Does roasting coffee remove caffeine?

There is a persistent myth among coffee drinkers that darker roasts contain less caffeine because the roasting process 'burns off' the stimulant. In reality, caffeine is remarkably stable at the temperatures used in commercial coffee roasting. While a bean might lose 15-20% of its weight during roasting—mostly through water evaporation and the loss of organic matter—the absolute amount of caffeine in a single bean remains virtually unchanged.

When we talk about caffeine content, it is important to distinguish between measuring by weight and measuring by volume. Because dark roast beans are less dense and larger than light roast beans, a scoop of dark roast coffee contains fewer individual beans than a scoop of light roast. If you measure your coffee by volume (using a scoop), you might end up with slightly less caffeine in a dark roast simply because there is less coffee mass in the scoop. However, if you measure by weight (using a scale), the caffeine content between light and dark roasts is essentially identical.

Coffee chemistry is complex, but caffeine is not the volatile compound that disappears during the Maillard reaction or caramelization. The changes you taste in a dark roast—the increased bitterness, the reduction in acidity, and the development of smoky or charred notes—are the result of the breakdown of sugars and the formation of new aromatic compounds, not the degradation of caffeine. The caffeine molecule is robust enough to survive the entire roasting cycle.

In practice, if you are looking to manage your caffeine intake, the roast level is not the tool to use. Instead, focus on the species of the coffee (Robusta contains nearly double the caffeine of Arabica) and the dose of coffee used in your brew. Whether you prefer a light, medium, or dark roast, the caffeine content will remain consistent provided you are weighing your grounds. If you want less caffeine, the only reliable method is to choose a decaffeinated coffee, which undergoes a specific process to remove the stimulant before the beans are ever roasted.