Effect of grinding by bean grinder on coffee flavor

There are four main factors affecting extraction by bean grinder:

Evenness: coarser coffee particles are more likely to be underextracted, while finer particles are overextracted in advance, so the coffee powder with a larger span of grinding thickness can taste more turbid and irritating smells. When the coffee powder with the same size and similar shape is used for extraction, the taste becomes brighter and stronger, and the performance of flavor characteristics is clearer and consistent.

The amount of fine powder: coffee powder close to flour can easily be overextracted or even dissolved in water, thus affecting the extraction taste of coffee. The more fine powder, the more easily coffee is over-extracted, and the more bitter the taste is, the more mixed it is. When making espresso, the fine powder will first be washed out by the water and into the cup. If extracted properly, the thick oil will hold up the fine powder, and the fine powder will float on the surface of the oil, forming a beautiful "tiger spot". But "tiger spot" does not represent the taste of espresso. The production of fine powder can be reduced by choosing a better bean grinder or using a sieve. However, if there is no fine powder at all, the coffee brewed will also lack a sense of hierarchy, and the balance can only be put into practice, not in words.

Calorific value: the grinding plate of any bean grinder will generate heat in the grinding process, and the heating of coffee powder will accelerate the oxidation process and accelerate the volatilization of aroma, resulting in the weakening of coffee flavor after brewing. The calorific value of the cutter head depends on the size of the grinding plate, the material used, the structure of the knife, the fineness of grinding, the speed of the motor, the hardness and texture of coffee beans and many other factors. Therefore, at present, large brands of bean grinders begin to be equipped with heat dissipation windows, cooling fans, choose more heat-dissipating metal, or drive the cutter head with higher torque and low speed motor, so as to reduce heat generation.

Static electricity: generally speaking, the finer the grinding, the faster the grinding machine, the stronger the static electricity generated; the internal material is plastic, and the lower powder mouth does not use the bean grinder designed to reduce static electricity, so the static electricity generated is stronger; the coffee beans with rich oil and deep roasting are ground, the static electricity generated is stronger. When grinding the Italian bean mill, the fine powder often appears as a ball, which affects the density of the powder, resulting in uneven extraction, while the iron absorber at the outlet of the single bean mill absorbs silver skin and fine powder through electrostatic adsorption. to help reduce the taste and odor of excessive extraction.