Classification of hand-made filter cups. Coffee-making utensils by hand.

Filter cup

Filter cup is the most basic tool in hand-brewed coffee, which is generally divided into cones and triangles, while triangular filter cups are first widely used in hand-brewing types. In this article, the principle of hand-brewing is introduced, and the triangular filter cup will be used as the main explanation.

Hole number

At present, the filter cup brands that can be found on the market are Melita filter cup which has been widely used and Kalita filter cup from Japan. The biggest difference between the two is the difference in the number of holes at the bottom. In the early days, there was only one hole in the bottom of Melita, but its disadvantage was that when the coffee was worried too much, the hole was often blocked by fine powder, which made the coffee soaked in the water for too long and made the coffee bitter. Therefore, the brewing method of adding water was adopted for this kind of filter cup, in the hope that the coffee particles could always float on the surface, but the relative problem was that the coffee particles were soaked in the water for a long time. It will affect carbon dioxide emissions and reduce the extraction rate, so a three-hole Kalita filter cup will be derived later.

Rib frame

In addition to the number of holes, we can also find that there are protruding designs in the filter cup, which we call the ribs of the filter cup. The main purpose of designing these ribs is to prevent the filter paper from being affixed to the filter cup, so that the hot water poured into the filter cup will flow directly along the filter cup wall through the filter hole and run to the next pot, so that the hot water soaked coffee powder will not be able to extract the coffee liquid, which will eventually reduce the extraction rate. The taste will also become thin and light. The drip punch is supposed to replace the troublesome flannel, but the filter paper is a fragile material, so a filter cup is needed to prevent the powder layer from collapsing during water injection, and the filter paper itself will permeate. If it is completely attached to the filter cup, the water will flow directly through the filter hole on the cup wall and reduce the extraction efficiency, so there is a rib design on the filter cup, which can help the distance between the filter paper and the filter cup wall to prolong the time for coffee particles to be immersed in water. After being soaked in hot water, coffee particles will emit carbon dioxide, and many bubbles will be seen on the surface, while the internal particles will expand because of absorbing hot water. In addition to the path of discharge to the surface, there is also one of the exhaust paths around the filter paper, but if the filter paper is close to the edge of the filter cup, the heat cannot be discharged smoothly, so the coffee particles suffocated at the bottom will be affected. As a result, the injected water can not be absorbed by the coffee, and the amount of extraction is reduced.