There is one particular question that I usually get after talking to someone about the importance of fresh coffee: “How should I store fresh coffee beans?”
As I said before, if you want the best taste possible, you must use fresh beans. If coffee beans are not stored properly, they will break down much quicker than the 2-3 week window that I suggested in the previous post. Therefore, it is necessary to store your coffee beans properly. I will begin by addressing the reason for the necessity of proper storage, and then offer helpful tips and advice for storing coffee.
Why Do Coffee Beans Need Proper Storage?
Although this is a complicated matter, I will do my best to summarize the issue. When coffee beans are roasted, carbon dioxide is infused into the beans. Carbon dioxide helps protect and enhance the flavors and aromas of coffee. Coffee beans, however, naturally degas, releasing carbon dioxide. But, degassing can be slowed down if coffee is stored properly. On top of this, though, the number one enemy of roasted coffee is in fact oxygen. The presence of oxygen leads to the process of oxidation, which negatively affects the aroma and flavor of coffee as well.
Another factor that must be considered is moisture. The presence of water leads to the process of hydrolysis. Although water is necessary for making a cup of coffee, moisture in the air will negatively affect the beans before they are ever ground or brewed. Therefore, the fact that coffee naturally absorbs water is both good and bad. Good, because it is necessary for that perfect cup of coffee. Bad, because it does this on its own.
Temperature is another factor that must be considered. This truly is a factor that is often forgotten, but it remains a fact that temperature affects the rate at which coffee stales. This happens chemically, in that higher temperatures increase the rate at which chemical reactions occur, and physically, in that temperature affects the rate at which the degassing process occurs.
A final factor that should be considered is light. Direct sunlight can cause roasted coffee beans to stale more quickly. Direct light both increases the internal temperature of coffee beans and increases the chemical activity on the outside of coffee beans.
(A very helpful, yet technical, article addressing this issue can be found here.)
How Should Coffee Be Stored?
Coffee beans, then, should be stored in a place that is considerate of carbon dioxide and oxygen, moisture, temperature, and light. With those things in mind there are multiple ways of storing coffee. Some people will argue for one method over the other, but many of them work just fine, especially if you are drinking them within a 2-3 week window after being roasted.
Personally, the method that I use is a glass jar with a lid. The glass jar is just large enough to hold one pound of coffee, and the lid has a rubber seal that acts as a sealant once the lid is screwed on tightly. I keep this jar either in our pantry or on the counter away from direct sunlight. The benefit of this method is that glass jars with lids are not very expensive. You can even use a left over salsa or mason jar. If you use a jar that had something in it prior to being used for coffee, make sure that the jar has completely aired out so that the flavor of your coffee is not affected by what was perviously in there. Since coffee absorbs what is around it, a helpful idea for completely removing old smells is to put old coffee beans, whole bean or ground (not wet, used grounds though), inside for a time so that it soaks up all the bad stuff.
Other appropriate methods: an airtight canisters made specifically for coffee, like this one by Planetary Design, as well as certain coffee bags that some coffee roasters use, like this one that is plastic, resealable, and has a CO2 valve (helpful for immediately packaging fresh roasted coffee, allowing for the degassing process to occur while in the bag without being too much affected by oxygen).
What about storing beans in the freezer or the refrigerator?
In my experience this is one of those questions that everyone has a different answer to. Personally, though, I never store coffee beans in the refrigerator, and I only store coffee beans in the freezer if I am going to have the beans for more than a month without using them. I try to stay away from ever freezing them, but sometimes you find that you have a bunch of coffee beans that you will never use before they go stale.
The truth about refrigerators is that, though the temperature is cool, they retain much moisture, and moisture is not good for coffee beans, as mentioned above. Using an airtight container inside the refrigerator can help with coffee absorbing the aromas and flavors found inside the refrigerator, but every time that the canister is removed and opened the temperature of the beans and the canister will have to adjust, causing quicker staling and possibly condensation inside the canister.
Freezers, on the other hand, are often what are more debated. Truthfully, this is something that each person is going to have to figure out on there own. Every time that I have stored coffee in the freezer, there has been a noticeable amount of flavor and aroma loss, but it seems better than just leaving it out at room temperature. If you do decide to freeze coffee, it is important to use an airtight bag or canister. Some people put them in ziplock bags with aluminum foil around the bag, which works as a barrier to other gases in the freezer. However you do so, it is important to let the entire bag or canister cool down to room temperature before grinding the beans–this helps keep condensation at bay. Also, freezing coffee beans more than once quickens the degradation process, bringing about quicker staling.