Abstract: A cap assembly for a container that holds a perishable product. The cap assembly defines an opening through which the perishable product inside the container can be accessed. At least one obstruction plate is present within the cap assembly. Each obstruction plate is positionable between an open position, where the obstruction plate is clear of the opening, and a closed position where the obstruction plate obstructs the opening. A mechanism is provided within the cap assembly that automatically moves each obstruction plate from its open position to its closed position when the shelf life of the perishable product has expired. Optionally, the cap assembly may also include at least one condition sensor for detecting a condition harmful to the perishable product in the container. The mechanism also closes each obstruction plate if such a harmful condition is detected by the condition sensor.