What is the grind standard for hand-brewed coffee? How to accurately find the grind degree of hand-brewed coffee?

The reason why most friends can't make coffee well is that they don't choose the right degree of grinding of coffee powder. This is a sentence that Qianjie has been emphasizing all the time, because very often this is the case.

The extraction rate and concentration are the two keys to determine whether a cup of coffee is good or not, and in the process of coffee making, there are four important factors that can control the extraction rate and concentration of coffee: grinding, proportion, time and water temperature. The parameters of each factor will affect the extraction rate of coffee, so to make a good cup of coffee, we need to use the relative extraction parameters.

Among these four factors, only the degree of grinding of coffee powder is invisible, and the parameters of the other three can be seen intuitively. So, when we use the same ingredients (beans and water), the same way of brewing, and seemingly the same parameters to brew a pot of coffee but not as good as the restaurant, there is no doubt that the problem lies in the grindness of the coffee powder.

Because the thickness of coffee powder is not intuitive, most of the time we can only use visual and tactile judgment, and then compare them to fine sugar, coarse sugar and other substances. But this description is not reliable, mainly because the scope is too wide, everyone's definition of sugar particle size is different, and the coffee powder size seen from the appearance is only superficial. So, how can we accurately find the right coffee powder to grind? You might as well refer to these three ways shared in the front street below.

The sieve measurement method "how much and how much the sieve rate of the No. 20 sieve" is a parameter often shared by Qianjie in the article, which is the value obtained by using the No. 20 sieve to measure coffee powder. Compared with other ways, the use of the screen can provide a more objective standard, and the error will not be so great. Because everyone uses different machines and beans, there is no way to communicate the specific grinding degree through the model of the machine and its scale. Even the same machine and the same scale will lead to differences in the thickness of the ground coffee powder due to the different degree of wear of the cutter head. On the other hand, the use of the No. 20 screen can provide a relatively reliable data, even if we use different instruments and materials, we can also adjust a similar degree of coffee grinding through the measurement of the No. 20 screen.

The aperture of the No. 20 screen is 0.85 mm, and its box-shaped design is divided into two layers. The operation mode is very simple, we only need to put a certain amount of coffee powder into the sieve and shake it! Shake until there is no coffee powder passing through the sieve. Then we only need to measure the weight of the coffee powder, and then we can get an intuitive result. For example, if 10g coffee powder is put in Qianjie, and then 7g coffee powder passes through the sieve, the over-screening rate of this coffee powder is 70%. If others want to use the same degree of grinding as you do, you only need to adjust the grinding to a 70% overscreening rate of coffee powder. No matter what kind of machine, no matter what kind of beans are ground, they are universal.

The following is the degree of grinding used in brewing hands in the front street, which you can refer to: the grinding rate of hot coffee is 80% of that of screen 20, and that of iced coffee is 85% of that of screen 20. However, the sieve method also has some defects, which is that it can only distinguish the particles larger than / less than 0.85mm. How much effect does the grinding of coffee beans have on the extraction? Qianjie highlighted in this article that coffee grinding results in different sizes of particles due to its grinding properties. Even the better quality bean grinder can not be completely uniform, it can only control most of the coffee powder in a certain range. (here is a coffee powder ground by Ek43. Qianjie uses a sieve to distinguish it from large, medium and small particles.)

Therefore, when the quality of the bean grinder we use is low, or the knife head is blunt, the coffee powder will be very uneven. Even if our value is the same as the screening rate of others, there will be a big difference in taste. In a case like this, Qianjie will suggest that there are two other ways to identify the degree of grinding of coffee powder.

The launching speed and extraction time of coffee powder will affect the launching speed. The thicker the coffee powder is, the faster the launching speed is, and the finer the coffee powder is, the slower the launching speed is. The speed of launching is related to the contact time between water and powder. The longer the extraction time is, the higher the extraction rate of coffee is, and vice versa. Therefore, when all other parameters are fixed, we can judge the grinding thickness of coffee powder by the speed of launching.

In the former street, for example, the amount of powder used to brew a pot of shallow roasted coffee in the front street was 15g, the water temperature was 92 °C, the ratio was 1:15, and the time would be in the range of 2 minutes to 2.5 minutes. If the final brewed coffee is out of range, then we need to make relative adjustments to the grinding. Because all the parameters have been fixed, the only thing that can change the extraction time is grinding. If the speed of launching is too fast, the degree of grinding of fine coffee will be adjusted, and if it is launched too slowly, the degree of grinding of coffee will be adjusted. It is such a simple reason.

Of course, it is not entirely desirable to measure the quality of a cup of coffee by extraction time alone, so we need to identify it by combining the third situation: taste.

Taste as said at the beginning of the front street, the extraction rate is essential for a cup of coffee because it represents how many ingredients are dissolved in the coffee. These ingredients are the main providers of coffee flavor, and when they dissolve too much or too little, they reduce the positive experience of a cup of coffee. So by tasting the coffee, we can tell whether the grinding of the coffee needs to be fine-tuned.

The specific principle of the front street before the "coffee tastes bad? It is mentioned in detail in this article that teaches you to distinguish between over-extraction and under-extraction, so here is a brief explanation of how to judge whether coffee is poorly extracted by its performance. When coffee dissolves too little, it is what we call insufficient extraction. Due to the lack of a large number of sweet and bitter substances to balance the sour taste, the coffee will have a relatively exciting sour taste at this time. Not only that, the taste of the coffee will be very thin because of the lack of material, basically without any tail rhyme. If we get this situation from coffee, then when other parameters remain the same, we need to improve the extraction rate of coffee by fine grinding.

And if the coffee taste is very full, but with obvious miscellaneous, bitter taste, it is likely to be excessive coffee extraction. In this case, if the other parameters remain the same, then we can reduce the extraction rate of coffee by roughing and grinding, so that the bitter and miscellaneous taste of coffee can not be dissolved too much. The above skills are based on the relatively stable quality of the bean grinder, if the quality of the bean grinder is too poor, or the knife head is too blunt, and the fine powder is very much ground, so that the coffee liquid is seriously clogged in the process of extraction, it is best to replace the bean grinder. Of course, we can also achieve the purpose of reasonable extraction by adjusting other parameters. But this is a deeper understanding of the extraction theory, how to choose how to adjust, it is up to everyone.

-END-