The reason for coffee going stale is related to the way it decomposes in its different forms. Coffee goes through four processing stages: green beans, roasted beans, ground coffee, and brewed coffee. Green coffee beans can remain fresh for up to a year, while freshly roasted coffee beans lose their flavor after a few weeks. Brewed coffee goes stale after a few minutes, and ground coffee stale after only 45 seconds.

The aroma and flavor of coffee are attributed to the behaviour of its aromatic compounds. The volume of these compounds increases significantly during the roasting process, which enhances the flavor. However, the compounds are volatile, which means they tend to sublimate from solid beans or grinds, as well as brewed coffee, into the air.

Ground coffee has a larger surface area than whole beans, resulting in the compounds escaping faster from the coffee. The aromatic compounds that give the coffee a unique flavor are lost in just forty-five seconds. Therefore, to brew a great-tasting cup of coffee, it is ideal to grind the beans just before brewing.

If you're interested in brewing fresh coffee at home or on the go, we recommend starting with the HARIO Mini Mill Slim Pro. Its slim and durable body makes it a great choice, and the ceramic burrs guarantee a consistent grind size for a consistently delicious cup of coffee!

Enjoy your coffee!