Caffeine: Light versus Dark Roasts
There’s a widely held assumption in coffee discussions that light roasts have more caffeine than dark roasts. I’m here to dispel this myth.
A couple weeks ago, I ran a quick poll on social media asking people about coffee and caffeine. I didn’t do this to point out who was right or wrong, but to get a sense of how people look at coffee and caffeine. I asked people which coffee they think has the most caffeine: Zoomies, one of our lightest roasts, or Muddy Paws, our darkest roast. The popular opinion vote: light roasts have more caffeine (in the poll this won 2:1).
This is such a misassumption that I (kind of) hate to bust that bubble. But here is it:
Light roasts have less caffeine than dark roasts. Here are the facts:
Caffeine does not ‘burn off’ during the roasting process. In fact, it doesn’t break down/ melt until temperatures reach approximately 455°F (235°C). As reference, Muddy PawsTM the darkest roast we currently offer at Fetch, reaches a maximum temp of 424°F (217°C).
Why dark roasts have more caffeine than light roasts
The reason dark roasts generally have more caffeine is because green (unroasted) coffee has a percentage of moisture before roasting (typically 10-12%). The longer a bean is roasted, the more moisture it loses. Therefore, darker roasted coffee beans weigh less than lighter roasted coffee beans. The most consistent way to brew coffee is to the weigh the beans. Due to the moisture loss, 20 grams of light roast has less coffee than 20g of dark roast, so you are effectively brewing more beans within that same weight of roasted beans.
How much does this matter and what other factors should you consider?
The difference of caffeine levels between light and dark roasts is pretty minimal. Thanks to the team at the Oregon State University Food Innovation Center who tested our beans, we have the numbers to prove it:
Caffeine Content in mg/100g of coffee
Muddy PawsTM (dark roast) 1510
Squirrel!!® (Medium Roast) 1400
ZoomiesTM (light roast) 1290
Keep in mind this is for 100g of coffee before extraction. Unless you actually eat 100g of coffee beans (probably not a great idea) you won’t get this much caffeine. The numbers above simply demonstrate the difference in roasts!
Other factors to consider when you’re talking caffeine:
1. Your brew method matters. How much coffee you put into your brew, and the extraction time impact how much caffeine ends up in your cup. Caffeine is one of the many TDS (total dissolvable solids) that make up a cup of coffee, The longer they sit in water, the more caffeine will extract. But the overall addition in caffeine probably wouldn’t justify the less pleasant taste a longer brew would extract!
2. The species matters: Thie study was conducted with all arabica beans. This is the species used for specialty coffee. The species robusta has a much higher caffeine content, but because of that higher caffeine content, it is a much more bitter product.
3. Arabica beans do vary slightly as well across varieties, but it is an extremely small percentage, so we aren’t addressing it at least in this post.
So, what does all this mean?
Dark roasts have a little more caffeine than light roasts, but it is minimal so drink the roasts you love for the flavor. If you really want more caffeine, use a bit more coffee in your brew, or better yet, have a second cup. And enjoy!