The roasted coffee bean is about two-thirds insoluble cellulose, one-third soluble compounds. Most of these compounds are various organic acids and sugars, which are what give coffee its delicious flavor. The rest are molecules that, when extracted, contribute more astringent and bitter tastes—death to flavor. The sweet spot of extraction is right around the first 19-20% of the coffee’s mass, which tends to provide the best flavor balance. The higher extraction climbs past that 20% mark, the more those astringent and bitter flavors start to assert themselves. Too much less than 19% and the flavor palate starts to taste thin and sour, with little to no balance. With coffee brewing, it really is all about the timing.
So what’s the secret to home-coffee-brewing success? The one item that really separates you from the baristas is a great coffee grinder.
The Science of Extraction—Size Matters
Coffee grounds certainly all look roughly the same size, but in terms of extraction, they aren’t. The problem is that coffee grounds of many sizes reach their extraction sweet spot—that 19-20% —at many different times (millions of different times, if each coffee ground were counted). And so the average grind, containing some finer and some coarser grounds, will extract only a certain percentage correctly; the rest of the brew will be under- or over-extracted. So the only viable solution is to make the grounds as uniform as possible, and this is where a high quality grinder can make all the difference.
There are primarily two kinds of coffee grinders available for home use, a blade grinder and a burr grinder. For those who want their coffee at a professional level, a burr grinder is the clear leader.
The Burr Grinder
Unlike a blade grinder, which has blades that look a bit like a propeller, finely chop the coffee beans into bits, a burr grinder is rather more sophisticated—it consists of two revolving abrasive surfaces (the burrs), between which the coffee beans are ground, a few beans at a time. There are two kinds of burrs—conical and flat—but each produces uniform grounds of coffee, which is the ultimate goal. The automatic burr grinder is descended from the manual coffee grinder, back when it was the only option for the home, which used burrs as well.
While burr grinders are more expensive than blade grinders, some are not significantly so. While a few mediocre performers are available in the $50 range, you can land a very decent burr grinder for about $90 (see below); though as you might expect, there are a variety of precision burr grinders available (at a variety of prices)!
The Baratza Encore strikes a great balance between affordability and luxury—it’s not cheap, but it’s nowhere near the high end of burr grinders. You get what you pay for— a solid, reliable product that should produce grounds uniform enough to help you create an extremely good cup of coffee every morning. (It’s quiet, too.) The Encore retails for $139.
Too expensive? For those in a market below $100, and your best bet may be the Capresso 560.01 Infinity Burr Grinder at right around $90.
On the higher end, check out Baratza’s middle-high-end contribution to the market, the 586 Virtuoso Burr Grinder. Your coffee grounds will thank you.
Special Mention—Old School
Why not use a little elbow grease? As long as you’re not brewing for an army, you might consider a final recommendation—the small-but-mighty manual-style JavaPresse Manual Coffee Grinder retailing for under $25—just the thing for that camping trip where you want to pack light but not compromise the quality of your coffee grind.