Improved fitment assemblies for headspace gas removal. In one configuration, a fitment assembly includes a fitment defining a fluid pathway between an interior and an exterior of a container, the fitment including a tubular body having an upper neck portion and a lower neck portion, the lower neck portion depending from the upper neck, the upper neck portion including a proximal end defining a proximal opening. The lower neck portion including a distal end defining a distal opening, the tubular body defining a central bore that passes therethrough, the central bore being concentric about a central axis and passing through the proximal opening and the distal opening a flange for coupling with a container, the flange extending radially outward at a junction with the upper neck portion and the lower neck portion, wherein the lower neck portion is configured to extend into the interior of the container.