Why Freshness Matters: Aroma and Taste
In our last entry we covered how to tell whether coffee is safe for use past a certain time. The expiration date is, in some ways, only a suggestion. We've already seen how it can be safe to drink coffee that's past its prime. Because it's safe, however, doesn't mean that it's going to have the same great taste that it had when it was fresh. When it comes to how your coffee smells and tastes, the expiration date isn't the date that matters.
Aroma If you've ever tried to eat something unpleasant (versus say, sneaking it to the dog), you may have held your nose to limit the unpleasant taste. You've probably also noticed that even your favorite things don't taste quite as good if your allergies are acting up, or if you've got a cold. The reason for this is that your sense of smell is vital to your sense of taste. The aroma of coffee degrades quickly, meaning that its taste is going to be much less nuanced as it ages than it was when it was fresh.
Taste Keeping coffee over the long term is similar to storing spices for long periods of time. Even if it hasn't gone bad, its taste isn't all that it should be. If you've had a jar of garlic powder sitting in your pantry for an extended period of time, you'll notice that it doesn't smell or taste as strong as it did when you first bought it. It still tastes more or less like garlic, but it's missing something; you might be tempted to use more to kick up the flavor, but the problem is that you're getting more of the same flat taste, just in higher volume. You can't get back the compounds that have been lost to age. Coffee is the same way. You won't recover what's lost; you'll simply have more of what's left. Your coffee will be flatter and less dimensional than it would have been if you used it when it was still fresh.
Whole Beans or Ground? Not everyone has the money, time, or inclination to invest in a top-of-the-line burr grinder. Coffee that's pre-ground has its share of advantages. It's convenient, it can be less expensive, and you don't have to second-guess whether you've got the right grind for your brew method of choice. There's a problem with ground coffee, however. A whole coffee bean retains more flavor longer; once it's been ground, the clock is ticking. Ideally, you should brew within a half hour of grinding coffee to ensure maximum flavor. Think about that the next time you purchase coffee at the grocery store that may have been sitting on the store's shelves for weeks, and may have been sitting in a warehouse for some time before that.
Keep Coffee in the Fridge or Freezer? The short answer is, "Neither, if you can help it." Freezer burn isn't just for meat and veggies. Storing coffee in the freezer is a lousy idea because even though it retards spoilage, freezing coffee helps to draw out some of the grounds' natural moisture and flavor. The beans may not have spoiled, but they're not going to taste as good as they would have if you'd bought fresh, ground right before brewing, and if you drink the coffee as soon as it's brewed. Freezing leaves coffee that doesn't smell, or taste, like much of anything. It's also worth noting that the beans are porous, allowing them to pick up the tastes and odors of whatever they're stored with. Unless you're particularly fond of Arabica Arabiatta, the refrigerator or freezer is not the right place for whole or ground coffee.
The Best Way To Store Coffee If you have to store coffee, the best way to do it is by storing whole-bean coffee. Whether you're buying whole-bean or pre-ground coffee, however, you'll want to keep it short-term in an airtight, opaque container that's kept in a cool, dry place. Large quantities of coffee might seem like a bargain, but quite a bit depends on how quickly you'll consume it. You're better off, especially if you're only brewing a cup or two at a time, buying smaller containers more often versus buying an enormous container that will sit for weeks on the shelf, since the quality of the coffee brewed will decline markedly in a relatively short time.
In Conclusion Whether you're a "serious" coffee drinker or decidedly more casual about it, freshness matters. That's true whether you're paying $20.00 per pound for the good stuff, or a can of Maxwell House that you picked up because you happened to have a coupon. Either way, they're your taste buds, and it's your money. With that in mind, remember that freshness -- and the lovely coffee aroma and taste it brings with it -- means better coffee and less money wasted.
Further Reading: coffeeresearch.org: Coffee Chemistry: Coffee Aroma Black Bear Micro Roastery: A Question of Freshness A TED talk by Asher Yaron: What You Didn't Know About Coffee