Does the roasting process destroy caffeine?

There is a persistent myth in the coffee world that dark roasts have less caffeine because the roasting process 'burns it off.' In reality, caffeine is a remarkably robust molecule. It has a high melting point and is quite stable at the temperatures typically reached during the roasting process, which usually peak between 400°F and 450°F. While some minor sublimation can occur, it is not enough to meaningfully change the caffeine concentration in your cup.

So, why does the myth persist? It likely stems from the difference in how we measure coffee. If you measure your coffee by volume (using a scoop), a dark roast bean is less dense and more porous than a light roast bean. Because the beans are lighter, a scoop of dark roast contains fewer actual beans than a scoop of light roast. If you brew by volume, you are using less coffee mass, which results in less caffeine. However, if you measure by weight—which is the professional standard—the caffeine content remains virtually identical.

It is also important to consider that roasting changes the bean's structure. As a bean roasts, it loses moisture and expands. A light roast is denser, while a dark roast is more brittle and expanded. If you are using a scale, you are accounting for this density change. If you are using a scoop, you are essentially brewing a weaker cup of coffee when you choose a dark roast. The caffeine isn't gone; you just didn't put as much coffee in the brewer.

In practice, if you are looking for a caffeine boost, the roast level is not the variable you should be focusing on. Instead, focus on the dose—the amount of coffee you use per cup. Whether you prefer a light, acidic roast or a dark, smoky one, the caffeine content will be determined by how much coffee you weigh out. Don't let the roast level dictate your energy levels; let it dictate your flavor preference, and adjust your dose if you need a stronger kick.