When it comes to coffee tamping, there are many things that we should take into consideration.
Why should we tamp coffee and why is it important?
When you go to cafes, you will see every barista tamping the coffee before the extraction, why is that?
There is an important concept of when it comes to tamping coffee. When brewing the coffee espresso, the coffee machine would impose a high pressure (usually 8-9 par) on the coffee powder. Due to such high pressure on the coffee powder, if the coffee powder is too loose, the water would drip through too quick (overall timing that water touches coffee is shorter), therefore the espresso would be under extracted.
Thinking about the water flow through sand & rock in this way, that if water flow through a pile of rock, it would be so quick, but if water flow through sands, then it might take a while.
By tamping the coffee powder, each particle would be close to another, thus giving more time for water to brew through, and therefore a better taste.
Distribution of Coffee Powder
Making sure that the coffee powder is evenly distributed inside the group handle basket is also important. An uneven distribution of coffee powder would cause the espresso extraction uneven.
For example, if the coffee powder is not distributed at all, then one side of coffee powder would be higher than the other. When same pressure is imposed on the basket, one side of the extraction would be quicker than the other, thus cause the the espresso sour and bitter.
In such case, baristas usually use some tools like coffee distribution tool to help them making sure each espresso is exactly the same. Another way of distributing the coffee powder is to use the hand:
- Get coffee powder from the grinder and make sure it is piled in the middle.
- Put your hands on top of the pile, with the center of your palm hold the pile.
- Gentlely spread the coffee powder and twist your hands until it is even.
What is the right tamping pressure?
By default, we impose 10kg of tamping pressure when tamping the coffee powder. This would usually give a great result, making sure the coffee powder particles are tight to each other. However, there is no stress out an exact 10kg pressure, as we cannot measure how much pressure exactly on the basket (unless a tamping machine like PuqPress) As long as we remember to tamp the coffee each time, it would usually give a great result.
The Bottom Line
In conclusion of the above, it has been proved that tamping coffee correctly, doing the right distribution would help you to get a nice espresso, but never be too stressed to measure the tamping weight each time, as it doesn't make too much difference if it is 1-2kg more or less.