Understanding RoR (Rate of Rise) in Coffee Roasting

Kenya Coffee School Article: Understanding RoR (Rate of Rise) in Coffee Roasting

At Kenya Coffee School, roasting science is taught with a balance of theory, hands-on practice, and sensory evaluation. One of the most critical roasting concepts we train roasters to understand and control is RoR – Rate of Rise.

What is RoR (Rate of Rise)?

Rate of Rise (RoR) refers to the speed at which the coffee bean temperature increases during roasting, usually expressed in degrees per minute (°C/min or °F/min).

Importantly, RoR is not the bean temperature itself, but the rate of change of that temperature. It tells the roaster how fast heat energy is being absorbed by the beans at any given moment.

RoR is typically displayed as a curve on a roast graph and is calculated using short time intervals (commonly 30–60 seconds).

Why RoR Matters in Coffee Roasting

At Kenya Coffee School, RoR is emphasized because it provides real-time feedback and allows roasters to make informed adjustments much earlier than relying on temperature alone.

1. Flavor Development Control

A well-managed RoR supports:

• Bright, vibrant acidity
• Balanced sweetness
• Clean, well-developed flavors

Poor RoR control can lead to:

• Burnt or rubbery notes (too much heat too fast)
• Baked or flat flavors (heat drops too sharply)

2. Consistency and Repeatability

Tracking RoR allows roasters to:

• Replicate successful roast profiles
• Diagnose issues when a coffee tastes different
• Improve batch-to-batch consistency

3. Early Warning System

RoR responds instantly to changes in:

• Burner power
• Airflow
• Drum speed
• Bean density and moisture

This makes it a faster diagnostic tool than bean temperature alone.

Key RoR Concepts Taught at Kenya Coffee School

1. Flicks

Flicks are sudden upward spikes in the RoR curve, often occurring:

• Near or after first crack
• When heat is added too aggressively
• When airflow changes abruptly

Impact on flavor:

• Harsh, burnt, or smoky notes
• Reduced clarity and sweetness

2. Crashes

Crashes are sudden drops in RoR, usually caused by:

• Excessive heat reduction
• Too much airflow
• Insufficient energy going into first crack

Impact on flavor:

• Even heat application
• Proper progression through drying, Maillard, and development phases

Kenya Coffee School teaches that while smooth RoR curves are desirable, they must always serve flavor goals, not aesthetics alone.

Typical RoR Ranges (Guidelines Only)

• Below 10°C/min → Slow roast (risk of baking if unmanaged)
• 10–15°C/min → Medium, controlled development
• Above 15°C/min → Fast roast (risk of scorching if excessive)

These ranges vary depending on:

• Bean density (e.g., Kenyan high-altitude coffees)
• Moisture content
• Roaster size and design
• Desired flavor profile

How RoR is Used in Practice

At Kenya Coffee School, students learn to:

• Read RoR curves alongside bean temperature
• Adjust heat input and airflow proactively
• Shape RoR differently for:
  • Bright, acidic coffees
  • Sweet, caramel-driven profiles
  • Chocolatey or nutty expressions

RoR becomes a decision-making tool, not just a number on a screen.

RoR and Kenyan Coffee Excellence

Kenyan coffees are known for:

• High density
• Bright acidity
• Complex fruit character

Managing RoR correctly is essential to:

• Preserve acidity without harshness
• Enhance sweetness
• Maintain clarity in the cup

This is why RoR control is a core competency in Kenya Coffee School’s roasting and specialty coffee training programs.

Conclusion

Rate of Rise (RoR) is one of the most powerful indicators of roast quality. By understanding its behavior—avoiding flicks, preventing crashes, and guiding a controlled decline—roasters can unlock consistency, precision, and exceptional flavor.

At Kenya Coffee School, RoR is not just taught as a technical metric, but as a language of heat and flavor, empowering roasters to roast with confidence, intention, and mastery. ☕🔥