Everyone wants their coffee to taste great, and so everyone wants their coffee to be as fresh as possible. You might think that your coffee will taste its absolute best straight out of the roasting drum. This makes sense when you consider other consumable goods’ freshness, but coffee operates a little differently. There are some common misconceptions about coffee and its freshness that we are going to try to debunk once and for all.
The first myth to bust is that the best tasting coffee is the best smelling coffee. Your coffee absolutely should have aroma when you brew it, but if you only measure freshness by aroma, you’ll end up brewing coffee much too soon. Coffee aroma begins depleting immediately once it’s roasted, but coffee fresh from the drum will not taste nearly as good as it can at its peak. If you open your bag of coffee and it has no aroma, it is likely stale and has sat for too long. But aroma is not the best or most scientific way to determine your coffee’s freshness.
The second myth is that coffee is actively losing freshness once it’s roasted. This is not necessarily true, but it depends on the way you look at it. Coffee needs time to taste its best, but that time period in the first week or so after roasting shouldn’t be considered a loss in freshness. It should be looked at more as an evolution of flavor. Each day in that time period will produce a very different cup of coffee.
Coffee loses freshness from an aroma perspective and a carbon dioxide perspective. A chemical reaction occurs during the roasting process that releases that signature coffee smell we all know and love. This is the same type of chemical reaction that happens when you caramelize onions. Also during roasting, carbon dioxide is created and then begins to release from the beans in a process known as degassing.
Coffee starts degassing quickly after leaving the roasting drum, and grinding the beans accelerates the degassing process. Water has to be able to soak into the ground coffee in order to extract the flavor, and if those grounds are surrounded by too much carbon dioxide, then the water can’t penetrate the coffee and you’ll be left with coffee that tastes weak and sour.
Coffee does not technically expire in the traditional sense of the word. If you were to wait a year after its roast date and then brew a cup, it would not be an undrinkable disaster that makes you sick. More or less, coffee goes stale rather than expires.
Unfortunately there is no one size fits all rule for determining the exact amount of time your coffee should sit before you brew it, but with a little experimentation you can determine the time frame that works best for you and your tastes. A good time frame to try within is 4-10 days. Each coffee is different based on its roast profile and origin. The most important tips for coffee freshness are proper storage and making sure you buy small enough quantities of coffee so you can drink it before it loses flavor and peak freshness.