Coffee – Picking The Perfect Grinder
Coffee beans, like any food product, oxidize when exposed to air. The grounds, since they have a much larger relative surface area than the bean, and no covering, suffer this effect even more. Grinding beans at home produces the least exposure to air and the freshest grounds. And you can grind only what you immediately need.
But nothing is without its price. Grinding is time consuming and messy, so if you choose to invest the effort to reap the reward, pick the best you can afford.
Grinders fall into three broad categories – burr, blade and crusher.
The third type is some kind of mashing device, often an ancient-style mortar and pestle. These crush the beans, which is difficult and produces a very uneven sized granule. Not recommended where you have a choice.
The blade grinders don’t actually grind at all, they chop. A whirling blade slices the beans into smaller and smaller sections until they approach something like a small grain. Unfortunately, the grains are invariably too large and of inconsistent size.
As a consequence the surface areas of the granules vary, releasing varying amounts of flavor oils when brewed. Another effect of slicing is often the production of excess heat, as a result of the high speed of the blades. That friction warms the grounds and partially dissipates the aroma.
The first type is the first choice. Burr grinders have a pair of motor driven plates with pyramid-shaped teeth that grind the beans to a consistent, small-but-not-too-small granule. The better models allow adjusting the size of the grain and the speed of the grinding.
Adjusting the size is important in order to ‘fine tune’ the grounds to allow just the desired brew. Controlling the speed keeps the warming effect to a minimum.
Even burr grinders fall into two classes – the conical burr grinder is preferred by real coffee aficionados. Though noisier, they allow the most control of grain size and speed.
Good conical burr grinders can rotate as slowly as 500rpm. By contrast other burr grinders spin at 10,000rpm or higher, blades between 20-30,000rpm. That allows very fine control and little heat. The fine grind is especially important for Turkish-style brews. Some grinders have a continuous dial, others have a series of up to 40 steps to adjust the granule size.
Beyond those broad attributes, the home barista will want to look for solid construction, ease of cleaning and low noise. A cleaning brush and removable upper burrs is essential. Different materials used can also affect how much static electricity is produced – that causes the grains to stick to the burrs and container.
A timer switch and auto-shutoff is a nice addition and being able to see the beans as well as the grounds is helpful for judging the results in the grinder. Dark plastic or glass may be aesthetically appealing but it obscures the view. Grounds can change color slightly depending on the fineness.
Read reviews and be prepared to spend a little more and you’ll be rewarded with the freshest, most flavorful cup.