During the steaming process, the bubbling of the powder bed may be caused by the fine powder clumping or uneven water injection, which is easy to form a channel effect and lead to uneven extraction.
The "channel effect" occurs because the inertness of the water makes it easier for the water to pass through, ignoring other routes, and the water rushes through the cracks in the coffee press, resulting in thin and underextracted espresso. When this happens, a yellowish streak is often seen in the liquid running down from the coffee, and sometimes the channel effect can leave a pencil-lead sized hole in the powder.
There are several main reasons for the formation of channel effect.
What causes the "channel effect"?
- Repeat powder placement
When the number of grams of powder is not enough, the powder is taken several times,
But if you have to repeat the powdering action after each collection,
Then your powder layer will appear "light at the top and heavy at the bottom,"
The channel effect occurs when the density is not uniform.
2. Take the powder without drying the bowl
The water stains in the bowl will cause the coffee powder to clump,
Naturally, the coffee powder at the edge of the bowl presents an uneven state.
3. The handle is too hard into the boiling head
The pounding sensation caused by too much force
It is not only easy to crack the inside of the coffee powder layer to form a channel;
And the degree of damage to coffee is also affected.
In the next article, I will highlight some ways to avoid channel effects.
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