Coffee Science 101: A Beginner’s Guide to Coffee Roasts
Mar 24, 2023 • Arianne Melendres
Mar 24, 2023 • Arianne Melendres
The quality of your coffee isn’t totally dependent on the type of beans in your cup. While the bean can absolutely make all the difference, you can’t forget about the roasts.
The slow and delicate process of roasting adds another layer to the distinctness and complexities to the adoring flavors and aromas of everyone’s cup of joe. There are four major ways you could go about it: Light, Medium, Medium-Dark, and Dark.
Now that we’ve all settled by the morning sunlight and are warming up to the day, shall we begin roasting?
First of all, let’s define what roasting actually is.
The green coffee beans that one gets from de-pulped and dried-out coffee cherries aren’t exactly ready for brewing right away. Roasting is a heating process that turns those green beans into brown and fragrant beans that everyone is accustomed to seeing.
This is where the beans get their aroma and flavors; the temperatures the beans are exposed to, the amount of oil that rises above their creases, and the colors that develop. Without roasting, everyone’s coffees would smell earthy and grassy—like tea.
One common misconception is that darker roasts have more caffeine due to their stronger flavor. In reality, roasting actually breaks down some of the caffeine molecules, so darker roasts may have less caffeine per bean than lighter roasts.
Generally, the trend is as follows: the longer the roasting process, the lesser the beans’ acidity, the darker their colors, and the lesser their caffeine content by volume.
With that in mind, let’s dive into it!
Not a fan of bitter flavors? Perhaps light roasts may be more to your liking. Amongst the four major types of roasts, light ones are roasted for the least amount of time, from internal temperatures of 180℃ to 205℃
With such mild conditions and picked right after the first crack, their light colors and dry surfaces become prominent. Almost no oils are present atop their cracks, and the fruity and herbal flavors of coffee shine the brightest. Perhaps one could even say that they maintain the real characteristics of the beans because they haven’t been processed for long.
It’s true that light roasts have the most acidity among the roasts, but that’s not necessarily a bad thing. The acidity of these roasts makes them taste crisp and almost tea-like, producing a multilayered complex flavor that refuses to overwhelm its drinkers. For the final treat, light roasts make for a mild cup of coffee spilling with a floral, fruity aroma. Perfect for a cold brew, don’t you think?
Prefer nutty and chocolate-like notes in your coffee? Medium coffee roasts are for those who love having some sort of balance in their life. Picked after the first crack and right before the second, medium coffee roasts are exposed to just the right amount of heat. Perfect for those who love the taste of tradition.
Heated at internal temperatures of 210℃ to 220℃, their surfaces are mostly dry but have a tint of those caramelized oils that some crave for.
Compared to light roasts, these actually have sweeter profiles and are smoother on the palate, complementing the bitter notes of the coffee. All in all, they’re a great balance of preserving the natural taste of the coffee beans whilst reaching out to the depth of longer roasts.
And if light roasts have a complex flavor profile, medium roasts have a sophisticated aroma. Their scents are strongly reminiscent of cherry and maple, but remain comforting with subtle salty, sweet, and bitter aromas of caramel and roasted nuts.
Like to swerve a little bit from the normal? Medium dark coffee roasts might be up your alley. These humble coffee roasts thrive during or right after the second crack, when the caramelized oils of the coffee beansfinally appear on the beans’ surfaces.
They take a few minutes of roasting longer than medium roasts, but a little patience goes a long way. Sitting at internal temperatures of 225℃ to 230℃, the beans are full of warmth and surprises.
Characterized by a fuller and richer flavor, medium-dark coffee roasts have a slightly spicy and tangy taste, juxtaposing the caramel and chocolate notes that come from the remains of a signature medium roast. There’s some smokiness in there, too, with signals of low acidity levels.
Regulars at Starbucks are well-accustomed to the taste and aroma of dark coffee roasts. The strong and subtly bitter flavors may be harsh for some, but many greatly welcome the flavor for the kick that comes from the smokiness.
Longer roasting time denotes smaller amounts of caffeine, but no one can deny that dark roasts have richer and fuller tastes. Roasted at 240℃ to 250℃, they’re toasty and decadent. The bold flavor is probably why the lines at Starbucks are always so long, too.
That’s not the only thing that these coffee beans are known for, however. One will also notice that dark roasts have a sweet and buttery aftertaste. This is largely due to the number of oils that surface atop the beans due to the long amounts of roasting time. Not only that, its strong aroma is well-reminiscent of late study sessions at cafes with friends.
With nostalgia and uniform flavor across the cup, dark roasts are perfect for drinks with cream and milk.
In general, the lighter roasts preserve more of the natural characteristics of the coffee beans, while the darker roasts have stronger flavors and less acidity. Ultimately, the choice between these roasts comes down to personal preference.
When’s your next coffee date? Trying out all the types of coffee roasts together sounds like a good idea, doesn’t it? Maybe you’ll find your new favorite drink while you’re at it!
In a quasi-steady state, Arianne is a journalist who loves to smile, read books, and talk about science.
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