How to solve the electrostatic problem of coffee powder? Can spraying water on coffee beans remove static electricity? How will the grinding quality be affected?

Static electricity, a "stumbling block" of coffee beans on the grinding road, not only makes a large number of flying powder stick to the channel, but also often brings great trouble to the extraction process because of caking.

In order to effectively "prevent" static electricity, bosses in the industry have also made a lot of efforts on all kinds of appliances, such as installing anti-static tablets on the powder outlet of Italian bean grinders and tapping back and forth with tinkling cups to solve larger pieces of powder. after receiving the powder, use a cloth powder needle to break up the lump. In addition to these, there is another method that is widely circulated on social media: sprinkle or spray water on beans.

If you like to surf the Internet as much as the front street, I believe you may have seen this in some videos: first weigh a single serving of coffee beans that need to be grinded. Find a small spoon to scoop up 1 or 2 drops of ordinary drinking water (or spray them with a spray bottle), then wet their surface and stir them properly, and finally grind the coffee beans normally. They believe that this will not only prevent coffee powder from caking, but also make the espresso taste more rich and uniform.

In fact, in the coffee grinding process, the coffee powder will be charged due to the friction between the coffee bean and the blade and the uneven charge distribution in the coffee cracking process. The finer the grinding, the more static electricity the coffee powder will produce. Static electricity will cause the negatively charged fine powder to attach to the larger particles, forming a lump of 1 mm to 2 mm, which looks like an irregular lump to the naked eye.

In theory, such clumps will not only reduce the contact surface area between coffee and water, but also cause the uneven flow of hot water in the coffee powder bed, thus disturbing the extraction rate of soluble substances, which is often called "channel effect". It is often accompanied by spatter and perforation.

At this time, by adding external water to the beans, the charge on the coffee powder can be adjusted, so as to reduce the disturbance caused by static electricity, and avoid the problem of condensation and agglomeration of coffee powder, so as to achieve more uniform extraction.

This claim was confirmed by a new paper published by the University of Oregon in Matter magazine late last year. Combined with various studies, the team pointed out that spraying an appropriate amount of water before grinding coffee beans can effectively prevent static electricity and improve the extraction rate of coffee.

The paper also mentioned that the static electricity of coffee beans with different roasting degrees will be different due to their different internal water content. For example, shallow baked beans have more internal moisture, less static electricity is obtained during grinding, and mainly tend to be positively charged, while deep baked beans are drier, get more static electricity during grinding, and tend to be negative, so it is easier to adsorb on channels or containers, as well as agglomeration, so the effect of applying RDT will be better.

Over the years, RDT, like WDT, has been favored by many family baristas who have flexibly applied this technique to their daily coffee. But we seldom see such an operation in the bar of a coffee shop. Why?

It is not difficult to find that this "sprinkling" technique can only be used in a single dose of coffee brewing, and most of it is concentrated. Because after adding water, the coffee beans are already damp, and the aromatic compounds responsible for flavor begin to decompose, which requires us to grind them quickly, otherwise the aroma will be greatly reduced.

In addition, most of the equipment produced in stores are commercial bean grinders, so baristas rarely need to think about static electricity and caking alone, because such appliances are equipped with "antistatic film" devices. And in the daily production process, compared with spending tens of seconds or even minutes to spray water for coffee beans, grinding, using cloth needles and other tedious steps, how to make a good cup of espresso more efficiently is everyone's top priority.

As a perennial "veteran" coffee maker, Qianjie believes that there are certain risks in using this method. If you do not pay attention to it and spray too much water, it is easy to make the coffee powder damp and agglomerate. Long-term mixed with water droplets, there will be the probability of rusting the cutter head. In other words, the loss may outweigh the gain if it is not properly controlled.

If we really need to use RDT for intervention grinding when making espresso, Qianjie thinks we might as well refer to our coffee industry god James Hoffmann's method: dip the spoon back into a cup of drinking water, then put the spoon handle with water droplets into the coffee beans, stir quickly a few times, and then start grinding.

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