There’s a science to storing coffee, and the first thing it tells us is that no, it is not better to store your coffee in the fridge or freezer.
The first rules for coffee storage is finding a place which is cool, dry and dark. Apparently, someone’s idea of storing your beans or grounds in the refrigerator/freezer got around quick. It comes from the call to keep them fresh. The problem is, the temperature change involved with removing the coffee from one of those places into a more humid, warmer climate, even for a short period of time, can result in condensation that results in wet coffee that is much more likely to mildew or only goes bad. Additionally, the hygroscopic characteristic of coffee means that not only does it absorb moisture from the surrounding air, it also absorbs odors and flavors. If your fridge is like mine, you already know what a pain it can be when you leave one thing uncovered in there, and then everything else tastes like that one thing or that one thing tastes like everything else. My partner and I have frequently been known to take a bite of something from the fridge and then to sigh and say: “It tastes like the fridge.”
You don’t want coffee that tastes like the plans!
Keeping your beans or grounds cool mostly means keeping them around room temperature and in the coolest part of your kitchen/pantry area that is not the fridge/freezer. The main thing you want to pay attention to here is that you understand storing it too close to the oven or other sources of heat, like the sun, is not a bright idea. Heat is used in the drying process for coffee beans, and if you don’t keep your coffee away from heat, you’ll continue that physically altering process beyond the point where the coffee producers deemed it best to stop.
This is also why keeping your coffee away from air and light is also important. Exposure to oxygen accelerates the time it takes for coffee to go stale and light, like heat, makes coffee go bad as well. Heat, gas and light exposure continue the roasting process, which has created volatiles in the coffee, initiating a gas-loss process that leads to coffee becoming stale. “A group of studies has found that losses of a few specific volatile compounds are responsible for a majority of coffee aroma loss,” according to a literature review of coffee freshness studies produced by the Specialty Coffee Association. Additionally, oxidization (exposure to oxygen) has been found to degrade the lipids in coffee in a way that directly contributes to the sour flavor of coffee that’s gone wrong. Rancidity also results from and “is accelerated by moisture, oxygen, [and] temperature.”
It is impossible to completely prevent these processes when coffee has been roasted because the roasting process initiates them. The goal is to slow them as much as possible to maximize freshness until such time that you can partake of, and thoroughly enjoy your coffee.
There are specific types of containers that are best for maximizing coffee freshness because they minimize coffee’s exposure to these stifling elements. Most packaging for coffee is not optimal for preserving freshness as long as possible because it does not reseal entirely. Containers like those used in Folgers’ packaging, the tubs with the snap-on lids, are good options because that snap is a suitable seal against air. You also want to make sure your containers are opaque to prevent the coffee’s exposure to light, so a clear Tupperware-style container isn’t the best option. A metal tin with a lid that closes tightly can be a decent choice, you’ll want to be mindful of any rust occurring in the container that could affect the beans, and you’ll also want to be extra cautious about that type of container’s exposure to heat because of the conduction qualities of metal. Paper containers may also be a little too porous to actually optimize your coffee’s freshness.
You can also guarantee optimal freshness by buying smaller amounts of coffee at a time, or buying whole beans and grinding them fresh as you go. The grinding process accelerates the staling and deteriorating process in the coffee, so if you just grind as much as you need at a time, you’ll extend your coffee’s shelf life. Taking that further, if you’re truly dedicated, you could learn how to roast at home and invest in raw beans, giving you the opportunity to roast small batches as you need them and maximizing the freshness as a result. Remember that roasting initiates that deterioration process so if you only roast as you go you won’t have to worry so much about your coffee going bad.
All of that aside, it is not as if you cannot consume stale coffee, it won’t harm you, it’ll just mean that the flavor will be off and the caffeine content and overall taste will likely be weaker. You’ll probably want to avoid coffee that smells/tastes rancid and even though mildew/mold tends to be simple no one really enjoys that flavoring. That’s why, ultimately, you do want to make sure when storing your coffee, you are doing so consistently the best way possible so that you’re truly getting your money’s worth.
Companies like PBFY (pbfy.com) produce commercial packaging so that if you’re in the coffee manufacturing and distribution business, you can find packaging that is specifically designed for coffee and food freshness and preservation. Their stand up pouches, for example, come in revealing designs and preserve the physical quality of whole coffee beans in a way that adds an extra protection to the quality of the beans. The less damage of any kind your coffee incurs the better it will be for longer.