While the raw coffee can be stored for years without significant deterioration in the quality, roasted coffee beans only for several weeks while the grounded coffee loses its aroma within minutes. Unless we roast the coffee ourselves, the long shelf life of raw coffee means no benefit to us, but we all must solve the storage of the roasted coffee.
We must consider many factors during storage. During the roasting process -and the following days-, carbon dioxide is released from the coffee grains continuously. The factories; therefore; use a kind of airtight packaging, whose one-way valve allows the getaway of the resulting carbon dioxide, but which does not let in the external gasses and oxygen. All the premium coffees are packed with this technology, but this method is rarely used in the lower price range. Since carbon dioxide is generated in any case, the factories can only leave the grounded coffee to rest deliberately before packaging. Thus, all carbon dioxide will leave until the closure of the packages. Obviously, this is not the best way to preserve the aroma of coffee, therefore we are better off if we avoid these types of coffees.
But we have to open the bag anyway, so we have to set up a strategy to minimalize the deterioration of the coffee’s quality until we consume it.
We have to stall off the oxygen from our coffee. We can buy a storage box, which lets us pump out the air through a valve. The kickback of this solution is the fact that vacuum even sucks out the carbon-dioxide from the inside of the coffee beans (these are important for the aromas). We may also use folding glasses, but the oxygen that closes in together with the coffee still exerts its effects.
Whatever method we use, we always have to open the bin before brewing. So probably the best solution is to divide the coffee into smaller doses (10-15 decagrams) after unfolding the original package and to keep them in separately. Thus we only have to unfold smaller doses at once.
We may use the original bag for storage or better quality plastic bags as well. In both cases, we should tamp the remaining air out of the bag. We may wriggle the well-sealed bag delivered from air in plastic wraps in three or four layers or if there is a vacuum container, the coffee can be stored in a slight vacuum or can be placed in buckled glass. Some preserve coffee with freezing, but this may neither be a good solution. If you choose this method anyway, you should consider that you can only freeze coffee one time. Here, too, we should hermetically package the coffee in the original or another plastic bag, squeeze out as much air as possible and at the end wrap it again in a second layer, so it will not take over the smell of other foods. We should take the coffee out before use, it needs half a day to defrost. You can store the whole coffee for two to three months, but this won’t work with ground coffee.
We should note another thing about the shelf life of coffee. If the grounded coffee loses its flavor, only the pleasure of drinking coffee will be smaller, our health will not be damaged. However, there is one thing you absolutely must avoid: the storage of brewed coffee for a longer period of time. Most people drink coffee while it is hot, but some might favor cold espresso. According to the current state of science, extremely harmful chemical processes start up in brewed and abandoned coffee, and its consumption may be as carcinogenic as the consumption of heavily burnt foods.