This is the big question we ask ourselves when we learn that coffee oxidizes very quickly and loses all its properties in a short period of time. They tell you, "Did you know that if you leave freshly ground coffee exposed to the air in just 40 minutes, it loses 80% of its flavor and aroma?" And you immediately think, "Wow, how can I store the coffee once I open it so it stays fresh longer?!"
To understand this, let's first explain what happens after coffee is roasted and how it evolves, so we can better preserve it. Even after roasting, coffee continues to undergo chemical changes . All the aromas and nuances it develops during roasting evaporate over time, especially due to contact with oxygen. This process causes the coffee to lose these aromas and flavors, making it increasingly stale and bland. If we were to leave some coffee beans exposed to air, we would notice these stale notes and other properties dissipating. A month after roasting, the coffee would be practically unrecognizable compared to when we first bought it.
There are many tips and myths about how to best store coffee, but sometimes these tips do more harm than good. The most common mistake is storing it in the refrigerator in a non-airtight container. The simple act of opening and closing the refrigerator to get other food causes the air inside the coffee container to condense and create humidity, another major enemy of coffee. This achieves the opposite of what we're trying to do: preserve the coffee.
Humidity, oxygen, and heat are the three elements that most significantly cause coffee to lose its properties. Therefore, to preserve coffee as best as possible, we must try to minimize exposure to these factors. When we receive our freshly roasted coffee, we should keep it in its original packaging, unopened, until we're ready to use it. Yes, we know it's very tempting to open the freshly roasted coffee as soon as you receive it to enjoy that wonderful aroma that the best specialty coffees give off, but you must resist the temptation! Of course, this is only true unless you have a vacuum-sealed jar to transfer the coffee to, removing all the oxygen and thus avoiding one of the factors that will spoil it. And that's right, one of the best systems for preserving coffee is, once we open the primary packaging, or the one that comes from the house, to put it in a vacuum jar so that we can take out the one we are going to use each time, and when we already have our daily ration of coffee, we can vacuum it again so that our coffee is in contact with oxygen for the shortest possible time.
We absolutely do not recommend putting it in the refrigerator, for the reasons mentioned before. Even if it's vacuum-sealed or in its original packaging, the regular use of the refrigerator—opening and closing it repeatedly—will cause some moisture to condense inside the jar or can, and this is a death sentence for our coffee. In two days, it will be rancid and will have lost all its freshness. Therefore, we recommend storing it in the pantry or cupboard where you keep other foods, always trying to keep it as far away as possible from any heat source.
We've conducted studies where we vacuum-sealed coffee samples in home vacuum-sealing bags, and after a year and a half in the freezer, the coffee retained its freshness and initial flavor. For this type of preservation, it's crucial to control the humidity inside the bag. If the vacuum isn't completely sealed, or if the bag has any small openings, moisture will build up, just like in the refrigerator, and spoil the coffee.
We already know that the best way to store coffee is in an airtight jar in the pantry. Each time we take out the coffee we're going to use, we simply re-air the jar, and this way the coffee can last perfectly well for several months. Another thing to keep in mind is that coffee is constantly releasing gases and aromas. So, if we leave the jar in the airtight jar for several days without opening it, the vacuum pressure will be lost. This isn't because the jar is broken or that we forgot to air it; it's simply that the gas released by the coffee has equalized the pressure with the outside of the jar. Since there's no oxygen inside (because it's all gas released by the coffee), it continues to do its job of preserving the coffee properly.
