What Your Roast Date Isn’t Telling You
If you’ve ever browsed the coffee aisle at the supermarket, I’m sure you’ve noticed the variety of dating verbiage on the packaging. Some will say “best by” or “use by”, or “fresh until”. Truthfully, these dates can be a helpful guideline when you’re purchasing a loaf of bread or a gallon of milk, but they don’t tell you anything about the freshness of coffee.
How can you tell if your coffee is fresh? You may have noticed that most reputable specialty coffee roasters will include a roast date on every bag. Since coffee doesn’t expire, or become harmful after sitting on the shelf for too long, this is the only metric we can use to gauge freshness without the benefit of tasting/smelling the coffee. It is much more helpful to know where the starting line is with coffee, than it is to guess at an arbitrary finish line.
When does coffee reach its prime? I often encounter people who are seeking the freshest of the fresh beans. They want the coffee that just came out of the roaster yesterday (or this morning). I completely understand this appeal, but coffee needs time to rest before we attempt to extract the flavor out of it. During the roasting process, the cells of the coffee bean are packed full of CO2. When we grind and brew coffee, we’re trying to get hot water into those same cells. If there is too much gas trapped inside, the water will not be able to sufficiently extract flavor from the coffee before passing through the coffee bed, and will result in an under extracted cup.
Find the sweet spot. Each coffee and roast profile will behave differently after the roast. Some will degas more quickly than others, but it can generally take up to a full week for the coffee to degas and “settle in”. During the first week, coffee is likely to taste very different from day to day. In addition to losing CO2, the coffee is also slowly losing aromatics. This is one reason that we seal our coffees in airtight bags with a one way valve. The CO2 is able to escape, but oxygen is unable to get inside and degrade the aromas present. The coffee will be at its absolute best when it has lost a sufficient amount of CO2 without losing too many of its volatile aromatics. The roast date is simply telling us when this process began. Some coffees open up beautifully after 5 or 6 days, and maintain their quality for 3-4 weeks. Others reach their prime in 7-10 days.
The next time you consider buying a bag of coffee that was roasted a week ago, try not to think of it as “week old coffee.” The reality is, this coffee is probably just starting to head into its prime state for consumption.