Sterilizing packaging units including packing a sterilization container by receiving a rigid body having a lower surface, an upper rim, and side walls between the lower surface and the upper rim, wherein the upper rim defines an opening to an interior space of the body, arranging one or more packaging units in the interior space of the body, covering and sealing the opening of the body with a lid, and engaging a valve body in fluid communication with the interior space of the body to move the valve body to an open position; exposing the interior space of the body and the packaging units to a sterilant until the packaging units are sterilized; subjecting the interior space of the body to a negative pressure differential; and engaging the valve body to move the valve body to a closed position that seals the interior space of the body.