Variable pressure! Pressure curve Pressure Profiling of pressure swing extraction of espresso

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The term Pressure Profiling, or Pressure Profile (s) (pressure curve), was invented with the development of Italian coffee machine manufacturing technology. it is the result of baristas breaking through the traditional extraction method and introducing new controllable variables. it is also a new tool that can not be missed by a new generation of baristas who pursue the flavor of the third wave of coffee production.

When it comes to the pressure curve, we must first explain the meaning of this term: in the set extraction time, the curve formed by the change of extraction pressure with time is called the pressure curve.

The traditional view is that espresso is extracted at a constant pressure of 9 atmospheres, which has something to do with the setting and purpose of the original espresso machine when it was invented, when Italians wanted to get it as quickly as possible when they entered a coffee shop to buy a cup of coffee, rather than relying on the way that the mocha pot had to be heated by the stove, because it took too long to wait. So the espresso machine was invented under such a time and space background, the brewing time was greatly shortened by high-pressure extraction, and a cup of coffee could be completed in 20-30 seconds, which is also the origin of the word Espresso. Since the advent of the Achille Gaggia modified coffee machine and the well-known Faema E61, the structure of the brewing pressure has not changed much, and the world's major coffee machine manufacturers (mostly based in Italy) are committed to making the pressure more stable rather than changing it.

Italian coffee machine with variable pressure

In the past five years, variable pressure espresso machines have been invented one after another. La Marzocco, Slayer, Synesso and other manufacturers have published high-end models with variable pressure. Although the introduction of variable pressure often makes Barista the first two big, it also creates unlimited possibilities. Different pressure curves do produce great changes in flavor. In the past, the flavor can only be adjusted by water temperature, powder quantity, grinding thickness and other factors. After the pressure curve is added to the lineup, it gives the coffee shop of the third wave a new opportunity. The third wave of coffee emphasizes the light and medium roasting degree to bring out the flavor of the coffee producing area, but also because the shallow roasting degree leads to the weak oil and viscosity of the coffee, it will be more difficult to extract the espresso (that is, Single Origin Espresso, single espresso) with only beans from a single producing area and correct it to the ideal flavor. The setting of the front section of the pressure curve (slow pressure gentle pressure ramp or sharp pressure swift pressure ramp) combined with the adjustment of grinding thickness really gives the coffee more possibilities.

If the coffee machine you come into contact with or use does not have a variable pressure control valve, usually large commercial or middle-class Italian coffee machines also have the function of pre-immersion pressure (pre-infusion), sometimes enter the system setting, some are manually controlled, by adjusting the number of seconds of pre-immersion pressure and the total extraction time, you can also try a completely different coffee flavor, these are different "pressure curves". It is suggested that you can try in many ways, so that the majority of coffee drinkers can have more different flavor experiences.