The freshness of coffee plays an important role in how coffee tastes. Like food, the fresher the ingredients, the better the flavour. As freshly baked bread tastes better than bread a week old, so do freshly roasted coffee beans. The two processes which affect the length of time coffee stays fresh for are roasting and grinding.
In green bean form, coffee can stay fresh for up to 2 years. However, once it has been roasted, it only stays fresh for up to 2 weeks. This is why it is best to buy your beans in raw form and roast at home using a dedicated roaster.
If you buy them pre-roasted, you should purchase in small amounts – just as much as you would use in a 1-2 week period. Coffee beans should be stored in airtight containers in a dark, dry and cool location.
If you have to buy more than a two week supply of coffee beans, you should freeze part of this purchase. Freeze them in a waterproof and airtight container, and they can stay fresh for up to a month.
Frozen coffee beans must be allowed to thoroughly defrost, between 2-4 hours at room temperature, before they can be ground; and great care must be taken to ensure that no ice from the freezer comes into contact with the beans, as moisture will cause them to deteriorate.
Once the coffee has been ground, it should be used as soon as possible. Air is coffee’s worst enemy, and as a ground coffee bean has a much larger surface area than a whole coffee bean, it is more exposed to air and becomes stale quicker.
If you do not have a coffee grinder at home and buy your coffee pre-ground, then it is a good idea to divide your coffee supply into several smaller portions. Keep each part in an airtight container and take coffee from only one of these portions at a time, using up all the coffee grounds before moving on to the next one.