As coffee rests after roasting, it releases CO2. This process is called “out gassing”. This generally prevents staling, or oxidation, for the first few days of a roast. Dark roasts will out gas longer than medium or light roasts, and hence they can benefit from a longer resting period. Generally coffee is best rested for 24 hours before brewing. Once cool, roasted coffee is best stored in an air tight container or container with a one-way valve designed to release CO2. Roasted coffee can be double wrapped and placed in a freezer and left there to prolong its freshness. Once you are using the coffee, it is best to leave it out at room temperature and not store it in the freezer as the temperature changes are not good for the coffee.