What's the difference between pre-soaking and steaming? Does immersion extraction require pre-soaking?

We usually have a step in making hand-brewed coffee-steaming, especially in brewing with a filter cup, so do we need to add steaming or pre-soaking to the coffee extracted by immersion?

Steaming and pre-soaking

Steaming and pre-soaking are similar, but what's the difference?

Stuffy steam

It means that when making hand-brewed coffee, the hot water is placed gently, softly, quickly and evenly on the coffee powder to "activate" the coffee powder and release a large amount of carbon dioxide, and the coffee powder will form a process of uplifting upward. That is to say, steaming is actually a process of letting coffee powder emit carbon dioxide.

Pre-immersion

It is a process of quickly wetting the surface of a coffee cake with water. In fact, pre-soaking and steaming are roughly the same, that is, wetting the surface of coffee, so that coffee pressed powder rapidly expand the emission of carbon dioxide, so that pressed powder to form a good filter layer, in theory, the expansion space of coffee powder is about 1-2mm, expansion so that coffee powder particles to form a uniform bubble space, so that water quickly and evenly through. The function of pre-soaking is to expand between these coffee particles, forming a uniform size gap, so that the aroma of coffee can be released as much as possible.

Whether it is pre-soaking or steaming, it is to release gas from the coffee, avoid hindering the extraction in the follow-up process, and form a uniform void, thus forming a good filter layer, so that the hot water can quickly and evenly contact the powder bed without excessive block. an important process of excessive extraction and then full extraction.

We all know that if there is no steaming, the brewed coffee will taste lighter. (portal: what would it be like without steaming? What's the use of steaming? ) so in the process of soaking and extraction, how much is the effect of pre-soaking on the flavor?

So today we use the Philharmonic pressure reverse pressure way to try, whether the pre-soaking has how much impact on the flavor? We chose [Sidamo Candlestick] [Yemeni Mocha] [Costa Rica Pilon treatment Plant] to extract by pre-immersion and direct water injection respectively to see what the difference would be.

In fact, in terms of flavor, with or without pre-soaking is quite similar, but with the addition of pre-soaking, the drink will be lighter than that of direct water injection, and the fruit acid is more obvious. The editor guessed that this was because the bottom of the Philharmonic pressure was flat, only a small amount of water was given to wet most of the powder bed during pre-immersion, but it was not guaranteed that all the powder and water would be in uniform contact, so there would be some lack of moisture that led to uneven extraction in the later stage, and the water column directly played the role of stirring when the large current was injected with water at one time, allowing the powder to fully contact with the water for extraction.

Take Philharmonic pressure as an example, the editor feels that it is not necessary to add the step of pre-immersion, and it is also possible to directly inject water and stir with water flow, but if you want to add this step of pre-immersion, you might as well stir it with a stirring rod. so that all the powder can be extracted evenly.