There’s more to it than meets the eye.
The roasting process of coffee affects the not only the taste but also the:
- caffeine content
- flavor bouquet
- most any other factor you can think of
Coffee is from a plant of which the beans are roasted to bring out the flavor we enjoy – the flavor that’s made it the third most popular beverage in the world.
The obvious fact is that a short roast duration makes it a light roast; a long roast duration makes it a dark roast. A medium roast duration makes it a… yeah you get the point.
The beans of the Coffea plant are green before they are roasted and transformed into the wonderful beverage we call coffee, becoming darker and darker through the procedure.
As they are roasted, the beans undergo 2 “cracks” as they simmer on the roaster, similar to how popcorn pops when it’s cooking.
These cracks are indicators that help reveal when coffee is a light roast, medium roast, or dark roast.
Just after the first crack is light roast, approaching the second crack is medium roast, at the beginning and after second crack is dark roast.
Here are the approximate bean temperatures at different roasts
- Light Roast: 385° – 405° F (196° – 206° C)
- Medium Roast: 410° – 430° F (210°- 220° C)
- Dark Roast: 435°- 473° F (225° – 245° C)
See if you can guess which roast these beans are in the picture below just by looking… I have another picture at the end that reveals the answer.
So if you’ve wondered what’s the difference between light and dark roast coffee, here are some key differences explained:
Many people have a preference to which roast they prefer. As I’ve written before, my personal favorite is dark roast coffee. If you’ve only tried one or two roasts, give them all a try and see which one you like best.
Generally, the different roasts have similar flavor characteristics.
Light roast coffees will usually contain the following flavor characteristics:
- Toasted Grain
Normally you won’t find those flavors in dark roast coffees. Although, there are exceptions and I have to use words like “usually” or “typically” because coffees can be different!
These are not hard and fast rules, just generalizations.
Light roasts contain more of the “origin character” of the beans – all the factors that give its distinct flavor such as altitude, soil, weather conditions, and country of origin.
The longer it is roasted, the more these flavors profiles are diminished.
Dark roast coffees will typically contain the following flavor characteristics:
These are just some of the flavor profiles you would generally find in different roasts.
Coffee undergoes the Maillard reaction and other chemical reactions that take place when food is roasted/cooked which cause it to become more browned or charred, which is why darker roasts usually have a flavor profile which is more robust and smokey.
But a light roast coffee can certainly have nutty or smokey notes to it, and a darker roast could very well have floral or fruity notes to it. This is just a guideline.
This is a straightforward concept. But it’s one of the main differences most people notice in light vs. dark roasts.
Light roast coffee has a higher acidity to it. Conversely, dark coffee has lower acidity.
Some of the acids found in coffee are citric acid, malic acid, acetic acid, phosphoric acid, and chlorogenic acid, just to name a few.
All these are key in the coffee’s flavor profile and characteristics. But in lighter roasts, the acidity is more pronounced, resulting in a pungent taste.
In darker roasts the pungency of the acid is lessened, but the original flavors which result from the acid is also dulled.
This is one of the main reasons I prefer dark roast coffee, because I’ve learned over some years of coffee drinking that I prefer less acidity in coffee.
After the taste and the flavor profiles, this is one of the main things people notice about coffee when they taste it.
If your taste buds don’t notice it, your stomach maybe will, as higher acidity can sometimes cause an upset stomach.
The Caffeine Level
Just like the acidity is roasted away as the coffee becomes a more dark roast, so does more of the caffeine content get roasted out in darker roasts.
I have heard many people casually mention this fact in passing, especially when I’ve worked at coffee shops. I’ve been under the impression that it’s a big difference.
However, it wasn’t until I did more research to find out that the difference in caffeine levels is minuscule… it’s tiny. It could be .02%. Yes, you read that right.
I don’t know about you but my body definitely can’t tell a .02% difference in caffeine!
It’s hard to come across exact numbers as to the difference of caffeine content.
I’ve done a lot of research on it and reports are conflicting, so it’s difficult to make factual statements about the caffeine levels.
But it appears that there is almost no difference.
Another important point in the caffeine discussion is that the density of coffee is yet another thing that changes in the roasting process.
This is, in fact, even more important than any caffeine level variance because the change in density is more pronounced than any change in caffeine.
Due to the fact that light roasted coffee beans are smaller and more dense than dark roasted beans, if you have a “scoop” of each then the light roast coffee will have more caffeine because there’s more… COFFEE! More coffee means more caffeine.
The fact is that per volume, the caffeine content is pretty stable throughout the roasting process.
Also important to understand is that there are other factors in how much energy boost a particular roast or coffee gives than just caffeine.
I did tell you in the beginning it was complex.
This is a more subtle difference in the roasts, but it’s one that the coffee tasters and connoisseurs will appreciate.
We describe the “body” of coffee as how full and thick or how light and hollow the coffee feels in the mouth, or its overall texture.
This one isn’t just proportional to the roast like the acidity or density. It actually increases in the start of the roasting process, but at the second crack it thins out again.
A light roast will have a light body, increasing up to a medium-dark roast which has the fullest body, then at dark roast it has a light body again.
A full-bodied coffee will feel heavy in your mouth, and a light-bodied coffee will feel more thin and liquidy in your mouth.
I personally don’t have any preference about the body or mouthfeel of coffee. It’s nice to experience a different mouthfeel with different flavor bouquets.
But once you are aware of the body, it can be very enjoyable to take note of how you perceive it when you try new coffee.
A Day And Night, Dark And Light Difference
These are just some of the differences between light, medium and dark roast coffees. It really is a fascinating study to look into the changes that take place with different roasts of coffee.
To sum things up, here are some key differences:
- The acidity is higher in light roast coffee, and lower in dark roast coffee
- The caffeine content is maybe higher in light roast coffee than dark roast (although, this is up for debate)
- The origin flavor is more pronounced in light roast and is replaced more with a roasty flavor in dark roast
- The body increases (feels heavier/thicker) in the roasting process until dark roast, and becomes lighter after second crack
Do you have a roast preference?
Do you ever notice a difference in the energy boost of light and dark roast coffees? If you want to tell me about it or leave any other questions/comments, please feel free to write them below!
And here’s the answer to what kind of roast the beans were from the photo at the beginning. If you guessed dark roast, you got it!
p.s. here’s another great article about the difference between light and dark roast coffee!