If you ask people who care about quality coffee whether to freeze their beans to help preserve their taste, you’ll get two wildly different answers. Some will say: yes, freeze them, freeze them immediately, and you’re a fool if you don’t. Others will say that freezing is always bad, and why would you even consider doing such a terrible thing to your freshly roasted coffee? With such different and strong opinions, is it possible that there’s the middle ground here?
Freshly roasted coffee is a wonderful thing. When you first encounter coffee just a few days out of the roaster, it’s like drinking an entirely new beverage. It’s fairly widely accepted in quality coffee that you should always buy freshly roasted beans and drink them up within a week or two from the roast date. And, I completely agree: fresh beans are always best.
The freeze camp was probably started by Mike Sivetz, the very scientific coffee inventor and researcher that invented the fluid bed air roaster. Mike has some very interesting patents on freezing coffee that lay out the case for freezing. Vastly simplified, the argument looks like this: coffee’s main enemy is oxidation, and chemical reactions slow down as the temperature goes down, and so oxidation is reduced at low temperatures. Mike took it much farther than that of course , essentially proving that freezing measurably slows oxidation down, and also slows the escape of CO2 from coffee as well.
The never-freeze camp says that freezing coffee causes trapped water to expand when it freezes, and this expansion breaks down the cell walls in the beans, releasing some trapped flavor oils and altering its structure.
Puzzled by this split-decision of the coffee industry, a number of years ago I set out to form my own opinion. I took some freshly roasted coffee, and froze some immediately after roasting, and kept some unfrozen. Then, I did day-by-day cuppings of both to attempt to prove to myself which was right.
The result? My opinion is that both camps are right. Freezing results in an immediate slight degradation in taste. But, you can’t fight oxidation, and so slowly the frozen coffee catches up to its unfrozen siblings. My take is that about between days 7-10 out of the roaster, it crosses over, and the frozen coffee preserves the taste and represents the coffee better than the unfrozen coffee.
The other interesting thing I found is that freeze-thaw cycles seem to each have their own penalty. Every time you freeze and thaw, you lose a bit in taste, perhaps something like 5 or so days of sitting idle.
For me, the result is a fairly simple answer: I keep whatever beans I’m going to drink in the next 7-10 days unfrozen, and then I freeze the rest. Then, after I’ve gone through then unfrozen part, I unfreeze a few days worth of beans at a time.