In combination a spouted pouch adapted to be filled with a flowable product by a filling machine, a plug, and a cap, wherein said combination includes a spouted pouch comprising: - a flexible material pouch body, - a spout having a molded spout body of plastic material, said spout body having at a lower end thereof an attachment portion that is attached to the pouch body, wherein said spout body has at an upper end thereof a tubular neck, which neck has an interior surface delimiting at least a section of a product passage that extends from a lower product passage opening through the spout body to a mouth opening at a top end of the neck, said neck also having an exterior surface, characterized in that said combination further includes an interference-fit plug, wherein the plug is releasably mounted over the top end of the neck of the spout body in an interference fit and hermetically seals the product passage of the spout body, which plug has a molded plug body of plastic material, wherein the plug body has a top portion and a downward depending outer annular wall adapted to be fitted over a top section of the tubular neck of the spout, wherein the outer annular wall has an interior surface which forms an annular sealing surface, e.g. an inwardly protruding seal bead, and wherein the exterior surface of the top section of the neck embodies a cooperating annular sealing surface such that a hermetic seal is present between the outer annular wall of the plug and the neck of the spout body, wherein the exterior of the neck of the spout body, below the top section thereof, is provided with an integrally molded first cap connector formation, wherein the plug is adapted to be removed by the filling machine and to be replaced by pressing the plug onto the neck after filling of the pouch with the flowable product, wherein said plug removal, filling, and replacing of the plug are preferably performed in an aseptic environment, wherein said combination further includes a manually openable cap that is adapted to be assembled on the spouted pouch after the filling of the pouch and the replacing of the plug onto the neck, said assembly preferably being performed by a capping machine in a non-aseptic environment, wherein the cap has a cap body that is injection molded of thermoplastic material, which cap body includes an annular skirt having an interior surface, an exterior surface, and a lower end, wherein a section of the interior of the skirt is provided with an integrally molded second cap connector formation that is adapted to cooperate with the first cap connector formation on the neck of the spout body, and wherein the cap body and the plug body are provided with cooperating snap-fit formations (78,58), wherein the cap body and the plug body are embodied such that, with the plug replaced over the top end of the neck, the cap body can be lowered over the plug in an manner causing the first and second cap connector formations (28,76) to cooperate and causing the snap-fit formations (78,58) to engage and thereby couple the plug to the cap, wherein the cooperating snap fit formations (78,58) coupling the plug to the cap are such that upon manually opening of the cap the plug remains coupled to the cap and is entrained with the cap so as to open the product passage and allowing dispensing of the flowable product from the filled pouch, and wherein the cap, below the skirt, is provided with an integrally molded tamper-evident structure that allows to visually evidence the first time opening of the filled pouch, and wherein the spout body, below the first cap connector formation, is provided with one or more integrally molded tamper-evident formations (33,34) that cooperate with said tamper-evident structure of the cap, such that upon first time opening of the filled pouch the tamper-evident structure evidences said first time opening. - a flexible material pouch body, - a spout having a molded spout body of plastic material, said spout body having at a lower end thereof an attachment portion that is attached to the pouch body, wherein said spout body has at an upper end thereof a tubular neck, wherein the plug is releasably mounted over the top end of the neck of the spout body in an interference fit and hermetically seals the product passage of the spout body, which plug has a molded plug body of plastic material, wherein the plug body has a top portion and a downward depending outer annular wall adapted to be fitted over a top section of the tubular neck of the spout, wherein the outer annular wall has an interior surface which forms an annular sealing surface, e.g. an inwardly protruding seal bead, and wherein the exterior surface of the top section of the neck embodies a cooperating annular sealing surface such that a hermetic seal is present between the outer annular wall of the plug and the neck of the spout body,