive grinding causes staling (oxidation).

Choosing a Coffee Grinder – Burr Coffee Grinders

Burr coffee grinders are recommended over blade coffee grinders as they produce a more consistent grind size and avoid overheating (e.g., re-roasting) the coffee beans creating an off-taste.

A burr coffee grinder uses a burr to crush the whole coffee beans between a stationary surface and a moving grinding wheel. Wheel burr grinders use a high speed rotation while conical burr grinders use a slower rotation and are more expensive.

Conical Burr Grinders are the recommended coffee grinders because they are less noisy and messy than wheel burr grinders, and are also better at handling oily or flavored coffees without clogging.

Blade Coffee Grinders

Blade Coffee Grinders use propeller-like metal blades to chop up (smash) the whole coffee beans.  The grind size varies from fine to coarse, and this is controlled by how long you continue to run the coffee grinder.

Problems with Blade Coffee Grinders

A criticism of blade coffee grinders is that they produce an uneven grind size (e.g., larger and smaller particles), which leads to inconsistency in brewing. The blades also produce coffee dust that may clog the sieve in an espresso machine or a French Press.

Excess heat may be generated when coffee is ground very fine using a blade coffee grinder, and this may essentially re-roast the coffee beans and impart a burned taste to the coffee.

Determining the Coffee Grind Size

Coffee grind sizes vary from fine to coarse, and this is generally controlled by how long you continue to run the coffee grinder. The coffee grind size for a particular beverage depends upon several factors including the type of coffee brewer or espresso maker being used.

Generally a course grind size is used in the French Press coffee brewing method. Coffee beans used for making espresso are usually given a Dark Roast (e.g., Espresso Roast) and the grind size is typically very fine, producing a concentrated coffee beverage.

Determining Grind Size Based On Espresso Machine Type

The grind size for a steam-driven espresso machine should be finer than for a pump-driven espresso machine because the steam-driven machine doesn’t have as much pressure to push the water through the coffee grinds.

Finer Points of Choosing Coffee Grind Size

More subtle factors in determining a grind size to produce a high quality espresso include the current temperature and humidity, which might cause a variation requiring adjustments. Ultimately the barista must choose the optimal grind size for the particular brewing coffee or espresso in order to achieve the desired flavor.

Premium Gourmet Coffee and Ultimate Espresso Brewing Tips

For a bevy of tips on brewing the perfect cup of gourmet coffee make sure to see our section on Coffee Brewing. You can also read detailed coffee flavor profiles of Gourmet Coffees and instructions on preparing Espresso Drink Recipes.

If you are an aspiring barista then check out Pulling A Perfect Espresso Shot as well as Barista Guide to Perfect Lattes and Cappuccinos.

For detailed definitions of coffee and espresso terminology including tasting terms, espresso machine parts and more, see the Coffee and Espresso Glossary.  For a detailed history of the revered coffee bean make sure to check out the World’s Best History of Coffee.