The Problem:
Even after coffee is roasted, the beans continue to release CO2 gasses, which if not properly vented can give the coffee a "gassey" aroma and flavor. Unvented coffee storage can actually build up pressure after filling with freshly roasted coffee, and the more coffee the container holds, the more pressure is generated. Sealed coffee storage bags & jars which are unvented, can blow open due to the pressures caused from the release of the gas. The more oxygen the coffee is exposed to, the faster it loses its aroma and freshness.