Capsule for the preparation of a food product in a food preparation machine at high pressure

1. A capsule for delivering a food product by injecting a fluid under pressure into the capsule when the capsule is inserted into a receptacle of a food preparation machine, the capsule comprising a chamber defined by capsule side walls, a flexible bottom wall, the chamber containing at least one ingredient to be dissolved and/or extracted by the injection fluid, and a beverage dispensing structure comprising at least one dispensing opening located through the bottom wall, the beverage dispensing structure also comprises a pressure retaining element adapted to retain a certain predetermined dissolution and/or extraction pressure in the chamber for the mixing of the injection fluid with the ingredient and located in the vicinity of the bottom wall, outside of the chamber, the pressure retaining element comprising at least one protrusion located in correspondence to the at least one dispensing opening so that the protrusion is located in the corresponding opening and restricts its section, at least at the time injection fluid inside the capsule chamber presses onto the flexible bottom wall and moves the flexible bottom wall towards the pressure retaining element.

2. The capsule of claim 1 , wherein the pressure retaining element is an integral extension of the capsule bottom wall.

3. The capsule of claim 1 , wherein at least one protrusion of the pressure retaining element has a radial cross-sectional shape that differs from the shape of the opening to which it corresponds.

4. The capsule of claim 1 , wherein at least one protrusion has a general longitudinal profile such that its radial cross section generally increases from apex to base.

5. The capsule of claim 4 , wherein the protrusion has a general shape selected from the group consisting of: a hemisphere, a truncated hemisphere, an elliptical paraboloid, a thorn-like cone, a polyhedron, a truncated tetrahedron, a cone, a truncated cone, a pyramid, a truncated pyramid, and combinations thereof.

6. The capsule of claim 4 , wherein the pressure retaining element comprises at least one cushion located in the vicinity of the at least one protrusion, the cushion having a height smaller than, or equal to, the protrusion, for maintaining the capsule bottom wall at a distance from the protrusion base if the bottom wall is moved due to fluid pressure inside the capsule, such that the diameter of the opening is greater than the radial cross-section of the protrusion to which it corresponds.

7. The capsule of claim 1 , wherein the at least one opening is pre-pierced in the capsule bottom wall at the time the capsule is placed in the machine for use.

8. The capsule of claim 1 , wherein the at least one opening is created through the capsule bottom wall by at least one effect selected from the group consisting of:

a local dissolution of the capsule bottom wall material upon effect of temperature of the injection fluid when the fluid contacts the internal surface of the bottom wall, and/or upon chemical reaction between the bottom wall material and the injection fluid;

effect of the fluid pressure inside the capsule chamber onto a predetermined area of the bottom wall, which is pre-pierced but in a closed position and opens after local deformation of the bottom wall, or which is a weakened area of the bottom wall; and

effect of a mechanical member located outside of the capsule, onto the capsule bottom wall.