A dispensing system for use on a liquid container such as a bottle or the like for dispensing the liquid contents from the bottle. The outlet opening of the container is closed by the improved throat plug assembly of this invention having a valve positioned therein which is open when the container is mounted in a dispensing fixture which is closed when the container is not mounted on the dispensing system. A plastic spring yieldably urges the valve to its closed position. In the preferred embodiment, a retainer and plastic spring are of one-piece molded construction. The throat plug assembly also includes a specifically shaped valve which is opened slightly when the container is being stored or transported to vent vapor pressure from within the container should the same be necessary.