Recently, a colleague who has just come into contact with pour-over coffee asked why every time he makes pour-over coffee, he needs to pour the coffee powder in hot water and steam it, and then continue to pour water after half a minute to one minute? This action is generally called for "presoaking" or "steaming". The presoaking process occupies a very important part of the coffee extraction process. A good presoaking can fully infiltrate the coffee powder, thereby making the subsequent coffee extraction process more smooth.

I don’t know if any friends who are new to pour over coffee have the same questions as our colleagues. This article will take you an in-depth understanding of what exactly is prepreg, what is the function of prepreg, and what effect does it have on the quality of coffee extraction.

The word presoak is translated as Bloom in English, which refers to the process of evenly moistening the surface of coffee powder with a small amount of hot water before the formal extraction so that the coffee powder releases carbon dioxide.

What is the effect of prepreg?

1. Release the carbon dioxide in the coffee powder. If most of the carbon dioxide gas in the coffee powder is not discharged before the formal extraction, the result of uneven extraction will be produced.
2. Pre-soaking can soak coffee powder, while moistening the coffee powder, open the honeycomb holes in the coffee powder to release the coffee flavor.
3. Pre-soaking can form a stable structure and gap between the coffee powder particles, which facilitates the stable passage of water in the later stage, and can also prevent the appearance of unpleasant odors.

Seeing this, I believe many friends will ask, what will happen if the coffee extraction is less pre-soaked?

If the pre-soaking process is omitted during the hand-punching process, a large amount of hot water will quickly pass through the powder layer. Not only will the structure be washed away, but the coffee powder will also be incompletely soaked so that the dripping time will be prolonged. This results in partial under-extraction and partial over-extraction.

So, here comes the question,

Which links will affect the effect of coffee prepreg?

1. Filter cup and filter paper

A good filter cup and filter paper are not only necessary tools for making good coffee but also necessary for good pre-soaking.

The grooves of the filter cup design of the high-quality brand can make the air flows better so that the carbon dioxide gas is better released. At the same time, the air and water permeability of the high-quality filter paper will also allow hot water and steam to pass through quickly, and will not appear during the prepreg The phenomenon of over-extraction.

2. Water volume

The ratio of steamed water to coffee is between 1-2 times that of coffee powder, that is, 20g of beans are steamed with 20-40ml of water. If the amount of water is insufficient, the extraction will be insufficient, and the coffee will not be soaked enough; if too much, it will be extracted in advance, resulting in an unstable structure of the mushroom bag.

3. Time

The pre-soaking time can vary from half a minute to one minute, depending on the freshness of the coffee and the dehydration of the coffee beans. If the pre-soaked mushroom bun collapses early, the soaking time needs to be shortened.

Finally, add some common sense and myths about coffee prepreg

1. Coffee pre-soaking is not the key basis for judging the quality of coffee. The pre-soaking of coffee has a great relationship with the thickness of the grind, coffee roasting time, and roasting degree. Not all coffee must-have mushroom buns to be good, but if there are no mushroom buns with coffee beans that have been stored for a long time, then the coffee pre-soaking time should be shortened appropriately.
2. The coffee pre-soaking method needs to be gentle, and the water flow should not be too high when filling water, to avoid the structure of the coffee to disperse the coffee and make it taste bad.
3. The temperature of the coffee pre-soaking water should not be too high to avoid bitterness, nor should it be too low, so that the water cannot completely infiltrate the coffee powder, resulting in incomplete extraction.
4. Of course, some people will dig a hole in the middle of the coffee, and then diffuse to the middle to make the extraction more fully. The coffee powder can be spread flat, and there is no need to pay too much attention.