A new espresso brewing method

Abstract A new espresso brewing method has recently been developed. The main steps are: introduction and tamping of ground coffee in a sealed chamber, introduction of pressurized air into the chamber, the introduction of hot water and a pre-infusion phase. It is substantially different to the usual brewing method used in bars: the driving force for the flow is the pressure difference between the interior and the exterior of the chamber (rather than pressurized hot water provided by a motor-driven pump); the extraction process is partially static; the pressure is higher than the traditional method; and the temperature of the extraction chamber can be controlled (in addition to the water temperature control found in the traditional method). The method has been tested with three chamber temperatures and two pressures. At all settings, espressos produced using this method have particularly high and persistent foam. Furthermore, changes in pressure cause changes in some physical parameters and the amount of key odorants in the headspace above the coffee. A benchmark comparison with the capsule method gives differences in several aromatic compounds and in almost all the physical parameters. In conclusion, the beverage produced by the CF method is clearly recognizable by a thick and very persistent foam layer, while the method appears more flexible than the traditional one as the characteristics of the EC can be adjusted as a function of brewing conditions.