What do you mean by pre-soaking? The principle and method of pre-soaking and the length of pre-soaking time

Whenever we develop an extraction framework for hand-brewed coffee, we will cover steaming by default. The ideal steaming allows the orderly discharge of carbon dioxide, while "awakening" the soluble substances in the coffee, making the subsequent flavor extraction more stable.

Since steaming has such a great impact on the flavor of coffee, do you also need to add steaming in other brewing methods, such as the most common Italian coffee extraction?

What is the name of "steaming" of espresso? The conventional Italian concentration is usually extracted continuously under the pressure of 9bar until the end. In this way, as long as we press the extraction button, the hot water passes quickly through the coffee pressed powder at about 9 atmospheres, bringing out the soluble flavor substances. If the coffee machine formally applied full-pressure extraction, first put water in the form of no pressure or low pressure, the hot water gently infiltrated into the coffee powder layer, the step of uniform wetting, is called "pre-soaking".

The first prerequisite for the application of pre-soaking is that the coffee machine itself can support this function, and its mode of operation will vary according to the type of device. Some coffee machines can set the "one-button pre-immersion" mode before extraction, while others need to adjust it manually.

The duration of the pre-soaking stage and whether pressurized or not mainly depends on the barista's understanding of the flavor of the beans, combined with the state of bean cultivation and the collocation of extraction parameters, so there is no standard fixed parameters.

Under what circumstances do you need to apply pre-immersion? When we grind and extract the Italian coffee beans just a few days after roasting, in the environment of high temperature and high pressure, the overactive carbon dioxide will "run around" at the moment of water, and then these gases will wrap the coffee oil to form a thick Crema (oil), which will flow out quickly with the coffee liquid.

This concentrated oil, which is too fresh bean extract, looks so rough and unstable that it dissipates and decomposes in a few minutes, and the flavor of the coffee is light or sour. Then in order to solve the trouble caused by the abundant gas of coffee beans, we can add the action of "steaming", that is, pre-soaking, just like hand flushing.

For example, sometimes the date of warm sun mixed beans received by Qianjie stores is too fresh to be used for production before it is too late to grow beans. Espresso directly extracted usually shows a strong sour feeling and uncomfortable bitter rhyme, completely missing the original aroma of fermented wine and sweet and sour fruit. At this time, Qianjie will combine the adjustment of the grinding degree and the ratio of powder to liquid, and add the step of pre-soaking during debugging, hoping to "stabilize" these gases and better handle more coffee flavor.

In addition to dealing with the exhaust problem of "new bean", pre-soaking can also reduce the probability of channel effect during extraction. If we do not fill the coffee pressed powder evenly and directly impact it with 9bar water during extraction, then the water column can easily break through the weak position and form a channel effect. If the powder layer is wetted in advance to allow the particles to absorb water and expand, pressed powder will become denser, the flow is not easy to "steal", and the contact between powder and water will be more stable.

Try pre-immersion extraction here, Qianjie take the equipment and Italian beans used in your own store as an example, simply try the application of pre-immersion extraction. Coffee beans are made up of warm sun for 22 days. The coffee machine is a Lelit Bianca V3 that supports pre-soaking function. When you use it, you need to manually control the pick to change the extraction pressure and the flow rate of water.

Pre-immersion on the left and constant pressure extraction on the right

Direct extraction without pre-immersion: 20 grams of coffee powder, the first drop of coffee liquid flows out in 6 seconds, the liquid weight is 38 grams, the total time is 27 seconds, the flow rate in the latter stage is relatively rapid.

Espresso: fat fluffy, slightly rough, taste balanced, aromas of nuts, citrus acid, vanilla, with a hint of caramel in the finish.

Use pre-immersion extraction: 20 grams of coffee powder, low pressure water 15 seconds (pick moved to the leftmost, aligned with the handle), 8 seconds to produce coffee, 16 seconds pressurized to 11bar (pick moved to the right, a 90-degree angle), extraction 38 grams of liquid weight, the total time is 34 seconds, the whole flow rate is slow.

Espresso: the fat is dense and delicate, the aroma of whisky and chocolate biscuits is obvious, the acidity is light and upward, similar to cherries and berries, and the mouth is as sweet as preserved fruit after swallowing. Even if it is directly concentrated, it is also good to import.

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Front Street Cafe

No. 10 Baoqian street, Yandun road, Dongshankou, Yuexiu district, Guangzhou, Guangdong province