When specialty coffee came to prominence in the 90’s, roasters came up with this idea that coffee should be consumed within 2 weeks after being roasted in order to enjoy the flavors of coffee at its fullest. This idea was likely developed from quality graders who have highly developed taste palettes and can really taste a decline in flavor intensity after a few weeks. While I don’t dispute a coffee grader’s abilities, as a roaster I can tell you that such degradation of flavor is so miniscule that most roasters can barely tell a difference, which means the greater percentage of coffee drinkers really won’t be able to taste a difference. So why did this idea that coffee is only good for a couple of weeks take off in the specialty coffee industry? One can speculate that it’s likely a gimmick in order to get people to purchase coffee more frequently and therefore help coffee companies make more money, but again it is simply a speculation and we won’t ever really know.
So does coffee have an expiration date, and does it ever really go “bad”? Well, the short answer is yes, but the shelf life of coffee can be extremely long before it really starts to “rot”, and even then there would have to be sufficient moisture in the coffee for it to really become spoiled. Truth is roasted coffee is an extremely dry product, kind of like rice and whole grains, so this prevents it from spoiling for at least a year from when it was roasted. However, after several weeks the coffee becomes stale in flavor, but the amount of time it takes for it to become stale is considerably longer than 2 weeks, and it also depends on different factors.
Before diving into what factors affect coffee’s flavor longevity, let me briefly explain the process of “degassing” of coffee. Right after being roasted, coffee beans contain a lot of CO2 (carbon dioxide) as a byproduct of roasting, and as the coffee sits the CO2 slowly escapes. After about 2 weeks of roasting, coffee has almost completely degassed and the flavors present in the beans are the only thing you really taste. It is also at the 2 week mark that most roasted coffees begin to lose their flavor, but they do so at a very gradual pace. CO2 is also a natural flavor preservative, which is why the flavor of coffee degrades at a very gradual rate.
Now that we know about CO2 and coffee, I will talk about a few factors that determine how rapidly a coffee will degas and ergo affect how quickly it loses flavor. These factors are the roast level of the coffee, how it is stored, and whether the coffee is whole bean or ground before packaging. As a general rule, the darker the coffee is the shorter its shelf life in terms of flavor. This is because the darker the coffee is, the more porous the beans become and the more rapidly CO2 can escape. This means that lighter coffees will generally retain their flavor for longer than dark roasted coffees. Also, roasted whole bean coffee will retain its flavor much longer than pre-ground coffee, and this is because coffee degases extremely fast right after it is ground. Pre-ground coffee will lose its flavor as quickly as a week, and after that stale flavors really begin to develop, which is why it is recommended to purchase whole bean coffee if freshness is a top concern. Next we will look into an experiment KLLR did in regards to coffee flavor longevity and coffee bean storage.
In March 2024, KLLR Coffee did an experiment with coffee storage and flavor longevity. We used our Espresso Blend for the experiment. On March 20, I roasted a batch of our Espresso Blend, and from that same batch I took 5 small samples and put them in 4-ounce mason jars that have a screw-on lid and not air-tight; we also bagged 12oz in the valved sealed bags that we use for all of our coffees and set that aside to try 3 weeks after roasting. We tried the small samples of coffee at 5 different times:
- 4 hours after roasting.
- 24 hours after roasting.
- 1 week after roasting.
- 2 weeks after roasting.
- 3 weeks after roasting; at this point we also tried the bagged coffee.
We prepared all samples using 21 grams of coffee and 340 grams of water at a temperature of 202°F on a Curtis Gold Cup brewer. Here are our findings:
- 4 hours post roast: the coffee was caramely, a little citrusy and very chocolatey with a prominent carbonation taste, similar to carbonated water.
- 24 hours post roast: the coffee was floral, citrusy, chocolatey, and a little less caramely; at this point, the taste of carbonation was almost completely gone.
- 1 week post roast: the coffee was chocolatey, it had notes of sweet citrus, caramel, black tea, and brown sugar; there were no flavors of carbonation at this point.
- 2 weeks post roast: the coffee’s chocolate notes became much sweeter, the black tea notes were prominent, and it had a very pleasant flavor of sweet lemon.
- 3 weeks post roast: at this point we tried both the coffee from the little jars and the coffee from the bag. The coffee from the jar still had plenty of flavor notes, but there were some very small but definite signs of staling. Much to our pleasant surprise, the coffee from the valved bag tasted almost 100% like the coffee that had been in its jar for just 1 week!
Based on our experiment, we learned that coffee retains its flavor much longer when it is kept sealed in a valved bag, and coffees stored in non-airtight containers will lose their flavors at a considerably faster rate. Also, based on the same experiment, we recommend storing coffee in an airtight container after its bag has been opened in order to retain freshness as long as possible. A great container that we recommend is the Fellow Atmos Vacuum Canister; back in April, I stored 1lb of two-week-old “1907” in my personal Fellow Atmos Vacuum Canister, and I kept it there for another two months; much to my very pleasant surprise, by the end of it it still tasted pretty fresh! In comparison, around the same time I had an opened 12oz bag of “The Americas” (currently Cauca, Colombia), and by the time it was two months old it still tasted pretty fresh!
Of course there are other factors that can affect how quickly a coffee “goes bad”, factors like farm elevation, coffee bean density, and quality of the coffee bean, but that might be a different blog post altogether. For now, I hope you learned something new regarding coffee and flavor retention, and I hope this eases your fear of your coffee going stale after only 2 weeks of opening!