Should You Be Storing Coffee in a Coffee Canister?
Most bags of coffee have enough beans to make about 16 cups. Of course, this depends on how you brew your coffee. But, roughly speaking, if you drink a cup of coffee a day, a typical bag will last about two to three weeks—that’s approximately how long most roasters would estimate a bag of coffee stays fresh.
Not everyone finishes a bag of coffee within that time frame, and you might have noticed the brew from the last batch of beans tastes significantly different than the first. When roasted coffee begins to stale, all of its the lovely components—the aromatics, sweetness, and acidity—start to fade. Over time, your coffee might begin to taste flat, even rancid. So what’s an occasional coffee sipper to do as they slowly work through their bag of beans? What about the coffee aficionado who buys multiple bags of beans, toggling through their selection but ultimately slowing down how quickly they go through their stash?
One possible solution is to store your coffee in a coffee canister: some sort of container whose expressed purpose is to keep coffee fresher, longer. But do you really need one? Or is storing it in its bag just as good? We tested out three different types of canisters to figure it out.
What Is Fresh Coffee, Anyways?
Freshness in coffee is a weird thing. For one, it’s not quantifiable—there’s no real expiration date, although some bags do have somewhat meaningless dates that are one to two years after roasting (and some roasters are experimenting with “best by” dates). And regardless, coffee doesn’t go bad in a way that can make you sick. If you drink a very old bag of coffee, the worst it can do is taste…not great. Also, freshness can’t be visually assessed just by looking at the beans, and there’s no one flavor or giveaway sign that a coffee's stale.
I talked a little bit about freshness in my breakdown of coffee blooming and bubbles. Coffee is an agricultural product—basically, think of it like any other food item we grow and eat—and like most foods, oxygen is what causes coffee to stale. Roasting creates carbon dioxide (CO2) inside of coffee beans, and, in a way, CO2 acts almost as a shield around coffee, protecting it from oxygen. But CO2 eventually leaves coffee beans in a process called degassing, so coffee begins to lose that protective layer over time.
However, unlike most food items, freshness does not have a linear relationship with flavor and quality: in fact, most roasters would recommend letting your coffee rest for at least a few days after roasting, and our understanding of resting and peak freshness has morphed over time. I remember when I first started as a barista and thought anything five to seven days off-roast was old, and now I barely bat an eye at a coffee that’s been resting for two-plus weeks. CO2 acts as a shield against coffee going stale—but it also acts as an inhibitor to extracting flavor from your grounds. Some folks even recommend waiting as long as eight weeks to enjoy a bag of beans, depending on the roast profile—lighter roasted coffees will release CO2 slower than darker roasted beans because their cellular structures aren’t as open (so CO2 has a harder time moving through the inside of a coffee bean, even though less CO2 is created with lighter coffees).
And, just to complicate things more, it’s important to note that “resting” a coffee usually means storing it in a container with a one-way valve (the valve lets CO2 out as the coffee degasses but doesn’t let oxygen in)—not simply that a bag of beans will stay tasty for that long. Every time you open a bag of beans and jostle it around, you’re displacing CO2 and letting oxygen in. Some coffee roasters even go as far to recommend only scooping beans out from the very top layer of your bag so as not to disturb the coffee below. Freshness is such a complicated topic in coffee that scientists are studying how it works to understand better what’s going on as coffee stales.
Are Coffee Canisters Necessary?
If you were to ask me 10 years ago if coffee canisters were a necessary coffee tool, I would have said yes. I remember a time where leading coffee brands used what essentially amounted to a fancy version of a brown paper bag for their packaging, closing the tops with a tin tie—which did nothing to preserve freshness.
But now? Almost all coffee bags have two really key features to preserve freshness: one, they almost all have a one-way valve, which I mentioned earlier. One-way valves make sure that the CO2 from your degassing coffee has somewhere to go. But secondly: most coffee bags have zip top seals, making them an effective displacement container, especially if you take the added step of squeezing the excess oxygen when you seal the bag. Some coffee companies go an extra step, doing things like nitrogen flushing the bag to displace oxygen when being sealed.
In this test, I used the bag my coffee came in not just as a control, but also as a viable coffee canister in its own right. I wanted to see if the zip top closure and the one-way valve did enough to keep coffee fresh.
Types of Coffee Canisters
Although most coffee canisters claim to do the same thing—keep coffee fresh—not all canisters are made the same. Coffee YouTuber James Hoffmann tested out a range of coffee canisters on his channel, and he sorted them based on three categories:
- Airtight Containers: An airtight container is pretty self-explanatory: it keeps air out. Almost anything with a twist-off lid (think Mason jars) will keep air out of a container, and can also be handy for keeping out other contaminants like dust or bugs.
- Displacement Containers: These types of containers involve some sort of mechanism to displace air out of a container. One way to visualize how these kinds of containers work is by pushing out the oxygen of a zip top bag.
- Vacuum-Sealed Containers: Vacuum-sealed containers pump oxygen out of containers to create—you guessed it—a vacuum within the container. The vacuum produces a pressurized seal that prevents oxygen from coming in.
Hoffmann’s video tests about a dozen coffee canisters, and he picks one canister in each category that he thinks performed well, although he notes at the end of testing that he didn’t see a huge difference in flavor between the styles of canisters.
