This is a question I am often asked. Once green coffee beans have been roasted they slowly start to lose the aroma and flavour characteristics that make drinking coffee so enjoyable. Therefore it is important to purchase and store your coffee in the best possible way so as to obtain the most favourable shelf life. Here are my tips:
Look for coffee that has the roast date stamped on the bag as opposed to a 'best by date'. The former has become the de facto standard for artisan roasters who sell high quality speciality coffee. Coffee is at it's very best from between 4 days and 2 weeks after roasting which is something that you cannot be certain of if buying from a supermarket shelf.
Buy smaller amounts often. You should only buy enough for a maximum of one or two weeks of consumption.
Buy a grinder. Buying coffee beans as opposed ground coffee will ensure that its fragrance and flavour will not be lost as quickly.
The key to storing coffee is to protect it from heat, light, moisture and oxygen.
Most roasters supply coffee in a bag with a one-way valve. The purpose of this valve is to allow CO2 to escape without letting air in, which would make the coffee go stale quicker. Once the bag is opened this valve has no purpose.
So as long as you store your coffee in a cool, dark cupboard in an airtight container you will optimise its shelf life.
If your coffee came in a resealable bag, which is fine for storage, then squeeze as much air out as possible before resealing and putting back in the cupboard.
Storing in a fridge is inadvisable as it is full of moisture and coffee will quickly absorb moisture and flavour taints from nearby foods.
Storing in a freezer is only advisable if you have bought more coffee than you will consume within 2 weeks. Seal the coffee into portion sized airtight containers and store for a maximum of 1-2 months. Do not put back in the freezer after opening or refreeze.
Buy coffee as close to the roasting date as possible.
Only buy enough coffee for 1-2 weeks consumption.
Store it in an airtight container in a cool, dry and dark cupboard.
Grind only enough for your brew.