Channel effect? On the Channel effect in Coffee extraction

Today, I'm going to talk about the channel effect. when I first learned about the channel effect, it was not long before I made coffee, and the coffee powder could not be well distributed in the powder bowl. My teacher often told me that your coffee has a "channel". At that time, just according to the gourd painting ladle to figure out some superficial things, what is the difference between them, is with the continuous learning to realize.

So what exactly is the channel effect?

Because water is inert, it will choose the path with the least resistance when it passes through the coffee powder.

Espresso1: its coffee powder is evenly arranged, and it can be evenly extracted by water when it is extracted by a coffee machine.

There are gaps in the arrangement of espresso2 coffee powder. When extracted by a coffee machine, water will choose to pass through more empty places, while coffee powder in some places will not be extracted by water, resulting in excessive extraction of some blocks with more water and insufficient extraction with less water.

Q: so what is the cause of the gap in espresso?

Bean grinder: bean grinder due to the grinding uniformity / shape is too low so that the coffee powder can not be very well together, there are large and small coffee powder.

2. The process of powder distribution: some of the processes will also cause channels. For example, there are obvious holes in the surface, or after filling and pressing, it is found that there is not enough powder to continue to add powder, and so on. All these will cause the uniformity of pressed powder to become lower and form a channel.

Q: but does the channel effect only occur in espresso?

A: in fact, we are also prone to channel effect during hand flushing, such as injecting water to the edge of the border between filter paper and coffee, causing the injected water to flow directly through the filter paper to the sharing pot after passing through the coffee. or in the water injection circle when there is no uniform circle, the injection point is on one side, will also lead to the occurrence of the channel.

There is a significant difference in flavor between the coffee extracted by the channel effect and the coffee extracted normally, and the channel effect still needs to be avoided by ourselves in our daily work.