When it comes to coffee, for some, a simple latte or cappuccino may be ideal, but for the rest of us, it gets a little more specific. Some of us love those citrusy notes or earthy notes, or prefer a particular brewing method, and only like a specific type of roast.
There can be a significant difference between a light or a dark roast when it comes to coffee roasts.
But first, let's talk about what "roasting coffee" means.
The roasting process
Coffee comes from the green fruit seeds of Coffea plants, which don't look or taste anything like the beverage we enjoy and sip on. These green coffee beans are roasted to stimulate chemical, physical, and sensory changes that give them the quintessential aroma, color, and delicious flavor of coffee.
You must wonder how these beans are roasted in the first place. To answer your question, coffee beans are roasted in huge rotating drums in large batches and heated for 5-15 minutes before being cooled and packaged.
Sounds fairly simple, right? Even slight variations in the time and temperature at which beans are roasted can lead to a different final product than desired. One significant difference between the roasting process of light and dark roasts is that light roasts are usually roasted to temperatures between 350 - 400 degrees Fahrenheit for around 10 minutes, while dark roasts are heated for 15 minutes or more at 400 degrees Fahrenheit. The medium roasts range somewhere between these temperatures.
Effects of the roasting process
Evidently, the light roasts require lower temperatures and less time in the roaster as compared to the darker ones.
The roasting process hence has different effects on the roasts. Since roasting or heating the beans removes moistures, the light roasts tend to be denser and moister, whereas the dark roasted beans are usually light and puffy. The roasting process also brings out the natural oils of the beans, which is why dark roasts appear to be more "shiny."
So now we've talked about the stark differences between dark and light roasts; let's get on the most crucial question, which roast has more caffeine?
Caffeine amounts in light vs. dark roasts
There are a lot of misconceptions and rumors about the caffeine levels of both roasts. Some believe that due to the prominent darker color of the bean, the caffeine quantity must be higher as well. While others believe that roasting coffee actually reduces caffeine levels in the coffee, so the light roasts will be higher in the stimulant.
But the truth is, dark roasts can be equal or slightly lower in caffeine than light roasts.
The difference is almost negligible as the coffee is measured by weight rather than volume. As dark roasts puff up and expand due to the longer period of roasting, measuring coffee by volume may affect the overall caffeine levels, but not by much. The color or the look of the coffee itself doesn't pertain to the caffeine content at all.
To illustrate, it was discovered that a sample of coffee brewed with a light roast contained about 60 mg of caffeine, whereas the same amount of dark roast coffee contained about 51mg of caffeine.
So, if you measure your coffee in scoops, the light roast will have more caffeine. This is because these beans are denser and have more moisture. But if you weigh out the scoops or weigh the amount of coffee used, darker roasts will have more affine as there is less mass. One should also note that most Arabica beans vary significantly in the levels of caffeine based on their plant species.
What should you consider?
Since the difference in caffeine levels is not much, to choose between the two, you must take the flavor into account.
Since light roasts aren't exposed to heat for extended periods, they have more delicate and complex flavor profiles. Hence, in dark roasts, the underlying flavors are weak or even lost during the roast process, giving them deep and bold characteristics. The light roasts are also "light" in texture in mouthfeel, while the natural oils in dark roasts increase the viscosity of the coffee, giving it a thicker consistency.
So, the next time you go for a roast, don't go for the caffeine level; go for the taste. Most people follow a simple rule of thumb: It ain't the shade of the bean; just add more coffee to get more caffeine.