How to find the right grind for your coffee machine Part 1 How to adjust and why.
What is the right size grind for a coffee machine?
This is the first of a two part series on helping you find the right grind. It covers the grinders functions and how to adjust them. It will also help you understand the correlation between espresso and the ground coffee particle size.
One of the biggest contributing factors towards the flavour of your espresso coffee is the grind texture.
Principle behind espresso making.
A true Espresso coffee has a persistent golden mahogany coloured ‘Crema’ floating on top of the coffee.
Firstly I’d like pay homage to Italy for the invention of the Espresso Coffee. A love that has come to be appreciated by all coffee lovers throughout the world. Congratulations!
Definition of espresso.
So, the variables we have left to control our coffee extraction rate, is the grind texture particle and the ground coffee dose.
Principle behind grinding coffee.
Grinding coffee is the process by breaking up the coffee bean size into defined finer particles.
Now what happens during the grinding process. The coffee beans fall into the grinding discs via gravity. From there they travel in between the grinding discs via the rotation of one of the discs.
The burrs are machined in a specific directional pattern as to allow the coffee to flow through the blades. Hence, preventing the overgrinding and heating of the coffee. As the coffee is being ground it centrifugally falls into the outlet chute ready to be brewed.
A coarser grind has a larger gap between the two blades. And a finer grind has a smaller gap between the two blades.
Types of grinding blades
There are two main types of grinding blades, flat discs and conical. The conical blades work in the same way as the disc blades. The only difference is that
they’re cone shaped and rotate at lower revolutions.
What role does the correct grind size texture play in espresso.
Grind texture offers resistance against the pressurized hot water, hence determines the extraction flow rate of your espresso.
Tamping the coffee
It’s important to always evenly tamp your coffee with constant pressure. This allows the hot water to evenly moisten the coffee as it extracts all the flavour.
In addition, a firmly packed coffee cake provides even resistance against the hot water.
If the coffee cake is unevenly packed or isn’t firmly packed there’s a good chance of channeling occurring. What this means is that the hot pressurized water will find the weakest point first (an area offering less resistance) and penetrate through it.
This results in an uneven distribution of flavour and a flat tasting coffee. You’ll notice the crema seems a little different in colour. It’s quite tricky to detect during the extraction, but it’s visible when you remove the handle from the coffee machine and look at the moisten coffee grounds. You’ll notice small indented holes in the spent coffee grains.
Ground coffee dose
“If you don’t keep the ground coffee dose constant, you will end up going round in circles and become extremely frustrated.”
Let’s look at ground coffee particle size.
A finer grind setting slows down the extraction flow rate. A coarser adjustment speeds up the extraction flow rate.
Grinder adjustment – Getting the right size grind for a coffee machine.
Getting the crema right is a good visual indication in helping you nail the grind.
Today there’s a huge range of grinders on the market available for home or commercial use. They either have a stepped or an infinite adjusting collar/wheel/knob.
The stepped adjusting wheel has preset grinding intervals. Whereas the infinite adjusting wheel is limitless and offers more accuracy.
Once you get the right size grind, you’ll then appreciate that the infinite adjustment is the way to go.
Which way is finer
Ensure you look at the labelling direction of the adjusting wheel/knob before attempting to make any adjustments.
Grasp the understanding of the adjusting direction especially if you’re a beginner.
Why do you need to adjust your grinder
The sole purpose of adjusting your grinder is to improve the flavour of your espresso.
- Thin pale coloured crema.
- The coffee lacks body.
- Extraction time very short. (below 18 sec’s)
- Extraction time too long. (over 40 sec’s)
- Different pack of coffee beans.
- Coffee beans are too fresh.
- Coffee is starting to stale.
By now your probably thinking this is all too much, why did I buy a grinder. Don’t worry, hang in there and once you have a few attempts you’ll grasp the concept.
From there on you’ll know when and how to adjust your grinder. It’ll only take you a few seconds – guaranteed. I’ve trained hundreds of people over the years and once they get it, they don’t forget it.
It’s amazing to see people learning espresso extraction for their first time. What impresses me is how quickly they can visually understand if the coffee flow is acceptable or not. You too can do this. It’s a matter of building confidence and this can only come by having a go. Just do it, you’ll be fine.
Since the grind texture particle size will affect the extraction time, then your grind adjustment is the most important function that will allow you to make espresso coffee within the parameters. So, start adjusting here.
End of part 1.
Well done, you’re half way there.
We’ve now covered the principles of espresso and the grinder, the relationship between espresso and the ground coffee particle size. We also covered the functions of the grinder and how to adjust it. We defined an espresso and explained the importance of keeping all variables constant such as the tamping and the ground coffee dose.
So, by now you should have a fairly good idea of why you need to adjust your grinder and what happens to the coffee when you do.
If you are experienced with using a grinder you may now want to attempt to find the right size grind for your coffee machine. However, I suggest you also read, How to find the right grind for your coffee machine part 2. In our second post we cover real scenarios and problems to avoid.