The present invention relates to a flexible container containing a liquid product, wherein the flexible container (2) comprises a closure having an inner end and an outer end, the closure being fixed through the wall of the flexible container (2) such that the inner end of the closure lies within the flexible container (2) and is in contact with the liquid product, and the outer end of the closure lies outside of the flexible container, wherein the closure has an open position and a closed position, and wherein the outer end of the closure is connected to a self-sealing valve (30) which opens when the closure is in the open position and when pressure is applied to the liquid product within the flexible container, and which closes when the pressure is released. In another aspect the invention relates to a process of making a liquid-filled, flexible container.