Man has been cultivating coffee beans and grinding them up for consumption for centuries. The coffee bean is thought to have originated in Ethiopia, in eastern Africa, but it was in nearby Yemen on the Arabian Peninsula that evidence of coffee drinking first appeared in the 15th and 16th Centuries. And where there’s coffee there’s a means of grinding coffee beans not far away.
The first coffee grinders were probably simple mortar and pestle set ups that may not have given a very even grind, but they would nonetheless have crushed the dried and roasted coffee bean into a state that was capable of being brewed in hot water. Nowadays there are a plethora of electric and hand coffee grinders that can deliver coffee powder in varying degrees of fineness with varying degrees of effort (zero for the electric models, whereas some of the manual devices need a bit of elbow grease).
Going for an electric coffee grinder would make sense if you always drink your coffee at the same location as the grinder. We like to travel and we like to drink coffee and the only way we can do both is to take the AeroPress and a hand grinder with us.
Want to buy a grinder? Check out our favourite Porlex Mini and Tall Grinders.
Why Grind Coffee?
If you put coffee beans in hot water and boil them for long enough you will get an astringent, bitter brew that may be recognisable as coffee, but not something you would want to drink regularly. However, grind those same coffee beans (well, not the actual ones you boiled, fresh ones) and filter hot water through the resulting coffee grounds and you are on the right track.
Grinding coffee beans exposes all the flavour compounds and oils (solubles) that are locked inside that hard ol’ bean. By grinding the coffee beans and creating the grounds you are, in effect, increasing the surface area of the pulp of the bean which means the water (a universal solvent and the basis of all life on earth) has access to the maximum amount of these solubles from which to extract flavour.
Ground Coffee vs Instant Coffee
The flavour compounds and oils inside a coffee bean are delicate, fragile little things. They are safe and stable while they remain inside the hard bean casing, but break open the bean and expose the solubles to the air and bad things start to happen. They start oxidising (chemically reacting with the molecules in the air) which means the delicate flavour and aroma compounds literally start to disappear.
At least 50% of coffee aromas are lost within 15 minutes of grinding.
Coffee grounds are susceptible to taste and aroma contamination, they tend to absorb water when in humid air which dilutes the solubles, plus, a very high percentage of CO2 (which is created during the roasting process and is key to extracting oils in the plunging process) is lost into the atmosphere.
Even with all the technology thrown at Instant Coffee to try to keep it fresh, there is simply no way it can replicate the true flavours and aromas of a freshly ground coffee.
Types of Coffee Grinders
You will find two types of coffee grinders on the market – blade grinders and burr grinders. As a general rule blade grinders are less expensive than burr grinders, however that’s about the only thing they have going in their favour.
- Blade Grinders: The name should give us a clue as to the effectiveness of these types of grinders. Can you grind something with a blade? Not really. You can cut things with a blade, and tear things if the blade is moving fast enough and is blunt enough. But you can’t really grind anything.The coffee grounds you get from a blade grinder will be inconsistent in texture and probably too fine (powdery) or too course for your coffee maker. Blade Grinders can also burn the coffee because of the heat created by the whirling blades. Not great.
- Burr Grinders: The classic old hand coffee grinders (often ornately
engraved and made from brass) are great examples of burr grinders. The burrs take the place of blades and these are typically round discs or cones (known as flat or conical burr grinders). Burrs have lots of sharp edges from the grooves that are cut into them and when they are rotated against each other (or one burr rotated while the other is kept stationary) the coffee beans are ground up between them.
Adjusting the gap between the burrs is how you adjust the coarseness of the coffee grounds.
Burr grinders can be hand operated or electrical. Hand grinding enough coffee for one shot will probably take you a minute or more (keep going until you can’t feel any lumps) while an electric burr grinder will deliver coffee grounds in a few seconds. A hand grinder doesn’t break down though, and you don’t need power. Perfect.
Getting the Right Coffee Grounds
You have bought yourself an AeroPress coffee making machine, a grinder and a bag of your favourite arabica beans. Time for a cup of coffee, right? Not quite. You now need to grind up the beans to produce the coffee grounds. This is a straight forward process, and can be overlooked because of that, but it does require some thought.
The main thing to consider is how fine or coarse you want the coffee grounds to be. It can make the difference between an okay coffee and a brilliant one.
Things that influence how you should grind up the coffee beans include the:
- Coffee Maker. An AeroPress can handle anything from very coarse to fine coffee grounds (every grind size except extra fine) so you are pretty safe with this machine. A french press, percolator and even a drip coffee maker with a cone filter will not handle fine ground coffee very well. You will need to adjust your grinder to Medium or even Course grind. Read your coffee makers instructions to get the recommended ground size.
- Type of Coffee. This gets a little bit technical and is perhaps best left to the aficionados, but just so you know…
- coffee beans that are heavily roasted will be dry and brittle compared to medium or low roasted beans
- coffee beans grown at a higher altitude (or cooler areas more generally) will have a longer growing season than those grown at lower altitudes (warmer climates) and will be denser because of this
- older coffee beans with be drier and more brittle than younger coffee beans
- Arabica vs Robusta. Yes, they grind a bit differently so see if you notice a difference when you swap varieties
- Brewing Time. The AeroPress has a very short brew time which is ideal for fine coffee ground (gets all the flavour solubles without over extracting bitterness). However other coffee makers require longer brewing times and you will need coarser coffee ground for these machines. Read the makers instructions for recommended grind levels.
- Extra Coarse. Very distinct particles. Even chunkier than instant coffee. Uniformly large bits. A fine potting mix perhaps?
- Coarse. Distinct particles. Looks similar to instant coffee (go on, you’ve got a bottle of it in the cupboard).
- Medium. Some coarse bits but finer particles than instant coffee. More like coarse sand that doesn’t stick together well.
- Fine. A finer sand that sticks together when wet. Like sugar particles except not as hard.
- Extra Fine. Not quite a powder but just about. Very fine sand perhaps. Feels powdery with a bit of grit.
Ultimately, it’s fun to play around with different coffees and different grind settings to see which you prefer most.
Now that you’re effectively an expert on grinding coffee, head over here to check out some equipment that’ll help you put your new skills into practice.