The coffee grinder is one of the most crucial pieces of equipment for producing high quality coffee, particularly when making espresso.
How fine the beans are ground influences how quickly the water is extracted, and getting the right extraction rate is key to a delicious cup of coffee.
If the grind is too fine, the extraction will be too slow and pick up bitter tasting oils from the bean, but if it is too fast it will result in coffee that is weak and tasteless.
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So How do you Choose a Good Grinder?
There are three requirements for your grinder. The first is that you need an airtight hopper for your coffee beans, which can then be ground as needed. The coffee should be made within 30-45 seconds of grinding to ensure the freshest taste.
The second requirement is a consistent grind – all commercial coffee grinders have a setting which allows the barista to choose how fine or coarse to make the grind.
This can either be a stepped setting, or a gradual dial. Stepless dials allow the most accurate fine tuning and will, therefore, produce the highest quality results.
The third requirement is how gentle the machine is on the beans. A grinder works by crushing them between two metal plates called burrs, but the grinding process can produce heat which adversely affects the taste, particularly if the machine is in constant use in a busy coffee shop.
Therefore, a larger burr size, which gives more surface area, allows you to grind high quantities of beans without overheating them.
Which is the Best Commercial Coffee Grinder?
The acknowledged heavyweight of the commercial coffee industry is the Mazzer Robur Electronic, currently retailing at $2,495.
This machine is designed for busy coffee shop environments where it will see heavy use. It's one of the larger grinders in the Mazzer range, at 72cm in height and with a footprint of 24 x 31cm. The hopper can hold 1.8kg of beans at a time.
It has a large conical burr set with a larger than average diameter of 71mm, so that even with continual use, the beans are not heated too much while being ground. The reduction in gears means that there is less chance of it seizing up, and it also has a fan which helps keep the machine cool even when run for hours at a time.
The main disadvantage of the burr set is that it needs to be seasoned (or 'purged') by running a large quantity of waste coffee beans through it before it will produce the best results - a new burr set will have slight machining marks which need to be smoothed off by use. However, this is an issue for most commercial coffee machines and is not exclusive to the Mazzer Robur E.
Most coffee grinders for espresso machines have a doser, where a handle is pulled manually by the barista which deposits the coffee in the basket. The Mazzer Robur E is the first doserless model which doesn't cause clumping in the ground coffee as it comes out.
Instead of a doser, the barista can program the machine to produce the correct volume of coffee by adjusting the time. Output for a double shot takes only a few seconds. The display will also count how many shots have been ground during the day.
As with any coffee grinder, the biggest barrier to good quality coffee is making sure the coffee is ground at the right setting. Coffee extracted at the correct rate will produce what is referred to as a 'mouse's tail' – this is espresso at the optimum strength and taste.
People who struggle with electronic gadgets, however, may find the Robur E difficult to use, as both the grind setting and the dosage volume functions are set using a digital menu with an LED display.
But when correctly calibrated, coffee ground using a Robur E machine will produce an espresso with a sweet, aromatic flavor and a fluffy crema, and will do so consistently from day to day.