A collapsible pouch closure assembly comprising: - a spout having a spout body that is injection moulded of plastic material, said spout body having a spout seal portion with an exterior surface, the spout seal portion being adapted to be sealed between peripheral edge zones of two foil walls of a collapsible pouch, and said spout body having, above said seal portion, a tubular neck, wherein a product passage extends through the spout seal portion and the neck of the spout, said neck forming a mouth at a top end of said product passage, said neck having an exterior side; - a rotational cap that is injection moulded of plastic material and that is secured on said neck of the spout in a closed position of the cap on said neck such that the cap seals the product passage, and the cap - for removal of the cap from the neck of the spout by a user to open the product passage - being adapted to be manually rotated from the closed position in an opening direction; wherein the cap comprises a top wall and a downward depending skirt, said skirt having an interior side, an exterior side, and a lower edge remote from the top wall, wherein the exterior side of the neck and the interior side of the skirt have cooperating rotational connection means, preferably first and second screw threads on said neck and skirt respectively, characterized in that the cap is provided with at least one integrally moulded anchoring portion that overlaps an area of the exterior surface of the spout seal portion (65a,b,c) and that is adapted to be sealed between the spout seal portion and a peripheral edge zone of one of the foil walls of the collapsible pouch, said cap including a frangible zone with one or more frangible bridges (102,103) connecting the anchoring portion to the skirt of the cap; such that upon rotating the cap in opening direction by the user from its closed position for the first time, the one or more frangible bridges break thereby evidencing the removal of the cap from the neck. - a spout having a spout body that is injection moulded of plastic material, said spout body having a spout seal portion with an exterior surface, the spout seal portion being adapted to be sealed between peripheral edge zones of two foil walls of a collapsible pouch, and said spout body having, above said seal portion, a tubular neck, wherein a product passage extends through the spout seal portion and the neck of the spout, said neck forming a mouth at a top end of said product passage, said neck having an exterior side; - a rotational cap that is injection moulded of plastic material and that is secured on said neck of the spout in a closed position of the cap on said neck such that the cap seals the product passage, and the cap - for removal of the cap from the neck of the spout by a user to open the product passage - being adapted to be manually rotated from the closed position in an opening direction; at least one integrally moulded anchoring portion that overlaps an area of the exterior surface of the spout seal portion (65a,b,c) and that is adapted to be sealed between the spout seal portion and a peripheral edge zone of one of the foil walls of the collapsible pouch, said cap including a frangible zone with one or more frangible bridges (102,103) connecting the anchoring portion to the skirt of the cap;