Italian condensed knowledge of Espresso prepreg method and principle

Pull rod prepreg has existed since the birth of espresso, and it is not a new thing invented in modern times. For the earliest pull-rod machines, the prepreg function was natural. When making coffee, pull down the pull rod (lever), lift the piston, the hot water enters the cavity and the filter bowl, and the hot water touches the coffee cake and begins to presoak, and the pull rod is not released until the desired pre-soaking time is completed. The piston begins to press down under the action of the spring to realize the extraction of coffee. By the way, the pull rod machine does not need to relieve pressure, because when the piston reaches the bottom of the cavity, the pressure of the spring is already very small.

E61 when the working mode of the pump driven by the motor replaces the working mode of spring and piston, the pressure relief will be opened after it is finished.

B) after pressing the production key, the pressure relief cutting is turned off until the coffee is made, and the water pump is operated briefly (when the hot water entering the filter bowl is less and the pressure is low), then pause until the prepreg is completed, and then start running again until the coffee is finished.

Hand-controlled version of the manual version of the prepreg how to do? Experts do not advocate the manual way of "on-off-pause-on". In fact, the pressure of the pump is not established instantly, coupled with the fact that the water pipe entering the boiling head is very thin (or has a very thin section) and has a flow-limiting effect, so the water pressure in the filter bowl is also established step by step, and there is no need for artificial prepreg.

In fact, no matter which way of pre-soaking, the hot water is only in contact with the thinnest layer of coffee powder on the surface of the coffee cake in the filter bowl, not the whole coffee cake.