Effect of presoaking (steaming) on Coffee extraction

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ESPRESSO PREINFUSION

Concentrated pre-soaking

The pre-steaming of espresso is similar to that of hand-brewed coffee. Ideally, the pre-soaking of espresso will take place at zero pressure and low flow rate (for example, 2-3ml/ seconds), and the pressure to extract coffee will not increase until the entire coffee pressed powder is wet.

Like pre-steaming, low-pressure water for pre-soaking can allow water to enter all coffee powder in the powder bowl before high-pressure extraction of soluble substances in the coffee bowl, thus improving the uniformity of the extraction. The preleaching of espresso also reduces the migration of fine powder and reduces the occurrence of channel effect, regardless of whether we use finer grinding or not, and will slightly increase the extraction rate.

PREWETTING AND IMMERSION BREWING

Pre-immersion and immersion extraction

But again, pre-steaming may be meaningless for immersion coffee extraction and may be counterproductive. Do an experiment: make two cups of kettle with a powder-to-water ratio of 1:17 and 95 ℃ of water, one of which is added to the pre-soaking process and the other is not added. The total contact time for two-cup extraction was 4:30. In the pre-steaming process, some coffee powder will be soaked by fresh and clean turbulent water. Other coffee powders on the edge are wetted with saturated liquid.

Coffee powder that comes into contact with water first will be extracted more completely, resulting in uneven extraction. However, if the pre-steaming process is abandoned in the immersion extraction process, and all the water is poured into the coffee powder, then all the coffee powder will be moistened, soaked and extracted at the same time by the same temperature and concentration of water to improve the consistency of extraction.

However, this is not to say that immersion extraction cannot extract good coffee if pre-steaming is added. However, like most coffee extraction techniques, the question is not whether a good cup of coffee can be extracted by one method, but which method can extract a good cup of coffee most reliably. The two basic principles of good coffee extraction are: 1. To achieve the most uniform extraction; 2. More substances are extracted within the expected extraction range. According to these standards, pre-fogging is beneficial to trickling extraction, but not to immersion extraction.