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 home 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.
Freezing Coffee Beans
Coffee ages slower if you cool it down. 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.
Dropping the temperature by 10 degrees slows down the aging process by a factor of 2
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.
The exception to this rule can be speciality beans. Freezing these can cause the bean structure to change, altering the taste when it is made into coffee. Try to check with the maker and see whether freezing is appropriate first.
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.
It is particularly important to use really fresh coffee with espresso as you get more aromatic intensity this way
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.
This means that too much air will not get into the containers which aren’t being opened. A dedicated container will only allow C02 to escape, not enter.