Roasting coffee is where science meets artistry. Every choice you make—how much heat you apply, how you control airflow, how long you extend development—shapes the flavour in the cup. Whether you're an experienced roaster or just starting to experiment with specialty coffee, understanding the fundamentals of the roast process is key to getting the best out of your green coffee beans.
The Coffee Roasting Process Explained
1. Drying Phase – Setting the Stage
Green coffee starts with around 10–12% moisture, and the first step is to drive that moisture off. This phase usually takes 4–6 minutes. While it’s not flashy, it’s foundational—get the drying right, and you set yourself up for even development later on.
2. Maillard Reaction – Where Flavour Takes Shape
Once the beans hit 150–180°C, the Maillard reaction kicks in. This is where sugars and amino acids start reacting to form the toasty, nutty, and caramel notes we love. Managing this phase well helps highlight origin-specific flavours—especially important when working with single-origin green coffee beans or microlots.
3. First Crack – The Turning Point
Around 195–205°C, you’ll hear the first crack—a clear signal that things are getting serious. This is when the beans release built-up pressure and start expanding. If you're aiming for a light roast with bright acidity and florals, this is often your finish line.
4. Development Phase – Where You Dial In
The development phase begins immediately after first crack, when the beans have expanded and released pressure. This is a critical time for shaping the final flavour profile. How long you extend this phase determines the balance between acidity, sweetness, and body. A shorter development time typically preserves more acidity and brighter, livelier notes. A longer development leads to deeper sweetness, lower acidity, and more chocolatey or roasted flavours. Managing this stage well ensures the roast doesn’t taste underdeveloped (grassy, sour) or overdeveloped (flat, ashy).
5. Second Crack – Deep Roast Territory
Second crack happens around 220–230°C. This is where things get bold—think dark chocolate, smoky edges, and rich body. Ideal for espresso lovers and milk-based drinks. Just watch your timing—go too far, and you risk losing the bean’s character.
Love a deep, bold cup? Check out our espresso coffee beans designed for fuller flavour and intensity.
Pro Roasting Techniques That Make a Difference
1. Charge Temperature – Starting Strong
The temperature you drop your beans into the roaster at (your charge temp) influences how the roast unfolds. Denser beans, larger batches, or high-moisture coffees might need more energy at the start to get moving.
2. Rate of Rise (RoR) – Steady Wins the Race
RoR tracks how fast your bean temp is climbing. A smooth, declining RoR helps avoid common roast issues like tipping or baking and gives you better control over flavour development.
3. Airflow – Your Hidden Flavour Lever
Don’t underestimate airflow—it’s not just about smoke removal. More airflow generally brightens acidity and cleans up the cup, while less airflow promotes body and caramelisation. Adjust it depending on your goals for the roast.
4. Development Time Ratio (DTR) – Consistency is Key
DTR tells you what percentage of the roast happened after first crack. Aim for:
- 15–18% for light roasts
- 18–22% for medium
-
22–25% for dark
It’s a great metric for keeping your profiles consistent across batches.
5. Cooling & Degassing – Letting the Roast Settle
Once the roast ends, rapid cooling is crucial—it stops the beans from overdeveloping. After that, give them time to degas (usually 24–72 hours) so CO₂ can escape.
Adjusting Roast Profiles to Fit Your Brewing Style
|
Roast Level |
What It Tastes Like |
Best Brewing Styles |
|
Light Roast |
Bright, fruity, floral |
Pour-over, V60, Aeropress |
|
Medium Roast |
Balanced, sweet, nutty |
Espresso blends, filter |
|
Dark Roast |
Bold, smoky, low acidity |
Espresso, milk drinks |
Start With the Right Green Coffee
No matter how good your roast technique is, it all starts with top-quality green beans. From washed Ethiopians to rich Brazilians, the bean’s origin, process, and density will shape how you roast. We’ve got a wide range to explore—from trusted classics to exciting microlots.
Roasting is a Journey—Keep Exploring
The more you roast, the more you learn. With each batch, you refine your understanding of how heat, airflow, and timing interact. And the reward? A coffee that tells a story—from farm to cup.
Need advice, new beans to try, or want to chat shop? Get in touch—we’re always here to support fellow roasters.