Grinders and grinding
Just like when painting with oils, you need the right skills to grind coffee. It is attention to detail that makes the difference between a picture and a work of art. The same applies when it comes to coffee. This is why we don’t just grind by numbers – we use our expertise and intuition.
Before it ends up in your cup as a perfect espresso or lungo, coffee goes through a number of different processes that can significantly affect the final result. One of these processes is the grinding of the roasted coffee beans. The grind influences how long the extraction takes and how many aromatic substances are released from the coffee. But let’s address the most important question first.
The question why
Why not simply brew up the roasted whole beans? The water needs to come into contact with as much surface area as possible during extraction to allow the different substances and flavours to be released from the coffee. Whole beans have a relatively small surface area, which means that hardly anything would be extracted during the short time in which water and coffee are in contact. When roasted coffee beans are ground, they are broken down into small parts. Breaking down the beans into thousands of particles radically increases the surface area that will come into contact with the water. This allows the coffee to release a lot more substances and flavours.
Patience is a virtue
Once the beans have reached the desired roast during roasting, they need a period of rest before further processing. Due to the residual heat, the particles inside the coffee bean are still moving too much, and the remaining moisture and oils inside them are unevenly distributed. Grinding the warm coffee beans results in different grain sizes and oily residues. We therefore give the freshly roasted beans a short but important break before grinding. This is the only way to ensure an even grind. Good things come to those who wait.
The grinder is key
Different types of grinders are used to grind coffee beans. Propeller grinders break down the beans with a rotating metal blade, much like a food processor. With this type of grinder, the grind is very uneven, with both fine and coarse particles being produced. This results in too many substances being released from the fine particles and hardly any flavours being released from the coarse particles during extraction.
Disc and conical grinders are far more effective. These break down the beans between two discs or a cone and the wall of the grinder. The distance between the grinding surfaces can be set to the desired grind. The ground coffee only falls into the funnel once the beans have been ground to the desired size. This creates an even grind, which in turn has an extremely positive effect on the sensory quality of the brewed coffee. As with a kitchen knife or a pair of scissors, it is important that the cutting surface remains sharp and thus efficient. If the cutting surfaces become blunt, it is worth replacing them.
For our Café Royal capsules, we use a triple-pair roller grinder. The coffee beans are cracked open in the first section and ground progressively finer in the second and third sections. This grinder can be adjusted precisely to the desired grind and creates the perfect grind for each product or capsule. Every grind can be reproduced, which ensures consistency and quality.
Aromatic gases are released when the beans are ground. A fine grind means a larger surface area and increased exposure to oxygen, one of the many aroma killers. This allows the gases to be released from the coffee more quickly, and the coffee loses its flavour more rapidly. This is why it is important to package ground coffee in airtight packaging immediately or to use it quickly. In our coffee capsules, the freshly ground coffee is well protected and therefore lasts much longer without losing its flavour.
It’s all in the grind
Selecting the correct grind is essential for the quality of the end result in the cup. The strength of the roast and the preparation method are also crucial when deciding on the grind. A fine grind is suitable for espresso machines, a medium grind is ideal for filter coffee and a coarse grind is used for a French press. For our Café Royal products, we select a grind that is tailored to the preparation method. This allows us to get the best flavour out of every capsule.
If the coffee is ground too finely, lumps can form and the water can barely pass through the coffee. However, if it is too coarse, the water needs more time to extract the flavour from the coffee.
Extraction in action
The grind determines what happens during extraction. Coffee extraction means releasing the substances and flavours from the ground coffee using hot water. The quality and temperature of the water are key. If the water is too hot – above 95°C – darker roasts can be overextracted, which results in an undesirably bitter taste. However, if the water is too cold, the aromatic substances are not released from the coffee and it tastes bland and watery.
A further factor that is crucial for the optimal extraction is the length of time that the water is in contact with the coffee. If the extraction takes too long and the water is too hot, the aromatic substances evaporate and the coffee develops more bitter substances. Underextracted coffee, however, hardly develops any flavours, tastes bland and often has an unpleasantly bitter acidity. If the coffee is prepared using pressure, more aromatic substances are developed more quickly. For capsule systems, the grind is tailored to the high pressure, optimal temperature and short extraction time.
As you can see, coffee grinding is a science in its own right. You might find the ideal grind by tinkering and experimenting – or you can simply trust the intuition of our Café Royal coffee experts.