Dark roast coffee beans vs light roast. Which has more caffeine?
Ill admit, in my younger days i really didn't care what kind of coffee made it into my cup every morning. I would drown the coffee in so much milk and sugar it tasted more like a milkshake anyways. As I progressed through my coffee journey, I slowly began to develop a taste for coffee itself, and have now been drinking it straight black since my college days. My morning ritual went from brewing up a quick pot of department store ground coffee to buying gourmet coffee beans online and grinding them fresh everyday each morning.
Of course, while in college I was pretty much living on the stuff, trying to keep myself awake during my lectures after some pretty long nights. I found myself, more often than not, going with a dark roast (Italian or French) because it was thick and dark, which I assumed meant more caffeine. The darker and thicker the coffee beans, the higher the caffeine content, right? Wrong.
In fact, light roast coffee beans actually have a higher caffeine content when compared to dark roast coffee beans. It's not because the coffee beans used for roasting are any different, it comes down to the density of the ground coffee that is used for brewing. The process to roast coffee beans into dark roast is much longer than the light roast process. The coffee beans that are roasted longer are less dense, therefore, have less caffeine per scoop when compared to coffee beans that are roasted less.
Now, if you were to take coffee beans that were light roasted and take coffee beans that were dark roasted and weigh out an equal mass, the coffees would have the same caffeine content. However, the pile of dark roast would be larger in terms of volume because it takes a larger amount of dark roast to equal the same mass of light roast.
This is all fun information, but in all likelihood, at the end of the day the difference in caffeine content of coffee beans in a dark roast and a light roast is so minimal we can't even tell the difference. Just enjoy the roast you prefer!