Coffee Storage: Lies, Damned Lies, and the Freezer Myth

   Okay, so I went on vacation. I wanted to post this; I really did. The opportunity just never arose to really polish this post up all shiny and throw in all my clever jokes, and let's be honest: you wouldn't be reading this blog if it wasn't mildly amusing. I'm just a clown to you people. You sicken me!
   Anyway my loyal fans, each of whom I care about deeply, this week I'm going to discuss an oft overlooked and under-appreciated aspect of coffee preparation: storage. You may say to me, "John Jon, seriously? We all know how to store coffee.", and then you would expound upon the proper method to store your coffee. The problem here is that you'd all be wrong, and each of you would be wrong in your own special way just like unique little misinformed snowflakes. I don't hold it against you.
   Coffee is among the most traded commodities on earth and the second most important in developing countries, sitting just a few hundred billion dollars behind oil. It's absolutely everywhere, and due to this ubiquity, a great deal of folk knowledge and downright lies have spread like a great conflagration amongst you gullible masses. Being the iconoclast that I am, I feel it's my job to take a swing at these old beliefs with my axe of science, shattering, breaking, and generally just havin' a good old time of it.
   Let's start with an old myth that makes a lot of sense at first glance: 'If I keep my coffee in the freezer, it will somehow last longer.' Most of the people I see doing this are using bad pre-ground coffee in the first place, so I really don't think they are going to notice too much difference anyway. That's beside the point, though. The important thing to note is that when you remove things from the fridge or the freezer, there tends to be a bit of a condensation issue. All of the atmospheric moisture that's lazily hanging out in your home and not even giving you rent money will immediately decide to get really friendly with your ice cold coffee beans. This causes rancid flavors to develop in the coffee by increasing the water content of the bean, normally 8-12%, which chemically screws with the essential oils in coffee. Now think about this: you buy three pounds of coffee because you "jus' love that there sum-matt-ruh", and for the next two months, you take it out of the freezer every single morning, each time further degrading the flavor and sending you into a deep depression, one that, based on your accent, might result in a tragic accident involving two cows, a tractor, and a bottle of Jim Beam.
   The reason you freeze food in general is to prevent growth of mold and micro-organisms in moist foods, and as I stated above, roasted coffee has very little moisture. The main process that ruins coffee is the oxidation of its essential oils, which will happen in the freezer as well, albeit slightly slower. In addition, coffee has the uncanny ability to absorb flavors (hence the abominations of vanilla and hazelnut flavored coffee beans), so imagine your consternation when your delicious Guatemala Finca La Maravilla hits you with the flavor of last week's fish curry. And ultimately, nothing you can do will keep your delicious coffee from oxidizing, going stale, and fading into obscurity, not unlike Vanilla Ice. Much like life, you can spend serious time trying to desperately grasp at a few more days and really killing yourself early in the process, or you can enjoy it right now. It's time to embrace the ephemeral beauty of good coffee.
   That being said, there are plenty of things you can do to extend the life of your coffee. The first and without a doubt the most important is this: grind right before you brew. I know I somehow come back to this every week, but that's how important it is, and I don't hear any of my friends talking about their new coffee grinders, so I assume it didn't sink in yet. Coffee steadily oxidizes, and grinding it increases the surface area immensely, expediting oxidation by a factor of this increase. A coffee bean has about 1 cm^2 of surface area. When ground for standard drip brewing, this increases to about 100-500 cm^2, PER BEAN!!! (low end estimate based on powders of similar diameter, ~700 microns, see Brantley and Mellott, 2000. Yeah, I'm a scientist) For those who stare nonplussed at math and just want a quotable quotable to impress their significant other, this corresponds to a 10-50,000% increase, meaning your coffee is going to oxidize ~100-500 times faster than if you had just left it the hell alone. Thinking about last week's article, imagine how long coffee will last when it's ground for espresso. That's exactly why your barista needs to grind only enough for the present shot!
   Next, keep your coffee in a cool, dry place. Since everyone says this, I'm sure that the cool, dry corners of your home are packed with loads of crap, but try to make room. Too much heat can really wreak havoc on coffee oils, and we've already discussed how moisture negatively affects taste. You can also prevent a lot of oxidation by sealing your coffee in an airtight container, preferably a bag that you can push the air out of. Some coffee shops and at least one website sell resealable (ziploc style) bags that also have a small valve on the front that will let coffee out but not in. Keep an eye out for these as they are a rare and wonderful commodity. S***bucks packages in a variant of these that isn't resealable, which allows them to package right after roasting. However, their bags won't help at all once they're opened.
   The simplest solution, and by far the best, is to buy only enough coffee for one to two weeks. The fact remains that if you purchase more than this, nothing is going to keep it from going bad. Do you buy three months worth of milk when it's on sale? No? Are you honestly so busy that you can't take time to run down to the local roastery and pick up a batch of coffee each week? No, you're not. I know you think you have a hectic schedule, but be honest: you're there 5-20 times a week anyway. Also, it should be two weeks from the roasting date, not the purchase date, so make sure you know when the coffee was roasted. The bins of beans at your grocery store have probably been sitting untouched for months. When I roast coffee, I usually roast no more than half a pound, and I think this is a perfect size for standard coffee purchases. Thus far, I know pretty much all of you, where you live, and other embarrassing personal information as well, and I have to say, you have ready access to good, small-batch roasted coffee pretty much anywhere. If you want to know where to go, I'm more than happy to share my knowledge with you (and possibly return the garden gnome I stole from your front yard). But even if you're sitting in Bumblestump, Nebraska, and the only coffee at Bob's Grocery is made with corn and dirt, there are so many online sources for fresh roasted beans that you'll be able to drink specialty coffee until you're on top of the corn silo screaming at the cows to quit slacking off.