The present invention relates to a capsule containing a substance for the preparation of a beverage that is designed to be extracted by injection of a fluid under pressure. The capsule comprises a closed chamber containing the substance with at least part of the closed chamber including a retaining part made of a flexible membrane. One or more raised elements that face the membrane are associated with and forming part of the capsule. These element(s) are used to open the capsule due to a buildup of pressure therein. This rise in pressure causes relative engagement of the raised element(s) with the membrane until the membrane ruptures or is torn to release the formed beverage from the chamber. As the liquid of the beverage does not come into contact with the machine, hygiene is improved and cross-contamination is reduced when preparing a beverage from the capsule.