Pressure Profiling
Pressure profiling espresso machines are designed with ultimate coffee connoisseur in mind in order to provide the best depth of flavor to espresso as possible. Pressure profiling machines vary pressure during extraction to get different flavors from each level of pressure during the extraction process. Most pump driven espresso machines are designed to go up to a certainly level of pressure and stay at that level of pressure during the entire extraction. As an example, a pump driven espresso machine will generally extract around 9 bars of pressure. When the brew cycle is activated, the pump will apply pressure and if the grind size is dialed in correctly the pressure will rise to 9 bars of pressure almost immediately and stay there until the end of the extraction. With a pressure profile machine, the machine can be configured to apply pressure in a bell shaped profile, where the pressure might start at 2 bars of pressure for 6 seconds to preinfuse, then jump up to 7 bars for a few seconds, then 9, then 11, and back down to 8 and again back down to 6 before the extraction is completed. This varied pressure replicates the type of extraction you would get with a lever machine, but with a lever machine it's harder to get the exact same profile again and you can't vary the pressure in a controlled manner like you can with a machine with computer controlled pressure profiling.