Guide to Coffee Grinders
A coffee grinder is a must have for anyone who loves coffee, for two simple reasons:
- Control over the coarseness of the grind
To keep coffee as fresh as possible you need to minimise its contact with air. Air is one of coffee's worst enemies as it destroys delicate flavours by turning the natural oils present in coffee rancid.
If you have a coffee grinder at home you can grind your coffee beans as and when you need them. This preserves their freshness, as a whole coffee bean has a much smaller surface area than that of a ground bean and therefore is less exposed to air.
The actual process of grinding releases many of the coffee's aromatics; as you grind you can smell this in the air. If you don't quickly use these grounds then you are going lose this aroma and deprive your cup of valuable flavours. This is another good reason to only grind coffee on demand.
Control over the Coarseness of the Grind
Different coffee makers require a different coarseness of ground coffee. For example: an espresso machine, which has a short brewing time (less than 30 seconds), needs a very fine powder-like grind; whereas a cafetiere, which has a long brewing time (3-4 minutes), needs a much coarser grind.
With your own coffee grinder you get to control the coarseness of the grind as you can adjust the grinder's setting. So if you find that your coffee tastes bitter, a result of over-extraction, then you can adjust the grind to a coarser setting; and if your coffee tastes flat, a result of under-extraction, you can adjust the grind to a finer setting.
Blade Vs Burr Coffee Grinders
Coffee grinders come into two categories:
- Blade Grinders
- Burr Grinders
A blade grinder works in a similar way to a food processor: there is a set of spinning metal blades which roughly cut through the coffee beans. The coarseness of the grind is determined by how long the grinder is left running. Coffee ground by a blade grinder is inconsistent in size as some beans will be sliced through more times then others.
Rather than chopping the coffee beans into tiny pieces, a burr grinder crushes the beans between two pieces of burred metal. A burr grinder produces a much more consistent size of grounds as the coarseness is controlled by how close the two pieces of metal are set to each other: i.e. a smaller distance for fine grounds and a larger distance for coarse. For this reason, burr grinders are far superior to blade grinders.
Why is Consistency Important?
The ultimate aim when making coffee is to extract the maximum amount of flavour whilst leaving behind bitter compounds and caffeine. This is why different coffee makers require a different coarseness of grounds. However, if your grounds are inconsistent then the larger particles in the grounds are going to be under-extracted, leaving behind flavour, and the smaller particles are going to be over-extracted, releasing bitter compounds and further caffeine into the cup. Unfortunately, the two don't balance each other out; instead you have a flat, bitter coffee that will keep you awake for hours.
Choosing a Coffee Grinder
The coffee grinder you choose should depend on for what type of coffee maker you're grinding the coffee. If you're using a cafetiere or a stove-top espresso maker, then a hand grinder is perfectly adequate, although they do require plenty of physical effort to get results.
However, for an espresso machine a good quality burr coffee grinder is essential. As making an espresso is a pretty intense process (its all over in less than 30 seconds) the margin of error for the grind is very slim. This is why you need a grinder which allows for miniscule adjustments to be made so you can get the grind spot on. See 'The Five Elements for Good Espresso' for more information on the importance of the grind.