Espresso production: degree of grinding (1)

I talked about the steps of pressing powder in the process of making Espresso and the strength of pressing powder, and mentioned a little about the factors that affect the strength of pressing powder, one of which is the degree of grinding of coffee powder.

Grinding refers to the process of grinding coffee beans into the coffee powder used in making coffee by using a bean grinder (or manual grinding apparatus), and the degree of grinding refers to the thickness of the coffee powder. So what is the impact of the degree of grinding on Espresso production? Today, let's take a look at the impact of grinding on the production of Espresso.

Because Espresso uses a coffee machine, about 95 ℃ of hot water passes through coffee pressed powder at 9 atmospheric pressure, and the coffee is extracted for 25 seconds to 30 seconds to get about 30cc coffee. The extraction time is short and the coffee pressed powder is under great pressure, which puts forward a requirement for the grinding degree of coffee powder, which is different from that used in other coffee production methods-the coffee powder for making Espresso should be fine grinding.

What is fine grinding? If the degree of grinding of coffee powder is roughly divided into fine grinding, medium grinding and coarse grinding, then the drip filter may be more suitable for coarse grinding, while handbrewed coffee and siphon pots may be more suitable for medium roughness, while mocha pots are more suitable for fine grinding, compared with the coffee powder for Espresso. Therefore, the degree of grinding of coffee powder made of Espresso should belong to fine grinding or fine grinding.

So what effect would it have on the production of coffee if not for the use of this degree of grinding?

The production of Espresso has strict requirements on the grinding degree of coffee powder. Assuming that there is a suitable grinding range, then this range is also quite small, a slight change in the grinding degree of coffee powder will have a great impact on the coffee produced. This effect can be seen even in the process of making coffee. For example, if you thicken the degree of grinding a little bit, under the same other conditions, you will find that the extraction time of 30cc coffee becomes shorter, and although the extraction state of coffee is stable, the color of coffee quickly becomes lighter; if you adjust the degree of grinding slightly, you will find that the time of extraction of 30cc coffee is longer, and the coffee has finer rheology and darker color. The taste of coffee made in these two cases will be very different, and there will be a significant difference between coffee made with a more appropriate degree of grinding.

Some people may say that since the degree of grinding has been adjusted, other elements should be adjusted accordingly to match the adjustment of the degree of grinding. For example, now that the grinding degree is thickened, the strength of the pressing powder should be increased to make the coffee pressed powder denser so as to achieve the purpose of prolonging the extraction time, on the contrary, the detailed rules of grinding degree adjustment should reduce the powder pressing force. It seems to be so, but it is not appropriate to do so.

First of all, the strength of pressing powder is formed by finding a familiar feeling after a long time of repeated practice, so the practice of constantly changing the strength of pressing powder with the grinding degree is not conducive to better mastering the feeling of pressing powder, and it can not be changed to exactly the degree you want at once, but the feeling of strength is more inaccurate over time. Even under the right grinding degree, the coffee production will fail because of the inaccurate strength of the powder pressing.

Second, even if you change the degree of grinding and change other factors to make the coffee more in line with the requirements mentioned in the definition, it will be different from the coffee made at the right degree of grinding. the difference lies in the taste of the coffee. Because of the change of grinding degree and the change of the surface area of coffee powder, the coffee ingredients extracted at the same time are different. In fact, as long as we understand that we want to get a cup of Espresso that meets the definition and has a good taste, rather than a coffee that is light or muddy and complex in taste, we can understand why the right degree of grinding is so important.

So does it mean that the degree of grinding can not be changed? What factors will affect the degree of grinding? In the next article, we will continue to learn about the factors that affect the grindability of the coffee powder that makes Espresso.