Light vs. Dark Roast: Which Bean Packs More Caffeine?
Pop quiz: If you want the most caffeine out of your coffee, should you go with a dark roast or a light roast? If you answered dark roast, you're in the majority, but unfortunately you're incorrect. Don't celebrate just yet if you answered light roast, because that's not right either. The truth is, if there's any difference in caffeine levels between dark and light roast beans, it's negligible. Diehards in both camps have insisted for years that their roast is the real deal, but it turns out that it all comes down to how you measure.
Not Black and White
Before breaking out the scales, it's worth taking a look at the feuding camps. When people talk about a strong cup of coffee, they're usually referring to how bold it tastes. This may not mean that the varied flavors are more pronounced, but that they're more intense altogether. Since dark roasts tend to deliver this kick in the teeth more than light roasts, it makes sense to call them stronger, which may lead some to assume that they're also more caffeinated.
Light roasts, on the other hand, may seem weaker just because of the various meanings of the word "light." They also tend to taste more delicate and floral, which could insinuate that they pack less power. Those who claim that light roasts have more caffeine seem to have the facts to back up the claim. Since roasting a bean for longer brings more oils to the surface, it could be assumed that some caffeine may escape and be burned off in the process. However, caffeine doesn't react too much to any temperature under 600 degrees, according to Scribblers Coffee Co., more than 100 degrees more than coffee's usual roasting temperature. Another change that happens during roasting may explain how the great caffeine debate started in the first place.
Weights and Measures
When a coffee bean is roasted, it loses much of the water locked inside, which makes it less dense, according to Coffee FAQ. At the same time, the fibers of the bean expand, making it grow in size. Since light roast coffee is exposed to less heat, it stays relatively smaller and denser. So, if you measure one batch of dark roast beans and one batch of light roast beans by weight, the scoop of dark roast will have a few more beans in it, and thus more caffeine. But if you measure by volume, you can squeeze more light roast beans into your coffee maker, for a higher caffeine content in the final cup. The difference is still negligible, so it's best to just enjoy your brew without worrying about which will give you the best buzz.