4. Grinding Cutter of coffee grinder (Coffee grinder knowledge summary)
Mis à jour : 28 nov. 2019
The core part of the grinder is the cutter.
The cutter are classified according to the grinding method and the shape of the grinding teeth. There are four types of them: flat burr, conical burr, ghost tooth burr, round burr.
The upper and lower burrs grind coffee powder in cutting process.
The coffee powder that comes out is mostly in the form of flakes, and the surface area for extracting contacting water is larger, and it is easier to extract faster.
There is an advantage in making espresso coffee for this burr.
However, Due to the fast extraction speed plus more fine powder, it is easier to over extract. There is also a disadvantage in the taste if shorten the extraction time.
It is more efficient to grind coffee bean by the flat burr relatively. And it is suitable for fast-paced use in cafe or shop or juice bar. The disadvantage is that it is easy to over extract.
There are also a lot home use coffee grinder with flat burr, and this flat burr is one of the most common cutters on the market.
The most suitable coffee grinding burr for grinding espresso coffee powder.
Grinding in a crushing manner.
The coffee powder is granular and the inside of powder is not easily extracted quickly.
The coffee made by this burr has a multi-layer flavour. And the way of crushing reduces the collision between the coffee beans. So the fine powder rate is lower, which is generally more suitable for making hand-brew coffee.
However, while the interior of the coffee powder is completely extracted, the outside cannot be over extracted, which is a technique that requires considerable temperature control and time control.
The coffee powder ground by the conical burr is suitable for hand-brew coffee, siphon pots etc.
Round burr and ghost tooth burr
Both the round burr and the ghost tooth burr are a kind of tooth shape burr between the flat burr and the conical burr, which is an attempt in the process of upgrading the coffee grinder cutter.
The round burr actually is adding the crushing method into the flat burr, which makes the coffee taste more rich. The good result is that the coffee taste is more clean, the sweetness is more prominent, and it is easy to capture the coffee flavor, which make the taste suitable for the most people.
Compared with the round burr closer to the flat knife, the arrangement of the ghost tooth burr is more bold. The ghost tooth burr can theoretically grind the coffee powder closer to the spherical shape, reducing the fine powder rate and making the coffee taste more clean.
However, in fact, the technical materials of the cutter like the flat burr, conical burr and round burr are very wide. The hardness can be improved by heat treatment. The surface anti-oxidation treatment can also be performed. They are all can be precisely machined.
But because of the special shape, the grinding burr of the ghost tooth can only be formed by casting in one time. There is no way to perform secondary processing by precision instruments. Therefore, the surface is rough and the precision is not high. It is also true that if thermal processing is used to increase the hardness, deformation will occur.
Therefore, the Grinding burr of the ghost tooth is generally not sharp enough. Only reach the level of cast iron.
I prefer the coffee taste made by the round burr. As for ghost tooth burr, pure hand-made burr, the price will be much not worth.