☕ Coffee Journey - Dark Roast

Welcome back to our Coffee Journey!

As promised, we're going to talk about the roasting process of coffee beans. This procedure contributes a great deal to how the coffee will ultimately taste, because while roasting, we develop 800 - 1000 different aroma compounds, which make the flavor of the coffee.

There are four stages in coffee roasting:

  1. Drying
  2. Browning
  3. Roasting
  4. Cooling

Even though the coffee beans are being dried at their farm, there's still 8 - 12% of moisture left in the bean to preserve its quality, so there needs to be a final drying phase at the roasting plant. 

You will drop the beans from above into the drum, where the coffee goes into drying for about five to seven minutes. At the end of this process the temperature is at 160°C (320°F)

With the browning stage the coffee beans will begin to smell like toasted bread.

Have you ever heard of the Maillard reaction? Check out my post about two day cookies :-)

This is at work here. The natural sugars and amino acids within the beans start to react and create a distinctive color and flavor characteristic.

Photo by Yanapi Senaud on Unsplash

When you roast coffee, the longer you roast it, the more you will degrade acidity and caffeine. But also, the longer you roast coffee, the more bitterness you typically will get - just like with caramel. Take it too far, and you've burnt it. 

With "dark roast" people mean the coffee beans are taken to the point when you're beginning to see oils on the surface of the beans. During roasting a lot of pressure builds up inside a coffee bean, initially that will cause it to pop or crack relatively early in the process. Usually the first crack happens somewhere between seven and eight minutes.

The beans double in size, crackling as they expand. They are now light brown.

As you keep roasting the popping will happen again.

However, for light roasts, we will end the development right after the first crack. They'll have reached an internal temperature of 180 - 200°C (365 - 400°F)

For medium roasts, you want to keep roasting for a few minutes longer until they reach 210 - 220°C (410 - 428°F)

For espresso and dark roasts hold the beans inside the drum right before or immediately after the second crack. This will be after 11 - 15 minutes, and temps will reach 220 - 250°C (464 - 482°F)

Source: Starbucks

During my immersion with Starbucks we experienced this, both at the roasting plant and in a "coffee lab". Not unlike popcorn you will hear several seconds of popping and crackling. Quite fun!

All of that time, this internal pressure in the bean is pushing oils to the surface, which is why darker roasts look much oilier - "shinier" - on the outside. 

At this point, coffee is released from the roster and into a circular area below the roaster over a fan for cooling. During this process, there's time to remove quakers (under roasted beans) or scorched beans (over roasted or burnt)

Some people like "French Roast". This is the darkest roast I have ever tasted. It smells like burnt rubber. Yuck!

One of the challenges of darker roasts is that this process gives you a more porous coffee bean. You can literally crush it with your bare finger. Being more porous exposes it to more air, and ultimately dark roasted coffee will stale much faster. 

Meaning, you should be using your dark roast within two or three weeks. Depending on the amount of coffee you typically purchase, this should not be a problem, right?

Now let's take our roast knowledge to the next level and talk about grind size.

When you roast a coffee bean darker, it's easier to extract the coffee, however, there's less soluble material in darker roasted coffee, because some of it went away as smoke.

So you want to grind your darker roast notably coarser.

Photo source: Alternativebrewing.com

Now let's talk about brew ratios.  How much water for how much coffee?

It comes down to density: There are a couple of things that can affect the density of your coffee bean, such as the elevation (how high the coffee was grown) the varietal of coffee, and then there's roast.

As a rule of thumb, however, the recommendation is 180ml of water for every 10g of ground coffee. If your brain does not do metric system, go with 6oz of water and 1/8 measuring cup (or 3.75 teaspoons) of ground coffee.

That was a lot to process. Your head must be spinning. In German we literally say "mir raucht der Kopf", my head is smoking. I guess our brains are undergoing some kind of roasting process as well ;-)

Now on to the fun part: 

Tell me where in the U.S. you live, 

and I'll tell you what kind of coffee roast you like!

If you're according the stereotype, that is. I've been told that people at the East Coast, specifically in New England States, like a lighter roast, whereas the West Coasties prefer a darker roast. Obviously this is also why Dunkin Donuts is more successful out East with their coffees than at the West Coast? 

Is it true? You tell me!

PS: If you're interested about the coffee bean's journey prior to the roasting process, keep your eyes open for the upcoming post on green beans!


  1. Hmm. I drink my coffee black and generally prefer dark and bold flavors, but I prefer DD over SB because I find SB tastes a bit “burnt” and metallic. My fav lately is Tim Horton’s dark roast which is available in Shanghai where I live. Costa coffee is also pretty good. I’m from New England originally, by the way.

  2. How interesting! That's quite a process just to get it ready for a cup of coffee!

  3. Thanks for sharing this information. We recently switched to dark roast but did not know that we should grind it to be course.

  4. So, does this mean that a lighter roast will taste less bitter? I really, really want to like coffee! I love the smell and pretty much everything except the flavor, which seems way too bitter.

  5. You sure know your coffee, Tamara! That's alot of learning. I do admire people who take the time with their 'coffee'. I am the opposite. I should take more time. We live near a coffee place and can smell the roasting. Before knowing, I thought boy somebody sure burn their porridge alot.

  6. I'm really enjoying your series Tamara, and learning lots. I definitely prefer a medium to lighter roast - and since I'm in Chicago between coasts, I think that bodes well for the accuracy of that survey. :-) I hadn't realized grind optimization had anything to do with roast - I thought it was more to do with how it was brewed. All this talk of coffee has me craving a cup, and I'm headed off for one.

  7. Well your theory is wrong for me anyway. I'm on the West Coast but definitely prefer light to medium roast. No French burnt in this house.

    Janet’s Smiles

  8. I'm not a coffee drinker but my husband LOVES his coffee. Right before we go to sleep every night he says, "I get to wake up and drink coffee." I'm laughing as I'm typing but I'm serious. He also loves his half and half - no sugar but half and half. We live in Alabama.

  9. I live in New England. But having spent considerable coffee-drinking time in Europe, I do want my coffee to taste like coffee!

  10. My husband actually really loves the dark roasts although you are right about New England - it's Dunkin' country out here. Weekends In Maine


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