Coffee Grinders
Posted by Mr Coolerer on 20 Dec 2009 | Tagged as: Technique
A coffee grinder is another often overlooked aspect of coffee making, however it has a massive impact on the quality and taste of your brew, be it espresso or any other method. A grinder is just that, it takes in your whole roast coffee beans and turns them into a powder, some being very coarse, others quite fine. As this step is crucial to the following stages of coffee making, it is important to make sure that the grinder is up to the task, as such it is important to buy a grinder that will do the job properly.
Factors that impact on a grinder to give the perfect grounds for your brew are the ability to adjust the fineness of the grounds, as well as the uniformity of the grain size.
Grinder Adjustability
Brewing coffee involves two time factors, the time the coffee should brew for, and the time it does brew for. In espresso coffee the finer the grind, the more the coffee puck resists the flow of water, taking longer to brew the same amount of espresso. However a grind that is too fine will over extract the soluble components in the coffee. This means that there is only one correct setting for any particular blend. Even small discrepancies will change the quality of your shots. In practice, good baristas will make many small adjustments to ensure that the grind is on target as atmospheric conditions vary. Its supprising how a temperature change of a few degrees can throw off your espresso pours.
Over time baristas have concluded that the optimum timing for espresso is one ounce for single shots, and two for doubles in 25-30 seconds. Adjust your grind to run these times. Varying the preassure of your tamp will compensate to a degree, but these will only take you so far, having an adjustable grinder is the only sure fire way of getting it right every time.
Common household grinders have between 10-20 settings to cover the coarsest grinds all the way to the finest. This is generally insufficent as the espresso range is a very small band, and in grinders with relitavely large increments only 2 or 3 of these will cover that range. A grinder with stepless adjustment or one with at least 40 settings will work just fine.
Grind Quality
If the world was perfect, and our grinders ground our coffee to small particles with every one of them being the same size, then we could set the grind to the perfect size and have perfect coffee every time. But alas the world isn’t perfect and coffee beans are brittle and shatters as the grinder plates hit the bean, producing coffee grounds of varying sizes. This is an issue because the smaller grains tend to be over extracted where as the larger grains are thus underextracted, resulting in imperfect coffee. Even the best contemporary grinders produce grains with a variety of sizes, however this isn’t all bad. A wide distribution of sizes makes a tightly packed puck which allows the water to flow through it in a uniform way without gushing.
The cream of the crop in terms of grinders are the commercial conical burr grinders. These grinders produce elongated grains which pack very well. This method of grinding also produces less fines, the smallest dust-like grind particles. These particles over extract and can affect the quality of the shot. Unfortunatly they’re quite expensive, though they are coming down in price.
Commercial flat burr grinders are nearly as good, although they produce slightly more fines and a little more metallic taste with high grown coffees. However, they’re much more affordable than their conical counterparts.
Finally there are contraptions falsely called burr grinders, available very cheaply that are rubbish. These are not actually burr grinders, they have a series of knobs to crush the beans. This produces a large quality of fines which will cause your shots to be acrid, even with the best beans. In short they are a waste of your beans, not to mention money and time.
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