A system for selectively delivering different beverages having different
foam levels by injection of a fluid under pressure into a capsule that
contains a beverage-forming substance. The capsules include a chamber
containing the substance and a beverage dispensing structure adapted to
retain a certain extraction pressure in the chamber before allowing the
beverage to flow out of the capsule. The system is characterized in that
first and second capsules are provided for selective use in the system,
with the first capsule having a first beverage dispensing structure
configured and positioned therein to retain a first extraction pressure
in the capsule, prior to the complete delivery of the beverage, and the
second capsule having a second beverage dispensing structure configured
and positioned therein to retain a second extraction pressure in the
capsule, prior to the complete delivery of the beverage. The first
extraction pressure is higher than the second extraction pressure so that
a greater amount of foam is created upon delivery of the beverage from
the first capsule as compared to that created by the second capsule. This
allows a user of the system to select a cartridge that produces a
beverage with the desired foam content.