Welcome to the Roast Show: A Beginner’s Guide to Coffee Roasting

We're about to take a journey into the wonderful, slightly chaotic world of roasting coffee.

What Even Is Coffee Roasting?

At its core, roasting is the magical (scientific) process of transforming raw green coffee beans into the complex, aromatic flavor bombs that make your morning bearable.

Roasting is both an art and a science. And like anything scientific, it involves heat, reactions, and a lot of data.

The Basics: Endothermic vs. Exothermic

Let’s get a little chemistry going.

• Endothermic: In the early stages of roasting, beans absorb heat. This stage drives off moisture and starts those slow, caramelizing reactions.

  It's all about subtle bubbling and transformation. Consider it plot development.

• Exothermic: Around first crack, the beans flip the script and start releasing heat. This is the exothermic phase. It’s loud, snappy, and your cue that things are about to get roasted.

The Roasting Timeline: Don’t Blink

1. Drying Phase (~0–5 min): Beans start at room temp. They heat up and lose moisture. Your roaster might smell like hay. Don't panic. That’s normal.

2. Maillard Reaction (~5–8 min): The party starts. Sugars and amino acids combine, turning the beans golden-brown. This is where flavor is built. It’s also where the roaster should start paying close attention.

3. First Crack (~8–10 min): Snap, crackle, pop, baby. Internal pressure causes the beans to crack audibly. This is the defining moment when light-to-medium roast profiles emerge.

4. Development Phase: After first crack, you’re in charge of how far you go. Stop too early and you’ve got sour, grassy notes. Go too long and... well... hello, charcoal.

5. Second Crack (~12–14 min, depending): Another crack, but more like snap-crackle’s angsty older sibling. At this point, the coffee is well into dark roast territory. Oils may appear on the surface. Proceed with caution.

Rate of Rise (RoR)

If you’re serious about roasting, you’ll want to know your Rate of Rise. This is basically how fast the bean temperature is climbing over time.

A smooth, declining RoR curve is the holy grail. Spikes and stalls are your enemy. Why? Because uneven RoR means uneven development. It's the difference between a symphony and a kazoo.

Roast Levels: Because Names Matter

Here’s a cheat sheet for roast lingo you’ll hear in the wild:

• Light Roast: Pulled shortly after first crack. High acidity, floral and fruity vibes. For those who sip and analyze.

• Medium Roast: Balanced acidity and body. Common crowd-pleaser. Still has nuance without the aggression.

• Full City Roast: Just before or right at second crack. Chocolaty, rich, and starting to show dark roast character without tipping into bitterness.

• Full City Plus: Into second crack. Oils appear, darker flavors (smoke, baker's chocolate). For people who don’t flinch at a little edginess.

• French Roast / Italian Roast: Way past second crack. Smoky, oily, and bitter-sweet.

Other Roasty Tidbits

• Development Time Ratio (DTR): The % of time spent post-first crack relative to the entire roast. Aim for around 20-25% for most profiles. Too short? Sour city. Too long? Ashy regrets.

• Color Scores: The SCA uses color meters (like Agtron or ColorTrack) to classify roast degree. Light roasts fall in the 60–70 range, dark roasts 25–35.

• Bean Density Matters: High-altitude beans are denser and can take more heat. Lower altitude beans? Treat them gentler, or they’ll break down faster than a Jenga tower in a windstorm.

• Decaf Density: Please be cautious. Decaf beans have already been processed twice: once to remove caffeine, and again to dry them back to a roastable state. That means:

  • They’re more brittle.

  • They look darker before roasting (especially Swiss and Mountain Water Process).

  • They're often less dense, depending on the origin and decaffeination method.

More Tips for Roasting Decaf:

• Charge Lower Than Normal

  Start with a lower charge temp than you would for the same origin non-decaf—maybe 10–20°C lower (~20–40°F). They don’t need that aggressive early heat, and they’re more prone to scorching.

• Use a Slower, Smoother RoR

  Avoid aggressive Rate of Rise in the first few minutes. Decaf roasts are best approached with a steady, declining RoR. They already lack some of the organic material that helps develop complex flavors under high heat, so you want a slow, steady ramp to encourage even development.

• First Crack Is Sneaky

  With decaf, first crack can be quieter or delayed, and it’s easy to miss. Some roasters call it a “whisper” instead of a crack. Use your temperature data to guide you—not your ears alone. If you normally hit FC at 196°C (385°F) for that origin, aim close to that and be ready for subtleties.

• Shorter Development Time is Often Better

  Decaf beans can go from perfect to baked very quickly. Watch that Development Time Ratio (DTR) closely—sometimes 15–20% is plenty. Longer post-crack development can mute whatever sweetness and acidity survived the decaffeination process.

• Expect Different Flavor Profiles

  Even the best-decaffeinated coffees will usually have less acidity and less complexity than their fully-caffeinated twins. That’s not a flaw—it’s just their nature.

  Tip: Lean into body, chocolate, nutty, or spice notes. Decaf often excels here, especially medium to medium-dark roasts.

• Know Your Decaf Process

  There are several methods of decaffeination:

  • Swiss Water Process (SWP) – Clean and chemical-free, but can darken the bean surface even before roasting.

  • Mexican Mountain Water Process – Also darkens the bean surface.

  • CO₂ Process – Great for preserving origin character, more expensive.

  • Ethyl Acetate (EA or “Sugarcane” Process) – Considered a "naturally-derived" solvent method, increasingly popular for retaining fruitiness.

  Each process behaves slightly differently in the roaster, so it's important to know exactly what you're working with. Roasting decaf is all about control, patience, and respect. Treat it like a delicate vintage, and you might be surprised at how magical it can be.

  
  

Final Thoughts: Roast With Intention, Not Just Heat

Roasting isn't just about hitting time and temperature markers—it's about choosing your own coffee adventure. Want to highlight citrus and jasmine? Stay light. Want body, chocolate, and caramel? Go medium to Full City. If you prefer a strong, smoky flavor profile, opt for a French roast.

Whether you’re a home roaster with a popcorn popper or running a commercial drum roaster with six PID controllers and a playlist for every origin—what matters is understanding what’s happening inside the bean. Because once you know that, you’re not just winging it. You’re roasting with purpose.