Abstract: In one embodiment of an apparatus and process for packaging foodstuffs or other materials in a rigid container sealed by a flexible cover, a desired quantity of material to be packaged containing or together with some water or other liquid is placed in the container, the flexible cover is secured on the container so as to leave at least one unsealed opening, the container is heated and/or placed in a partial vacuum to bring the liquid above its boiling point to cause or permit vapor generated by the boiling liquid to expel other gases from the container through the unsealed opening, and the container is sealed while gas or vapor is still flowing out of the container through the unsealed opening.