Is There More Caffeine in Light or Dark Roast? (Hint: It’s Neither!)
September 15, 2014
Oh patron, my patron. I need to take this moment to admit that I, your friendly neighborhood barista, have been lying to you. But in my defense, it was quite unintentional.
Long before my undercover investigative coffee-blog writing days, I first believed, as many people, that dark roast coffee held more caffeine. The darker it got, the more my then-unpalated mouth twisted upward, so the torture must have some appeal, right? No, wrong. Then I read the internet and was told that, wa-la little tricksy coffee beans, light roast usurps as the true caffeine-hoarding choice. But it has come to my attention, this is also false. That’s right, I just made two incompatible statements. So what does have more caffeine? The answer is yes. They both do, or rather, can.
Let me explain with a little science. Because, ahem, coffee is a science. *Tips non-existent barista cap*
The taste of dark roast has no correlation to caffeine content. Also, light roast does not “win” because caffeine really cannot truly be “roasted out” of coffee beans. In fact, due to the roasting process alone, there is no real discernable caffeine content difference between light and dark roast coffee.
But one must win. Well, yes, but that depends on how you brew. It always does.
So you see, that since comparatively light and dark roast coffees contain the same caffeine content, they do not contain the same mass. When the green coffee bean is roasted it loses density and gains mass. So it puffs up, like popcorn but without the fluffy delicious exploding aspect. It gets darker in color and flavor, but lighter in weight and physically bigger. See here.
So when you weigh a one pound bag of light roast coffee and a one pound bag of dark roast coffee that means the dark roast bag has more beans. This is because they both have to equal a pound but the bigger dark roast beans have less density and thus weight. (come on, you’ve got it, think of those pound of feathers, pound of steel questions.)
So if a one pound bag of light roast coffee has less beans than a dark roast bag, that means how much caffeine is in your cup depends not on the roast, but the way in which you measure your beans. Let’s assume you’re grinding your own coffee beans for your morning cup of joe. (Or I am, because I’m your friendly neighborhood barista). You have two measurement options:
So if you’re measuring your coffee by scoops, (two scoops please, Jeeves) then a cup of light roast will contain more caffeine because it has a smaller mass and bigger density. (you need more beans to make those two scoops).
But if you’re measuring your coffee by weight. (5 grams of coffee, Jeeves) then dark roast will have more caffeine because you need more beans to make up that weight. (you need more of those larger, less dense dark roast beans to equal 5 grams.)
But I know, I know, now you’re saying “But friendly neighborhood Barista, I don’t grind my own coffee.” Well, (barista snob time) you really should for flavor’s sake, but if you don’t, know the rule still applies. If you’re measuring out your pre-ground coffee by scoops, light roast will contain more caffeine as it took more beans to make those scoops, but if you’re weighing out your ground coffee, dark roast has more caffeine, as it took more ground coffee to get to that weight. Why? Because having itty bitty pieces of coffee still follows the same rules of physics as fully attached coffee beans.
But you want to know the real secret? (Because you just knew there was something more): it really DOESN’T matter that much. Because the difference in caffeine between light and dark roast, no matter how you measure it is itty bitty bitty. If you really want an extra kick, just get an added espresso shot. Or another cup of coffee.
Coffee knowledge compliments of Google, kickinghorsecoffee.com, and life.