Unit for the preparation of a foamy beverage from a capsule and an opening plunger

A unit for preparation of a foamy beverage from a soluble product, the unit comprising:

• a collecting device with a seat arranged to receive a disposable capsule containing the soluble product, with the capsule containing at least one inlet port for a diluting fluid introduced into the capsule, at least one outlet port for delivery of a beverage provided by thorough mixing of the soluble product and the diluting fluid, and a bottom wall;
• and
• a throttling arrangement provided by an engaging surface of a plunger that is operatively associated with the outlet port of the capsule;
• wherein the engaging surface of the plunger is positioned and arranged outside of the capsule before the diluting fluid enters into the capsule, with the throttling arrangement created as diluting fluid is urged to enter the capsule by expansion of the capsule bottom wall and by forcing the engaging surface of the plunger to snugly fit through the outlet port, thereby limiting the introduction of the plunger inside the capsule to the limited displacement of the bottom wall as a result of its deformation under pressure and wherein the plunger is connected to a control mechanism that withdraws the plunger after the pressure in the capsule has been maintained a sufficient time to enable the soluble product and the diluting fluid to properly mix together to form the beverage.