The 4M and the perfect espresso grinder

For a true espresso lover, the perfect "little black coffee" in the cup is more than just a caffeine shot - it is a piece of joie de vivre, a pleasure, a 5-minute holiday in Italy. That's why the true espresso connoisseur makes no compromises when it comes to quality - regardless of whether it's the amateur barista at home, the guest in the catering trade or the professional barista.

To conjure up the perfect espresso in a cup, all "4M" have to play their part: The (coffee) blend, the Machinethe person and the Grinder.

And while most (hobby and professional) baristas and restaurateurs attach great importance to a High quality espresso machine and on the optimal coffee bean, the exact fourth "M" - the Grinder - unfortunately often criminally neglected in practice.

Here we explain why the perfect espresso cannot be made without the perfect grinder, and what you should look out for when choosing the ideal grinder.

The four "M "s of the perfect espresso

In order to have a perfect espresso in the cup, many factors have to come together. By the way, this also applies to the perfect cappuccino, latte macchiato, Americano and all other coffee drinks, the basis of which is always the perfect espresso.

First of all, of course, the coffee used - the first "M", the blend - must be right. It goes without saying that neither the perfect machine, nor the perfect grinder, nor the perfect barista can turn a bad coffee into a good one. Just as the best cook with the best pans and the best cooker is powerless if the meat is simply inferior.

Then the water temperature must not be too hot or too cold, and the pressure profile of the espresso machine must optimally extract the various ingredients of the espresso - the second "M", the machine, is responsible for this.

The third "M", the person - the barista - must understand his craft. He has to do the right things in the right order: flashing, tamping, foaming the milk. The best way to learn this is in our professional barista courses - you can find the next available dates here.

But all this is of no use if the fourth "M" - the mill - does not fulfil its tasks.

The "fourth M" - the mill

The perfect espresso needs an extraction time of around 25 seconds, depending on the bean. With a shorter brewing time, not all the desired flavours and ingredients are extracted - the espresso becomes under-extracted and "thin". With a longer extraction time, unwanted bitter substances are drawn out of the coffee grounds - it becomes bitter and undrinkable.

How do you control the extraction? Imagine a glass with pressed sand and a glass with loose pebbles through which water runs: while the water seeps extremely slowly through the pressed sand (over-extraction), it runs too fast through the pebbles (under-extraction).

Translated to our espresso, the sand corresponds to extremely fine, the pebbles to extremely coarse ground beans. The effect is further enhanced by the amount of "sand" or coffee in the portafilter: the water runs faster through a small amount of pressed sand than through a large amount. And the last factor: The same amount of finely ground beans has a significantly larger contact surface with the hot water than coarsely ground beans - so more ingredients and thus flavour are released .

The optimal coffee grinder therefore ensures that the same amount of equally finely ground espresso always ends up in the portafilter. Not too much and not too little, not too coarse and not too fine. Andabove all - this is the most important and most difficult thing - always evenly.

And once you understand this, it is also clear why the perfect espresso can only be made with the perfect grinder - and why it is absolutely wrong to skimp on the grinder.

In addition to the quality of the grinder, however, there are other features that are important when choosing the optimal grinder - we will take a brief look at these as well.

Stock grinding vs. grind-on-demand

In the past, grinders with stock grinding were standard: the container with the whole beans on top, the container with the already ground coffee on the bottom. Today, hardly any barista uses this, for two reasons.

Firstly, the aroma of a ground coffee bean dissipates after a very short time - after an hour at the latest, the bean is "dead". Secondly, the coffee is dosed from the grinder by means of a lever pull - on the one hand, this cannot be regulated finely enough, and on the other hand, a double shot (two espressos) does not need exactly twice the amount of ground coffee as a single shot, and this is not feasible with a grinder.

That's why we advise you to stay away from grinders. If at all, they are still justified at Italian motorway service stations, where so much espresso is consumed that the bean has no time to "smoke out".

Instead, so-called "grind-on-demand" gr inders are standard today: Here, each portion is freshly ground individually - and single and double shot can be optimally adjusted individually .

Do grind-on-demand mills also have disadvantages? Yes - on the one hand they cost a little more. But the mill should simply be worth it.

Secondly, each portion has to be freshly ground, and that takes a bit more time than just pulling the supply lever once or twice. That is why it is important to choose a mill with appropriately sized grinding discs - the larger the grinding discs, the fasterthe grinding (and, incidentally, the longer the shelf life and the lower the heat generation).

A small grinder - such as the Mazzer Mini electronic - needs around 12 seconds of grinding time for a double shot. This is not a problem for the ambitious home barista, but it is simply too long for a well-run espresso bar. A Grinder with large grinding discs manages this in around 4 seconds.

If that still takes too long, there are special mills that always pre-grind exactly one portion - this is available immediately, and the next portion is then freshly ground again. There is no waiting time at all, but these machines are only worthwhile at extremely busy locations, because they cost even more.

The size of the bean container

So while the size of the grinding discs directly influences the grinding speed, the size of the bean hopper is less decisive: if it is smaller, you simply have to refill it more often.

But here the rule is: less is more! Because the whole, unground bean is also exposed to the elements - light, air and moisture - in the bean container and accordingly ages much faster, albeit much more slowly than the already ground bean.

We therefore recommend that you do not store more than a day's worth of coffee in the storage container - and if necessary, refill it briefly if the container does run out.

How many mills do you need?

One last quick note: Of course, a grinder can also grind only one type of coffee. If you want to offer different beans - e.g. a 95-5 blend (95% Arabica, 5% Robusta) for pure espresso and a 60-40 blend for milk drinks like cappuccino - then you need a second grinder.

But especially for Caffè Crema - the long cup of coffee from the portafilter - we recommend a second grinder. On the one hand, the Caffè Crema bean is different from the espresso bean (different bean, different roasting). On the other hand, at least 120 ml must flow through the portafilter in around 25 seconds (as opposed to around 30 ml for espresso). Think of our example above with the sand and pebbles: Here, the bean must be ground much coarser.

So if you want to deliver both espresso and Caffè Crema in perfect quality, you need two grinders. Of course, you can use a smaller, cheaper grinder for the Caffè Crema, which you usually need less often.

Our conclusion

Our conclusion can be summed up quite succinctly: never skimp on the espresso grinder!

A perfect espresso machine, an expensive fine coffee and a trained barista - all this is simply useless if the grinder grinds irregularly. Full stop.

Sometimes the conclusion can be that short and simple...