Why is the coffee filter cup funnel-shaped? Will different filter cups affect the taste?

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The coffee filter cup was originally cylindrical, and then in order to shorten the extraction time, it was made into a funnel to increase the extraction surface area.

Author = Xin Jixu (founder of individual work room of Yonsedong Coffee Workshop in South Korea)

The filter cup is a funnel-shaped prop filled with coffee for extraction. It was invented by Melitta Bentz in Germany in early 1900. At first, the appearance was to make a hole in the bottom of the metal can with a nail. In order to prevent the coffee powder from flowing out of the hole, a piece of filter paper was put on it. Later, after gradual improvement, it became what it is now. The most important change is from a cylindrical jar to a funnel.

Why should the filter cup be made into a funnel?

In the earliest cylindrical filter cup, the actual extraction area that can be used in extraction is actually the same as the bottom area. Because the extraction area of the cylinder design is narrow and the extraction time is relatively long, in order to avoid bad taste and uncomfortable sour taste of coffee, it is necessary to shorten the extraction time, but if you want to shorten the extraction time, you must first increase the surface area that can be extracted.

Making use of the characteristic that the water will extend around when the water is still, the filter cup will be made into a funnel shape, so that the side can also extract coffee, and the extraction area will be much larger than that of using only the bottom, and can be extracted more quickly. In this way, the improvement can reduce the bad taste caused by extraction for a long time.

Why is there a rib groove (rib)?

If you look closely at the inside of the filter cup, you will find that there is a long protruding line on the inclined wall, protruding the cup wall at a certain distance. It is called rib because it looks like a rib.

If you want the extraction on the side of the filter cup to proceed smoothly and shorten the extraction time slightly, the filter paper on the side must be separated from the wall of the filter cup. In order to create a distance between the filter paper and the cup wall, a ribbed groove was made on the cup wall. The ribbed trough allows the air to flow smoothly, providing space for the water to flow through, and the water can flow down more easily.

If the filter cup is different, will the taste be different?

Even for products made by the same company, the coffee extracted from the plastic filter cup and copper filter cup of the well-known Japanese brand Kalita has a 30% difference in speed, so the taste is also different. This is because the filter cups made by each company are different, the coffee powder is piled up differently, and the extraction speed is also different. The appearance of each filter cup has something to do with the speed at which the water falls. The faster the water falls, the less aroma the coffee dissolves, and the slower the water flows down, the more aroma the coffee dissolves. Therefore, if the water injection speed is the same, the taste will be slightly different according to the type of filter cup.

If you use water easy to fall, the filter cup with faster extraction speed will not be affected by the miscellaneous smell that will occur during slow extraction, and you can get lighter and lighter coffee. If you use a filter cup with slow flow rate and long extraction time, because the extraction speed is slow, the advantage is that the aroma and taste will be more profound, but if the extraction time is too long, the miscellaneous smell will also become more.

Velvet filter screen

A flannel filter is a filter made of cloth, usually made of flannel. Flannel is made of cotton and brushed with an iron brush, so that the surface of the cloth is covered with a layer of fluff. After the cloth is cut into triangles or semicircles, three pieces of 2Murray are formed.

Compared with the filter paper made of paper, flannel is less compact and meticulous in organization, so there is a large gap between tissues. Compared with filter paper, flannel allows coffee flavor ingredients to flow out more smoothly during coffee extraction, because of this property, coffee extracted by flannel will be richer and milder. And because it is conical, when coffee is filled, the specific gravity of coffee concentrated in the middle is higher than that of other filter cups, and when the same amount of coffee is filled, compared with ordinary filter cups, it can make coffee accumulate deeper, and because of this, the distance of water through the coffee will be longer and the taste will become richer.

However, the oil in the coffee will be adsorbed on the filter during the extraction process, so it should be well maintained. If it is not properly handled and left on the filter, the coffee residue will turn sour and bad and may produce a bad taste. Rinse with running hot water immediately after the extraction to remove oil and residue as much as possible. Water should be changed about once a day to prevent pollution. If it is not used for a long time, it can be stored in a plastic bag in the freezer, or after it is completely dry, it is a good method. Sometimes it can also be boiled in boiling water to reduce the change of taste.

When extracting coffee, the residue and oil will accumulate in the tissue of the filter, which will slow down the extraction speed and dissolve a certain degree of taste every time you use it, so the more you use it, the worse the taste will be. You will feel the change in taste after using 20 Murray for about 30 times. if you find that the extraction speed is obviously slower or the taste is worse, you should replace flannel.