What is the reason for water accumulation in the perforation of the espresso perfect powder? How to solve the problem of agglomerating espresso powder

A major problem in making Italian concentrate is that we have to constantly adjust parameters such as powder amount, grinding thickness, and ratio to improve the quality of coffee so that it can achieve an ideal extraction process within tens of seconds. In addition to observing the flow rate, pressure and extraction time, the extracted coffee powder can also provide us with useful information.

Let's first take a look at what an ideal powder cake looks like:

Just like the powder pit of hand-brewed coffee, the uniform and round bowl-like structure means that the water injection technique passes and the grinding is not disturbed. For espresso, because pressure-assisted hot water extraction is used, a large amount of soluble substances can be brought out in a short period of time with very little water. At this time, observing the extracted powder cake becomes a judgment. One of the visual criteria for whether there is a problem with espresso coffee.

Normally, after the extraction, the best state of the powder cake is first relatively dry, with a flat surface, no water or obvious holes, and when knocked out, it is a complete block with uniform color distribution, consistent thickness and not easy to break. But if your powder cake is difficult to form and the coffee always tastes unsatisfactory, Qianjie recommends combining these two aspects to find out the problem.

1. The surface of the powder cake is potholes

It can be said that both experienced baristas and newcomers who have just started out have encountered this situation more or less. The surface of the powder cake is potholed, indicating that the hot water did not get enough space for exercise during extraction. One of the reasons is that the powder cake is too thick.

Under normal circumstances, the lighter the roasting degree, the smaller the volume expands, and the deeper the roasting degree, the larger the volume. Therefore, under the same weight, the powder cake of the deep-roasted beans will be thicker. After absorption and expansion, it will be too close to the water distribution network. The coffee particles adhere to it, and when the handle is removed, an uneven surface layer will be seen. At this time, the coffee is often accompanied by insufficient extraction and has a light or sour taste.

Solution: Thinning the powder layer by fine grinding + reducing powder.

2. The powder cake has holes

Perforation is a prominent feature of the channel effect, because water is inert. Once the density of the cake is unevenly distributed, it will pick loose places and drill through it. At this time, the extraction efficiency is higher where hot water flows through. In other places, insufficient extraction will occur, and sometimes splashing and flow rate jumps will occur.

Solution: Pay attention to cloth powder (break up the clotted coffee)

3. Serious water accumulation in the powder cake

Contrary to the first situation, this water accumulation problem is mainly caused by too thin the powder layer, and the problem generally lies in the degree of abrasion. Even for the same coffee bean, when the grinding degree is adjusted to be finer, the gap between particles becomes smaller and the density is higher, so the height of the powder layer will drop. If the same powder bowl is used, a larger space will be formed between the powder cake and the water distribution net, and the hot water will stay on it for a longer time, and serious water will appear on the surface of the coffee grounds.

There is also a situation on a coffee machine, which is 9 bar atmospheric pressure, because we need to meet at least two conditions to obtain espresso rich in coffee grease. One is fresh medium and deeply roasted coffee beans, such as Qianjie Boutique blending, Qianjie Commercial blending, and Qianjie Classic blending are all Italian recipes that help us easily extract qualified espresso at home.

The second key point is the hardware equipment. Many home users 'coffee makers almost belong to the category of "toy machines." It is difficult to reach 9 atmospheres of pressure when operating, and even make a clicking sound. If the penetration is insufficient, it is naturally difficult to achieve deep extraction. In addition to stopping on the powder cake, the coffee liquor may also flow down.

Solution: Roughing and grinding + adding powder

4. After extraction, the powder cake is loose, moist and soft

Compared with the ideal powder cake mentioned at the beginning of Qianjie, the loose or moist and soft state indicates that hot water extracts the coffee in a shock-type manner, and each particle becomes sticky because it is full of water. The flow rate in this case is generally within the normal range (powder-to-liquid ratio 1:2, time 25 - 35 seconds), but it will be more bitter when drinking. The reason behind this is mainly caused by too little coffee powder. If you also have this kind of problem, you can try adding 0.5 - 1g coffee powder.

In addition, if you use double powder bowls to make a single shot with half the powder amount, it is easy to have such problems. It is recommended to replace it with a single powder bowl.

Solution: Add powder/replace single powder bowl

5. The powder cake is dry while it is wet

This situation is very simple. When pressing the powder, the center of gravity for applying pressure is not grasped well, resulting in uneven heights of the powder cake. Qianjie usually presses one side of the powder hammer with the thumb and index finger, and then the remaining three fingers cooperate with the palm to wrap the hammer handle, the arm is vertical, and then presses downward with force.

6. The bottom of the coffee cake is black

During the Italian concentration extraction process, hot water penetrates from top to bottom, reaching the surface of the cake first and finally the bottom. A evenly extracted "good cake" usually has a consistent color from the inside out, but if you remove the handle in advance, the flavor substances in the lower layer may be forced to end the extraction before they can be released, so that the bottom will be black and semi-moist, and the coffee will taste thinner due to the lack of the tail segment.

Solution: First extract according to the powder-to-liquid ratio of 1:2. If the extraction time is too long, adjust the coarse grinding degree.

FrontStreet Coffee is a long-established specialty coffee roaster in Guangzhou China, selling freshly roasted beans from its own farm in Yunnan as well as dozens of carefully selected single-origin beans from around the world for both pour-over and espresso. The products deliver consistently excellent quality and great value, with shipping within 24 hours. Guangzhou’s FrontStreet Coffee shop is recommended by many coffee lovers, and the beans are now available online at the Tmall 。

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473