🅢 = Story: Why We Share What We Roast

When it comes to roasting Robusta, there isn’t a handbook, or at least not one with much depth. Most of the resources out there, from SCA trainings to online forums, are centered around Arabica.

The majority of roasting theory, curve-building, and sensory expectations were built with Arabica in mind. That leaves a huge gap when it comes to understanding Robusta – specifically, how it behaves in the drum, how it handles heat, and how it presents itself in the cup.

That’s why we’re committed to sharing what we discover. Every batch we roast is an experiment. Some things we learn by accident, and sometimes the roast confirms what we’ve seen before. A lot of times, Robusta throws us a curveball and reminds us we’re just scratching the surface.

We’re not here to claim we’ve figured it all out. We’re building this knowledge in real-time, and we want to bring you along – not just to demystify Robusta, but to contribute to a more inclusive and curious coffee conversation.

— Lan Ho, Founder of Fat Miilk

🅘 = Insight: Density Deception: What Robusta Teaches in the Drum

At Fat Miilk, we roast to order, which gives us an intimate understanding of the beans and the process. With 10+ years in the specialty coffee industry, working in quality control, sourcing, sample roasting, and now production, I’ve never been more excited to share what we’re discovering with Robusta. — Kim Nguyen, Head of Coffee Quality and Sourcing

After eight years of roasting over twenty different Arabica varieties, transitioning into Robusta roasting presented a steep and unexpected learning curve. While I had sample-roasted Robusta here and there in the coffee lab and noted my observations, full production roasting was a different beast altogether. Every time I loaded Robusta into the drum, I knew I was in for a challenge – and I welcomed it.

Lower Elevation, Lower Density

Robusta is typically grown at lower elevations, ranging from sea level up to about 1,000 meters. This lower elevation contributes to a lower-density green bean and results in a cup profile that’s often perceived as lower in acidity with a mellow, rounded sweetness.

Roasting Phases in the Drum

When I began production roasting our Honey Robusta, I approached it with a high charge temperature, typically between 420°F and 430°F. I maintained consistent heat throughout the roast until first crack. What surprised me was how well Robusta tolerated that heat. Despite its lower density, it resisted scorching even at high initial temperatures.

• Drying Phase: Lasts about 5–6 minutes, until the color begins to shift. This steady phase helps prevent scorching, particularly important for Honey-processed coffees with sticky sugars on the exterior.
  Maillard Phase: Lasts around 3 minutes. During this time, sugars slowly caramelize, setting the foundation for complexity before first crack.
  Development Phase: Usually runs 2.5–3 minutes, depending on the desired roast profile, before dropping the coffee into the cooling tray.

Low-Density Bean, High-Density Behavior

One of the most fascinating things about Robusta is its unique thermal behavior. While it roasts like a lower-density coffee for most of the process, its cellular structure allows it to handle heat more like a high-density Arabica – similar to a Kenyan SL28.

Just when I thought I couldn’t push the heat further, Robusta proved me wrong. It sustained the Maillard phase with consistency, no air pockets, no uneven discoloration, no tipping. (More on tipping in a future newsletter.)

Robusta, as a member of the Canephora species, continues to challenge conventions. It’s a durable, dynamic, and incredibly likable varietal. The more I roast it, the more I realize how much it has to offer. There’s still so much to learn and I look forward to sharing my findings with others. 

🅟 = Pulse: The Robusta Resurgence

It’s no longer just the big players quietly blending Robusta into their espresso lines. Roasters of all sizes are beginning to pay attention. From micro-roasteries experimenting with single-origin Robusta for the first time to large-scale operations seeking climate-resilient options, Robusta is making its way back into the spotlight – not as a filler, but as a feature.

A few key truths drive this resurgence: Robusta is durable, bold, and packs a caffeinated punch. When handled with care, it holds incredible flavor complexity that challenges the old narratives. Roasters are waking up to the potential of a bean that can perform under heat, thrive at lower elevations, and still hold its own in the cup.

The industry is beginning to realize that Robusta isn’t just “the other bean.” It’s a varietal worth roasting with intention and exploring with curiosity. At Fat Miilk, we’ve seen firsthand what happens when people taste Robusta roasted with care. Curiosity turns into surprise, and surprise turns into obsession.

The Robusta Revolution® is here. Are you paying attention?