[illustration] hand-made coffee injection course how to fill water by hand and how to circle it

A few days ago, a guest came to the shop and asked, what are the requirements for hand brewing coffee? Is there any attention to the height of water injection?

customary injection height

When asked how high the water column needs to be when injecting water, he instinctively froze!!! Indeed, there is no precise standard. Some people like to stick to the liquid surface when pouring coffee, while others like to pull up the water column. If there is a range, it is about 0-7cm. The requirements for water injection in the front street are very simple. The water column is vertical, stable in circles, and the water column hits the water surface without bubbles.

What is the best injection height?

According to the water injection requirements of the front street, it is difficult to ensure that the water column is vertical and the water surface is bubble-free at the same time. (When the same water flow, slowly pull up the water column to reach a threshold, the end of the water injection will become a water chain, so that the liquid surface will bring bubbles into it, so you can only increase the flow rate, but the design of the hand-flushing pot, the water flow will appear arc, that is, not perpendicular to the liquid surface)

As for how high the injection should be, we introduce a new question: how much can high water column and low water column change the flavor of coffee?

There was an experiment done on this front street. Coffee was brewed with water injection heights of 2 cm and 10cm respectively. Other parameters should be consistent as much as possible. The result is that water injected closer to the coffee level produces a stronger coffee and a stronger aroma than water injected farther away.

In the past, it was believed that the higher the water column, the stronger the impact force of the water column and the stronger the stirring ability of the water column. According to understanding, the higher the water column, the higher the extraction ability and the higher the concentration. But the experiment showed the opposite.

The reason is that the impact force is much less affected than the temperature. Due to the high water column in the process of injection, a large area of exposure to the air, resulting in faster cooling than low water column, although the stirring ability is stronger than low water column, but due to the lower temperature injected into the coffee powder, resulting in slower dissolution of coffee substances, and because of the strong stirring force, the speed of water will also be faster. So the coffee will be slightly less strong.

Maybe you already know how to fill it up.

Therefore, we know that when brewing, the height of the water column will affect the actual extraction temperature. No matter how high the water injection is, it is not too big a problem. What is important is the brewing parameters that match it. For details, you can refer to the Japanese Matsuya style brewing. When you see the 30cm high water column, you will feel shocked, but when you really understand the whole brewing scheme, you will sigh at the compromise made by the conditions at that time.

Just as the front street brews medium and shallow roasted coffee beans, it is customary to brew the water temperature of 91℃ with the water injection height of 4-5cm, which is the coffee flavor that the front street wants (of course, depending on the grinding degree, powder-water ratio and other parameters).