Why does lighter roast coffee have more caffeine?
In: Chemistry
The process of roasting the beans is what people think removes the caffeine from them (technically the caffeine’s still intact, but the beans themselves are roasted away and become less dense). Decaff coffee is a bit different, the still green beans are soaked, and a solvent is used to REMOVE the caffeine from them which is different than the concept of lighter or darker roasts having more or less caffeine.
It’s a bit counterintuitive as most foods and flavors are stronger when theyr’e darker, darker typically means more concentrated, so we THINK dark roasts with their stronger flavors would be more potent caffeine.
It really depends how you’re measuring your coffee. By scoops, then light roast has more caffeine because the beans are denser (having not been roasted as long). BUT by weight, dark roast or light roast coffee will have similar caffeine in the same MASS of beans.
EDIT: added some clarification
Coffee shop owner here. The answers here are on the right track but are unnecessarily complicating it.
I’ll try to keep it ELI5 as possible. Roasting does not change the caffeine content of each bean. What it does do is make the bean expand slightly and lose some water weight. So each bean is lighter, larger and less dense the darker it is roasted.
So if you measure coffee by volume (like with a scoop) there are more beans per scoop of light roast than there are of dark roast. Therefore more caffeine.
If you measure by weight, like we do at the shop, 4oz per pot, there are more dark roast beans per 4 oz than there are light roast beans.
But honestly, either way we are only talking about a few beans per pot difference. It’s really not a very significant factor in caffeine content.
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