Fuente: WIPO "tomato" An opening device for a package comprises a collar having a central axis and delimiting a flow channel extending between an inlet opening of the collar configured to allow entry of the pourable product into the flow channel and a pouring outlet of the collar configured to allow exit of the pourable product from the flow channel and a cutter configured to break the separation membrane and being at least partially arranged within the flow channel. The opening device further comprises a retaining device configured to block movement of the cutter out of the flow channel and through the pouring outlet by inducing a rotation of the cutter about a rotation axis transversal to the central axis. The retaining device comprises a retaining element and an interaction element configured to interact with one another so as to induce the rotation of the cutter about the rotation axis.