Last Updated: 6th July 2021
A coffee grinder is an absolute must-have for any coffee lover. Out of all the factors which affect taste when brewing coffee, it’s the grind which has the greatest influence. This is for two important reasons: grinders help keep coffee fresh, and give you the ability to adjust coarseness.
The key to good coffee, as with good food, is fresh ingredients. Coffee beans are relatively volatile and will lose flavour as they age. To keep them as fresh as possible it’s important to minimise their contact with air.
So what does this have to do with coffee grinders? Well, when you grind a bean you’re exponentially increasing its surface area, leaving it extremely vulnerable to air. Once coffee is ground, bright and acidic flavours quickly disappear. Within as little as 15 minutes much of this flavour is lost forever. This is why: to get the most out of your coffee you should always grind it immediately before use. Unfortunately, coffee brought pre-ground, no matter how well it’s packaged, will have already lost some of its flavour.
Different coffee makers require a different coarseness of ground coffee, which is usually dependant on how long the brewing process is. 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 longer brewing time (3-5 minutes), needs a much coarser grind.
Manufacturers of pre-ground coffee usually adopt a one-grind fits all strategy. They supply all their coffee with the same medium grind, what has been coined the omni-grind, and expect their customers to adapt their brewing methods accordingly.
With your own coffee grinder you’re in control over the coarseness of the grind. So if you find the coffee is not quite to your taste you can easily adjust it ready for next time. If it tasted bitter, a result of over-extraction, you can change the grinder to a coarser setting; and if your coffee tasted flat, a result of under-extraction, you can change it to a finer setting.
The first consideration when choosing a grinder is usage. What type of coffee maker will you be grinding your coffee for? Espresso machines and cafetieres are at either end of the grind size spectrum, espresso being fine and cafetiere coarse; and some grinders will struggle to reach either end (or both ends) of this spectrum. So first ensure that any potential grinder is capable of grinding for your needs. If you’re planning on using your new grinder for several different coffee makers, then you’re better off going with a stepped grinder (more on this below).
The next consideration is price. There’s a huge variance in price between coffee grinders, and as a general rule you get what you pay for. If you have a tight budget then you’re better off opting for a hand grinder rather than a cheap electrical grinder (sub £60) as cheap electrical grinders tend to be unreliable and produce inconsistent results – that’s as long as you don’t mind using a bit of elbow grease to grind your coffee.
The vast majority of electrical grinders priced over £150 are designed for use with an espresso machine. Whilst most of these espresso grinders are capable of grinding for other coffee makers, they tend to be less consistent on coarser settings.
The last consideration is size. If your partner or housemate doesn’t share your love for coffee they may object to you taking over the kitchen with a large grinder. Most commercial grade grinders (£450+) are designed for the café setting and are too tall to sit on a kitchen worktop directly below a cupboard.
Blade grinders are very similar to a food processor. They have a whirling blade which hacks through the coffee beans as they bounce around inside it. The problem with blade grinders is that it’s impossible to control the coarseness of the grind. The blade works randomly, cutting some beans into tiny pieces, while others remain relatively unscathed. This inconsistency causes problems when brewing, as the tiny particles will over-extract whilst the large particles will under-extract. Unfortunately, the two don’t counteract each other to make something tasty; it’s not that simple!
Burr grinders on the other hand work in a completely different way. The grinding mechanism consists of two discs/burrs) one stationary and one rotating, between which the beans are crushed. To control the grind size the discs are set slightly apart with the grounds only able to pass through the discs by fitting through this gap. If they are too large they continue to be crushed until they can pass through. The size of the gap between the discs is controlled by the settings on the grinder. If you change to a finer setting, the gap between the discs will shrink, and with a coarser setting the gap will grow.
Burr grinders can still be unpredictable. There’s nothing to stop finer particles passing though the gap between the burrs, so the grind setting essentially only controls the maximum size of the grounds. However, having said this, they’re still head and shoulders above blade grinders.
The discs on burr grinders come in two different designs: flat burr and conical burr. It’s often said that the two different shapes influence the flavour profile in the resulting coffee. Flat burrs are thought to highlight the sweeter notes, such as chocolate, vanilla and caramel; whereas conical burrs are thought to highlight the brighter floral and fruity notes. However, this has not been substantiated; there’s no evidence (well at least not publically available) to support it, and so we recommend it shouldn’t influence your choice of grinder too strongly.
Burr size and motor power generally go hand in hand: the larger the burrs, the more powerful the motor. Generally speaking, the larger the burrs and more powerful the motor, the quicker the grinding speed and the more capable the grinder is at running for longer periods without overheating. They’re also less prone to generating static than their smaller less powerful counterparts – statically charged grounds are a pain as they have a habit of floating away from where they’re meant to be and generally making a bit of a mess!
Of course, you can also get manual grinders so the power you put in is generally what you get out.
Stepped grinders have a number of fixed grind settings, with the number varyingly from grinder to grinder. Generally speaking the more grind settings the better, as it means there’s a smaller change when moving from one setting to the next. This is advantageous as the smaller the change the more control you have to tweak the grind to improve the flavours in your coffee. If you intend to use your grinder with an espresso machine, you will need at least 30 settings or, better still, opt for a stepless grinder.
Stepless grinders have no fixed settings. Instead you can adjust the distance between the burrs practically anywhere between where they touch, until the point where the gap between them is so large the beans fall straight through. The drawback with stepless grinders is that most have no markings to indicate how coarsely the grinder is set. This can be a little overwhelming for newbies, as it takes a lot of trial and error to find the correct grind setting. It also presents a problem if you’re planning to use the grinder with a number of different brewing methods as it’s difficult to adjust the grinder from one brew method to another and back again without wasting some coffee searching for the right setting.
Coffee grinders are fitted with one of two systems for dispensing ground coffee: doser or doserless. Doser grinders are fitted with a special cylindrical container which is designed to portion the grounds into repeatable doses. One pull of the doser’s handle is intended to dispense a certain weight of coffee. However, for the doser system to work accurately, the dosing container needs to be at least half full of coffee, which goes against our earlier advice of only grinding your coffee immediately before you need it. However, the dosing system isn’t completely superfluous for those wanting to grind on demand; the action of the doser does a good job in breaking up clumps in the grounds which commonly occur when grinding finely.
Doserless grinders are often called ‘on demand’ grinders as they’re designed to be used as and when you need them. The ground coffee either: comes directly out of a shoot for you to catch in whatever utensil you chose (such as a portafilter); or is fitted with a removable container that simply catches the grounds.
As to which system is best: doserless grinders are probably slightly more practical for home use, because doser systems tend to retain a small amount of grounds in the base of the doser and so regularly need cleaning out. However, there’s nothing wrong with doser systems – some people actually prefer them – so you shouldn’t be put off a grinder just because it’s fitted with one.