We know that water is wet, but that fact alone isn’t enough to capture water’s immense power. That power is evident in coffee, not simply in the cup but also in the seeds themselves: Water activity (Aw) is the relative equilibrium that exists (or doesn’t exist) between the vapor pressure inside a food or a coffee seed as compared with the surrounding humidity or environment. In perishable foods, it is a significant measure for the sake of safety and the prevention of food-borne illness, but in coffee, it’s a significant measure…why, exactly?

Starting in 2012, the Cafe Imports sensory analysis department, led by director Ian Fretheim, set out to start collecting and monitoring water activity in green coffee in the hope that “it would provide a more insightful measurement than moisture content, specifically with regard to predicting the shelf life of coffees. We hoped to answer (or at least partially answer) the question of why some coffees arrive as purchased and some do not.”