Fine coffee common sense filter cup brewing coffee

When using a filter cup to brew coffee, many people do not know what the groove of the filter cup is for.

In fact, when we use flannel dripping, the air can be discharged from anywhere, and when using a filter cup, the filter paper will be attached to the filter cup wall, so the air can only be discharged from the filter hole at the bottom of the cup. as a result, the air that cannot be discharged will flush out from the surface of the steaming coffee powder, making the cold air enter, resulting in incomplete steaming. The trench is to prevent this from happening.