tags: [] - coffee/roasting - coffee/roasting/profile aliases: - RoR analysis - Analysing Rate of Rise

Rate of Rise Analysis¶

Tags: #coffee/roasting #coffee/roasting/profile Aliases: RoR analysis, Analysing Rate of Rise Related: Roasting MOC | Rate of Rise | Development Time Ratio | Artisan Software | Cropster Status: ✅ Complete

Overview¶

Rate of Rise (RoR) analysis is the practice of examining the RoR curve — the derivative of the bean temperature (BT) curve over time — to assess, diagnose, and refine a roast profile. While the absolute temperature curve shows where the roast is, the RoR curve shows how fast it is getting there, and the shape of this curve is a primary indicator of profile quality. Scott Rao's work establishing the declining RoR model as a quality reference has made RoR analysis a central skill in specialty roasting; understanding how to read the RoR curve is fundamental to diagnosing baked, underdeveloped, crashed, or well-executed roasts.

Reading the RoR Curve¶

The RoR curve is typically displayed in profile software (Artisan, Cropster) in degrees Celsius per minute (°C/min) on a secondary y-axis overlaid on the BT curve. Key features:

Initial RoR after charge: The RoR begins very high after green coffee is charged into the hot drum — sometimes 20–30°C/min or more — then falls rapidly as the cold bean mass absorbs heat and the drum cools. This initial spike is not meaningful for profile analysis.

Turning point: The BT reaches its minimum (the turning point) when the RoR passes through zero. After the turning point, RoR is positive and the bean temperature rises continuously.

Post-turning-point RoR peak: In a well-managed declining RoR profile, the RoR peaks relatively early (often in the first 1–3 minutes after turning point) and then declines continuously through the rest of the roast.

Browning phase RoR: A smooth, declining RoR through the 155–190°C zone indicates controlled energy delivery. A flat or rising RoR in this zone indicates too much energy and potential scorching or rushed browning.

First crack RoR: At first crack, the exothermic reaction temporarily reduces the apparent RoR (the bean releases heat, reducing the temperature difference between bean and heat source). A well-managed profile shows a brief, controlled RoR dip at first crack without crashing to zero or below.

Development phase RoR: Post-first-crack, a controlled declining RoR (typically 3–8°C/min depending on roaster and target) is the standard for specialty profiles. The RoR should continue declining gently to drop.

The Declining RoR Model¶

The declining RoR model — where the RoR consistently decreases from its post-turning-point peak to drop without plateauing or rising — is the most widely adopted quality framework in specialty roasting. Its rationale:

A declining RoR means the bean is absorbing heat at a decreasing rate; the bean is "catching up" to its environment rather than being driven harder as temperature rises
Flat or rising RoR indicates the roaster is applying increasing energy relative to bean temperature, which risks development imbalance (scorching at high temps, baking at lower temps)
The crash-and-flick pattern (RoR falls sharply near first crack then rises) is a particularly notable defect in RoR shape, associated with reactive overcorrection and uneven development

Diagnosing Problems from RoR¶

RoR pattern	Diagnosis	Cup symptom
Rising RoR through browning	Excessive heat; runaway heating	Possible scorching; harsh bitterness
Flat RoR through browning	Insufficient heat; baking risk	Flat, bread-like, no sweetness
Sharp RoR crash pre-first-crack	Excessive heat reduction anticipating crack	Stalled development; underdevelopment
Flick (rise) after first crack	Reactive overcorrection; crash-and-flick	Uneven development; sour-baked combination
RoR approaching zero in development	Prolonged low-temperature soak	Baked character; flat, dull cup
Smooth declining RoR throughout	Well-managed declining profile	Clean development; balance of origin and roast

Comparing RoR Curves Across Batches¶

RoR analysis is most powerful when comparing curves across multiple batches: - Overlaying RoR curves for batches of the same green coffee allows identification of batch-to-batch inconsistency - Environmental changes (ambient temperature, humidity), batch weight variation, or equipment wear all shift the RoR curve; analysis identifies these before they become chronic quality problems - Profile logging software (Artisan, Cropster) facilitates automatic RoR comparison across sessions

Limitations of RoR Analysis¶

RoR curves are sensitive to probe placement and response time; noisy or slow probes produce jagged or delayed RoR readings
RoR is a derivative — small fluctuations in the BT reading are amplified in the RoR; smoothing in software reduces noise but can obscure real events
RoR analysis must be contextualised with the absolute temperature curve, DTR, and cup result — RoR shape alone does not fully determine cup quality

Key Facts¶

RoR analysis reads the derivative of the BT curve to assess how rapidly and evenly heat is being delivered to the bean mass
The declining RoR model (continuously decreasing from post-turning-point peak to drop) is the dominant quality framework in specialty roasting
Key diagnostic patterns: rising RoR (excess heat), flat RoR (baking), crash-and-flick (reactive overcorrection), RoR approaching zero in development (baking)
Most valuable when comparing across batches; overlaying curves identifies systematic variation from environmental or equipment factors
RoR curves are noisy — probe quality, smoothing settings, and data logging rate all affect readability

References¶

Changelog¶

Date	Change
2026-04-27	Note created

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