The Art and Craft of Coffee (13 page)

Drip average particle size: 600 microns

Automatic drip average particle size: 800 microns in the United States and 580 microns in Europe

Coarse grind average particle size: 1,000 microns

The Turks, who pushed millstones around to grind grain, get credit for inventing the coffee grinder. They used one corrugated plate and one flat plate. One was stationary; the other moved. This system created almost powder-like, very fine grinds. Coarser grinds became popular with more modern brewing methods, as inventors realized the flavor connection between grinding beans to a certain size and the finished coffee’s taste. Other coffee-drinking countries adapted grinds to fit their brewing methods. Today, grinding’s role is straightforward. The finer ground the beans, the more intense flavor they produce and the less time it takes to extract that flavor. This is because with finer ground coffee, hot water touches more surface area during brewing.

A coffee grinder’s only job is to granulize coffee beans into exact and (theoretically) same-sized particles. Some coffee lovers mistakenly think that a range of particle sizes, like a mix of light and dark roasted beans, offers a variety of tastes. Not true! Each brewing method has its own perfect particle size based on how long the particles will touch the grounds. The longer the brew time is, the larger the particles should be. Smaller-than-ideal particles add bitterness due to overextraction. Larger-than-ideal particles underextract, causing weak flavor and waste.

Invest in a good grinder to enjoy the best coffee possible. Get in the habit of grinding just before you brew. This will result in a more pungent aroma and fresher tasting coffee. Plus, some of the best available roasted coffees will open up to you, as some of the characters who roast these precious beans won’t even consider grinding them before shipping. If you home roast, preground coffee is obviously not a consideration.

The Case for Grinding at Home

Industrial rollers produce the most consistent grind possible, making industrial grinding, by far, the best method. It exceeds even the best home machine’s ability to control one of the most important variables: particle size. So why do I recommend grinding at home? It’s freshness. Freshness is an important reason for most coffee lovers because it’s critical for enjoying the kind of coffee aroma and flavor we all want.

Life is a series of tradeoffs; there is just too much coffee character lost in coffee ground after roasting, rather than before brewing. This is not a subtle difference.

Most preground coffees don’t stay fresh for long. Preground canned coffees are purposefully exposed to air after grinding, which removes much of their freshness. This process, called degassing, is done to prevent cans from buckling during their product life.

Beans and preground coffees treated with nitrogen flushing as they are packaged into one-way valve bags stay fresh for about ninety days, much longer than the two weeks of freshness of beans sold in simple fold-over unsealed sacks. One-way bags feature a ringlike indentation with a hole in the center and are clearly visible. Why does this coffee stay longer? Nitrogen flushing minimizes contact with oxygen and protects coffee from elements that hasten staling. However, by design, one-way valves allow carbon dioxide to escape. As the carbon dioxide goes, so do the smells and aromas your taste buds identify with freshness. To date, no coffee packaging method preserves aroma and flavor or allows the coffee to improve over time, as with some wines.

BEWARE OF FRESHNESS DATES

Packaging companies create freshness dates to try to please large coffee companies, which understandably want to build in time to transport and warehouse their products. At best, freshness dates reliably prevent rancidity, but they rarely predict freshness. Seek out packages with actual roast dates (rather than freshness dates) and try to use the product immediately or freeze it within ninety days of the date.

Properly packaged and dated preground coffee also has a ninety-day freshness window, but then goes stale quickly after the package’s seal is broken. Freezing after opening adds additional product life. See the section “Freezing Coffee Beans” on page 43 in
chapter 2
for extensive information about freezing green and roasted beans.

Look for a roasting date rather than a freshness date to determine coffee’s freshness.

Grinding For The Roast

Does roast darkness affect grind? The short answer is yes. Darker roasts need to be ground slightly coarser. A coffee bean’s brittleness increases the longer and darker it roasts and the more moisture driven from it. The increased brittleness causes it to fracture into smaller particles than a lighter roast. This increases the coffee’s bitterness and strength. Consider setting your grinder a notch coarser for dark roasted beans.

Choosing a Grinder

The best grinder is one that consistently produces even-sized particles. Though it seems obvious, determining which grinder does this is not so simple.

Tests called ro-tap tests determine a grinder’s grind consistency. A ro-tap test involves placing a grinder’s resulting grounds atop a series of sieves with different-sized holes and measuring the range and percentages that seep through. One place to look for these test results is my website,
www.coffeecompanion.com
.

Look for mathematical grounds-distribution results from these screen tests. You want the grinder that produces the biggest percentage of identical grounds the ideal size for your brewer. In the section, “Determining the Right Grind for Your Brewer” on page 85, I’ve published the recommended numbers in microns for each grind. Note, the larger the holes in the test screen or sieve, the smaller its screen-size number. For instance, a size twenty sieve has larger screen holes than a size forty sieve.

Blade Grinders

Most inexpensive grinders have spinning blades, hence the name blade grinder. These are notoriously bad for grinding coffee.

FINES: COFFEE GRINDING BAD GUYS

The word “fines” describes 200 to 300 micron-size waste particles produced during grinding. Although all grind specifications allow—and even benefit from—a certain percentage of small fines, any amount beyond 30 percent harms the coffee’s flavor. There are also tinier 100 to 200 micron superfines, which clog filters and add bitterness in virtually any amount to almost any brew. Calling them bitters might be more accurate. You can’t do anything to alter the amount of fines your grinder produces, but you can seek out a grinder with an industry-accepted amount. If you notice coffee clumps in your container of just-ground coffee, exclude these from your brewer.

To use it, pour a premeasured amount of beans into the top, which contains the spinning propeller. As you push a power button, the blades begin to spin, cutting through the beans. The blade’s whirling motion helps create an air vacuum that draws the beans into the propeller’s path.

In practice, this random method often requires shaking the grinder to get any semblance of equal grinding. Even as the grounds get finer and appear more consistent, microscopic examination or a screen test will reveal a wide variance. Also, using a blade grinder causes its tiny motor, located just under the curved metal plate, to heat up the grounds. Many of these grinders come with warnings not to run the motor for more than one minute or risk heat affecting your grounds enough to actually release some taste and aroma.

If you’re not already sold on not using one of these grinders, consider this: They are unpredictable in terms of how fine they grind. One time, it may produce coffee fine for a drip coffee maker. Another time, it may be too coarse or too fine. For espresso, the exact 200 to 250 micron grind particle size for the thirty-second extraction is so critical that you really can’t consider using a blade grinder.

Burr Grinders

Burr grinders, sometimes called disc or mill grinders, are the kind to use. You set the grinder’s range, which then limits size by the distance between the two grinding pieces. Set the gap between the two discs or cones by click stops (stops on your grinder) so you can simply dial your required fineness and assure batch-to-batch consistency.

How does a burr grinder work? A rotating flat metal disc or conical cone fits inside a second, stationary disc or cone. As a chute between the two grinding pieces feeds the beans, flutes that become progressively finer cut them. The coarse surface on one of the discs then grinds them. This design grinds the beans much more consistently than a blade.

Inexpensive blade grinders don’t grind coffee well.

Still, burrs are not perfect. They require careful alignment. They wear down through use and as they do, the grind may drift and become less consistent. Also, some modern marketing touts features such as their timers or the ability of parts of the container to go in the dishwasher. Instead, look for hardened steel discs (what the best grinders use).