Abstract: A method for atmosphere modification in a container during the sealing process that includes deploying a closure head on the container so as to enclose at least the container-opening and create an air-tight seal such that an interior volume of the closure head is isolated from the ambient atmosphere. The closure head having at least one conduit providing fluid communication between the interior volume and at least one of a vacuum source and a pressure source. The method also includes creating at least a partial vacuum inside the container, inserting a replacement atmosphere into the container by means of the pressure source, sealing the container, and removing the closure head from the container. Devices for implementing this method are also disclosed.