On the Grind: All About Grinders—Part 1
One of the most essential parts of the coffee brewing process is grinding your coffee beans. Whether you're brewing in a press, pourover, drip brewer, or (especially) pulling espresso shots, having a reliable grinder is extremely important. That said, it's not easy to shop for a grinder, there's a lot that goes into selecting the right one for your kitchen. But we're here to help! We'll be taking a look at what makes these machines tick, and what you should look out for when purchasing. Let's get grinding!
At a basic level, grinders are just motorized devices for making your whole coffee beans fit for brewing. So why not just buy whole bean? Why not grind them at the store? These are great questions.
Beans are at their most flavorful just after grinding, so ideally you'll brew with them within a few hours of having ground them. pre-ground coffee offers less in terms of flavor notes, and generally just produces a standard "coffee" flavor, with strength dependent on dose and roast level. To get at the real flavor notes of specialty coffee, you'll want to grind it fresh.
On top of that, different brew methods require difference grind levels. For pourover coffee, as an example, you typically want a consistency closer to rock salt. By contrast, espresso requires a much finer grind, one that isn't even possible with most coffee grinders.
Blades Vs. Burrs
So you're ready to buy a grinder, but why not just grab a $20 blade grinder at the grocery store? It turns out, for a number of reasons. Blade grinders are simply a pair of blades that spin at high speeds and slice beans to pieces. They are extremely inconsistent, and offer no control over grind level. On top of all that, they have to be replaced frequently as the blades dull.
Burr grinders, on the other hand, provide a great degree of control and consistency. They also tend to last far longer than blade grinders, and can be maintained for years and years with proper cleaning and part replacement.
But what is a burr?
Burr grinders use two plates to grind beans. These plates can be made of a variety of materials, but the most common are steel and ceramic. In the case of most home grinders, the plates will be flat, and sit on top of each other. Some higher end commercial grinders use conical burrs, with a cone shaped burr fitting inside of a funnel shaped burr.
In any case, the burrs will have bumps and nobs that work to grind the beans as they are fed in from a hopper. Typically, a knob can be used to control how far apart the burrs are, thus controlling how fine the grounds are after grinding.
Arguably the most important aspect when purchasing a home grinder is the material and control method for the burrs. We'll discuss control and why it matters next week, but of these two aspects, burr material is the more relevant here.
As noted above, burrs are typically made out of hardened steel or ceramic. There are some very high end coatings, but what you will see in 95% of home grinders (and even commercial) will be steel or ceramic, and each has its pros and cons.
Steel burrs are strong and efficient, but they also tend to dull over time. Because of the nature of burrs, re-sharpening can be a challenge, so after several years the burrs may need to be replaced.
Ceramic burrs generally solve the problem of dulling, and offer highly consistent grinding. They are, of course, more likely to shattering if a bad bean or other debris gets caught within the grinder.
Both materials, however, are completely viable and should last years.