Does light roast contain more caffeine than a dark roast?

Most coffee lovers would tend to choose a darker roast if they want a caffeine-boasting cup of java. They go along with the general idea that a light roast contains less caffeine than a dark roast. Coffee drinkers with a more sundry experience tend to disagree. So, who is right in this debate? Do you get an extra kick from a light roast, or should you let the beans cook a little longer? Let’s find out!

Caffeine in light and dark roasts: The Myths

You might have heard plenty of people saying how they prefer a dark, even burnt roast to lighter shades of coffee beans, mainly because they believe it has more caffeine. These coffee enthusiasts often go straight for the darkest Robusta they can find.

They are staunch believers of the myth that says coffee beans have more caffeine the longer you keep them in the roaster. According to their experience, that fresh dark roast of java will kick-start their engines and energize them for the full day ahead better than any light roast out there. I, myself used to be part of the dark-roast team until not so long ago.

Fans of lighter roasts would blame that illusion on the placebo effect. In their opinion, caffeine “evaporates” from the coffee beans if you roast them any longer than the first crackling sounds you hear. They have no preference between Arabica and Robusta varietals and gladly pick whichever they may find, as long as the beans have hardly touched the roaster.

You might have already chosen sides before starting to read this article. At this point, you are probably laughing at the ridiculous stance of the rival camp or questioning your lifelong belief about coffee roasts and caffeine. Fortunately, we can use science to get a just result, and the answer might amaze you just as much as it surprised me.

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Science shows which shade of roast coffee has more caffeine

Studies show that the healing process that occurs during roasting has an insignificant effect on caffeine. The substance that we think it will keep us awake during hangover Mondays does not disappear during prolonged roasts. Neither does it increase in quantity if you burn the coffee beans. There will always be the same amount of caffeine in a lightly roasted bean as in a dark roasted bean.

The primary difference in caffeine amount between light roast and dark roast is in the differences between volume and density.

Coffee beans lose mass through water evaporation and increase in volume the longer you roast them. Dark roasted beans have a larger size and less density than lightly roasted beans.

What does that mean for your cup of java? It means that a scoop of light roasted coffee will contain more beans than a scoop of dark roasted beans, and therefore, more caffeine.

On the other hand, if you measure your coffee by weight, and not by scoops, you will get more caffeine from a dark roasted coffee, since its low density incorporates more beans than lighter roasted java to reach the desired weight.

So, there you have it! The way you measure your coffee makes all the difference in the amount of caffeine that you will savor in your cup of Joe. If you measure it by volume, light roasted coffee will have more caffeine. If you measure it by weight, dark roasted coffee will give you the energy kick that you desire.

Does bitter coffee have more caffeine?

Now we know that the difference in caffeine between light roasts and dark roasts depends on how you measure them before grinding and brewing.

But, what about the myth that says that bitter coffee has high caffeine content than a mild-tasting, sugar brew?

We have science solving that one, too, but we will not go into the whole cumbersome explanation here. To put it simply, coffee beans lose most of their water content while roasting. With evaporation, they also lose a significant amount of natural sugar. Therefore, the longer you keep those beans in the roaster, the bitter they will taste, and so will the java in your cup.

So, the answer is no! Bitter coffee only has less natural sugar in it, but it has the same amount of caffeine as a cup of sweet-tasting Joe from lightly roasted beans. It might have a bold character and provide a strong kick in the teeth, but it will not give you more energy than its lighter roasted counterpart.

The final showdown: Robusta vs. Arabica

The final debate over which level of coffee roast has more caffeine surrounds the everlasting battle of tastes between Robusta and Arabica. The former one has a harsh and earthy taste to it, while the latter has fruity aromas and a rather sweet flavor.

Arabica accounts for most of the coffee brands you find on the supermarket shelves. However, if you grind and brew them identically, Robusta will provide double as much caffeine in the same quantity of coffee as its eternal rival.

The Bottom Line

In the end, the difference in caffeine between light roasted and dark roasted coffee depends on how you choose them: by volume, weight, number of beans or coffee variety.

You can go through endless tests combining two or more of these criteria in the quest to find the brew with the ultimate amount of caffeine. Chances are that even then the difference will be negligible and not worthwhile.

Light roast, medium roast or dark roast – there is no wrong pick when it comes to caffeine boost. Your best choice is to worry less about the chemistry within your cup of java and focus more on satisfying your taste buds.

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