The invention relates to a system for preparing beverage, including a second and first exchangeable capsule and an apparatus including a first brew chamber part having a cavity for holding one of the first and second capsules, and a second brew chamber part for closing the first brew chamber part and having an extraction plate for abutting against an exit face of the hold capsule, and including a central and a peripheral portion, the central portion being axially movable relative to the peripheral portion from a first position to a second position, the apparatus including a locking mechanism for locking the central portion in the first position when the cavity holds the first capsule. The invention also relates to an apparatus, a method and a capsule.