I wanted to really hone in on that observation. I can speak on and on about freshness and its complexity, but in a real life scenario where I’m just brewing coffee at home, would I be able to tell the difference, taste-wise, between each style of canister? I chose the three canisters Hoffmann singled out—the Coffeevac, the Airscape, and the Fellow Atmos—each representing a category of canister styles, to put his final conclusion to the test.
I ordered a coffee roasted by my friends at Lost Sock Roasters in Washington, D.C., and I specifically picked a darker-roasted coffee to speed up the oxidation process. My coffee was roasted on October 19th, I opened it on October 26th, and divided out four equal doses of coffee amongst the three containers and the bag that the coffee came in (which featured a zip top and one-way valve). I then left the canisters alone for eight days, and then brewed coffee with beans from each container using a Kalita Wave and a brewing recipe of 30 grams of coffee to 500 grams of water.
Each canister worked a little differently:
- The Coffeevac simply had a button you pressed to put on and take off the lid.
- The Airscape has both a lid and a plunger with a handle you use to press the air out.
- The Atmos has the most innovative design feature—unlike most vacuum-sealed canisters, which usually have a detached piston you have to use to pressurize the container, the Atmos dispels oxygen by twisting the lid back and forth rapidly. After about 30 seconds, a small green dot will show up on the lid to indicate the canister is pressurized (you have to check in on the canister every five days or so and repressurize).
I decided that I wanted to primarily rely on taste assessments here because I saw a disconnect between how we talk about freshness and the actual implications freshness has on the way folks at home were consuming coffee. Sure, a coffee that’s been open for a month might not be super fresh, but if it still tastes good, that shouldn’t matter. Likewise, I saw folks recommending super long resting times, but that felt impractical for most home consumers. How many people are buying bags of coffee to let sit on their shelves for weeks before opening?
However, I did want to see if the canisters would effect brewing times: in general, coffee goes through sort of a bell curve in terms of how quickly it brews. Samo Smrke, a scientific associate at the Zurich University of Applied Sciences, did an experiment with espresso extraction and found that “very fresh coffee was flowing fast. A coffee that aged a bit flows slower but then once it’s getting really old, it starts to flow again faster.” I wasn’t sure if this was replicable with drip brewing, nor did I duplicate Smrke’s brewing conditions (they used, as they described during their talk with the Specialty Coffee Association, “a fresh coffee, a two months old coffee, and a days old coffee.”) However, all the brewing times were within 20 seconds of one another:
I then tasted all four after letting each cup sit for five minutes, and then I randomized the cups and had fellow Serious Eats writer Jesse Raub taste them (I couldn’t provide anonymized results since I had to brew the cups one at a time, so I knew which cup was which based on temperature). I had him give me his impressions and compared them to my own.
In general, none of the coffees tasted that much different from one another, but both Jesse and I were able to group the coffees into two separate groups. We found that the Airscape and the Coffeevac cups were indistinguishable from one another, but flatter than the coffees from the Fellow and the coffee bag. We also found the coffee brewed from the Atmos and the coffee bag more vibrant, with the Atmos edging out the coffee bag just a bit—but not by much. I doubt I’d notice the difference if I wasn’t looking for it.
The Conclusion: Most Coffee Canisters Aren't Worth It (with the Exception of Vacuum-Sealed Ones)
This sort of feels…anticlimactic, right? I felt the same way Hoffmann feels at the end of his video. “The results, from a taste perspective, were not what I hoped them to be,” he says. I wanted there to be big, surprising results, but there weren’t, which leads me to the same conclusion Hoffmann makes: “That would also mean, in many situations, I would also be happy storing coffee in a resealable bag.”
So the first place to start when considering buying a coffee canister is how you buy coffee: if you order beans online or buy bags from your local coffee shop, the best piece of advice I can offer is to buy coffee from roasters who make resealable bags. Squeeze out any excess oxygen anytime you open the bag, and make sure to store your coffee in a cool, dark place (we didn’t talk much about this, but I specifically chose non-transparent canisters to test since light can affect aging and staling).
But if you buy your coffee in bulk or regularly share beans with others, an airtight container like a Mason jar will do well for you, unless you really want to step up your freshness game—then I’d skip over any airtight or displacement canisters and go straight for the Fellow Atmos. Not only did it keep coffee the freshest and the best-tasting of the bunch of canisters we tested, but its design features make it easier to use than similar models.
What other elements should I consider when storing coffee?
You want to keep your coffee away from light, heat, and moisture. In this experiment, we only purchased canisters that were opaque, although many manufacturers sell glass or clear canisters, which are fine as long as you store them in a dark place like a cabinet or drawer.
Can I store ground coffee in a canister?
In the airtight and displacement ones, yes, but not in the Fellow Atmos. According to the Fellow website, “Storing ground coffee or very fine substances may clog the intake valve and prevent a proper vacuum seal.”
Can I use a coffee canister for other items?
Yes! There’s nothing about most canisters that are specific to coffee—tea, spices, or anything that could degrade over time when exposed to oxygen. But be mindful and read the instructions to make sure you can use your canister for other things. For example, Fellow suggests you shouldn’t store ground coffee in their Atmos canisters since the particles could clog the intake valve.