Introduction to the course of making Italian Coffee: a brief introduction to the details of steaming and presoaking

Steaming and pre-soaking are the first stage of the extraction of single hand-brewed coffee and esp. The quality of steaming and pre-soaking directly affects the taste of a cup of coffee. Although they are used in two kinds of coffee with different production processes, they have a very close relationship and the same principle.

Steaming and pre-soaking:

Steaming:

It refers to the process of sprinkling hot water gently, softly, quickly and evenly on the coffee powder when making hand-brewed coffee, which is a process of "activating" the coffee powder and forming an upward uplift.

Prepreg:

It refers to the process of quickly wetting the surface of the coffee cake in 1-2 seconds when making esp.

To sum up, steaming and pre-soaking are both a process of wetting coffee powder before making it.

Why are the two closely related and have the same principle?

Let's first talk about the role of the two:

one。 Steaming:

When making hand-brewed coffee, most people pay a lot of attention to the softness of the current and the freshness of the coffee powder, and steaming is also indispensable. Good steaming can fully infiltrate the coffee powder and activate the coffee activity, thus making the coffee extraction process more smooth. The so-called activation is to make the coffee powder have a bulging state similar to a volcanic eruption. the coffee powder rises upward, the air between the coffee particles will be heated and expanded, and the coffee particles themselves will release a large amount of carbon dioxide. bubble-like voids are formed between the particles, which make the coffee powder form a uniform filter layer to provide the space needed for hot water to pass through.

The voids formed by good coffee steaming are approximately uniform, and the flow rate of coffee liquid filtered downward is also uniform. If a good filter layer cannot be formed, then a full penetration of water will be formed, the filtration rate will be slowed down, the extraction time will be prolonged, and then the phenomenon of excessive extraction will be formed. Coffee taste will also be messy, sour-based, coffee itself is difficult to reflect, the taste is thin, with irritation, and the aroma is not dignified enough.

So what are the influencing factors of steaming?

The first is the choice of instruments for production. Good filter cups and filter paper are not only necessary for making good coffee, but also necessary for good steaming. The high-quality brand filter cup design groove can make the air fluidity is good, will not let the gas gush out from the coffee surface, the water permeability of the high-quality filter paper will also make the hot water pass through quickly, will not form the dripping filtration speed sometimes fast and sometimes slow.

Second, it is necessary to have a suitable hand flushing pot, which can well control the outlet speed and flow rate, flow rate, as well as the softness and hardness of the flow.

Third, water quantity. Steaming water does not need too much, only need to wet the surface of coffee, but need to be soft and light, fast and uniform, like spring rain moisturizer, so that the steaming speed can be carried out at the same time.

Fourth, the temperature of the water. I personally think that the best temperature for making hand-brewed coffee is 83 degrees, and the highest temperature should not exceed 90 degrees. This kind of water temperature will not produce too much bitterness or sour taste when steaming, and it can also make the coffee fully expand.

Fifth, the time from the beginning to the end of steaming. I personally think that steaming really doesn't take as long as the theory, and the most important thing is to observe the state. Starting from the expansion uplift, the best first water injection time I personally think should be the best water injection time before the expansion reaches its maximum, but before it stops expanding. If the expansion reaches the maximum, stop the expansion and then inject water, the gap formed will be so large that it will be collapsed by the sudden flow of water and cannot be fully extracted.

The state and taste of a cup of hand-brewed coffee depends largely on whether a good filter layer is formed, that is, whether steaming is sufficient and good, and the greatest significance of coffee extraction is to let hot water evenly pass through the coffee powder.

two。 Pre-immersion.

Prepreg is a subject that takes place in the production of esp.

Prepreg occurs within 1-2 seconds after pressing the extraction key, which is so short that it seems negligible, but what happens in this 1-2 seconds affects the subsequent extraction state, that is, the taste of coffee.

What is the function of prepreg?

In fact, pre-soaking and steaming are roughly the same, that is, wetting the surface of coffee, making coffee pressed powder expand rapidly, making pressed powder form a good filter layer. In theory, the expansion space of coffee powder is about 1-2mm. The expansion makes a uniform bubble gap between coffee powder particles, so that water passes through quickly and evenly. The function of prepreg 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.

So what are the influencing factors of prepreg?

Apart from other production factors, such as pressing powder, grinding, and so on, the first factor affecting prepreg is the filling amount of coffee powder, which, of course, refers to the filling amount after pressing powder. The perfect filling volume is below the filling line of the handle, the handle card is washed on the head and then taken off, pressed powder without any trace is qualified, then what is excellent? in theory, the perfect filling amount is that there is a gap of about 1-2mm between the surface of pressed powder and the outlet network of the head, which happens to be reserved for coffee powder and used as a space for physical expansion.

The second is pump pressure. A stable pump pressure is a necessary condition for making good coffee, and of course it is also necessary for pre-soaking.

Third, water temperature. The water temperature in the pre-soaking stage is preferably between 95 and 93 degrees, so that the coffee will not be too bitter.

In conclusion, whether it is pre-soaking or steaming, it is to make the coffee physically expand, form a uniform void, and then form a good filter layer, so that hot water can pass through quickly and uniformly, without excessive blocking, resulting in excessive extraction. and then a process of full extraction.

Source:

Happy Coffee Xiao Xu's blog