A gas release container comprises a container body having a bottom wall and a side wall extending upwardly from the bottom wall and terminating at an upper edge, a removable closure affixed to the upper edge in a substantially gas-tight manner, and a gas release valve in a wall of the container body and operable to release gas from the container when the pressure differential between the interior and the exterior of the container is sufficient to open the valve. The removable closure can include a flexible gas-barrier membrane sealed to the upper edge of the container body. A lower surface of the membrane and the upper edge of the side wall comprise heat-sealable polymer materials, and the membrane is heat-sealed to the upper edge, preferably by induction sealing. The closure can include an overcap.