Roast Color Measurement
Sources: Roast Rebels (website)
Roast degree is one of the most important variables in coffee quality — it determines the balance between acidity, sweetness, body, and bitterness in the cup. Measuring roast color precisely with an instrument replaces subjective visual or tactile judgement with a numerical value on a standardized scale. This enables reproducibility across batches, communication between producers and buyers, and objective comparison of profiles. (source: Roast Rebels (website))
The Agtron Scale
The Agtron scale is the industry-standard measure of roast degree in specialty coffee. It uses near-infrared light reflectance to assign a score:
- Higher Agtron number = lighter roast (more reflectance)
- Lower Agtron number = darker roast (less reflectance)
Typical specialty coffee ranges:
| Roast style | Agtron range (whole bean) |
|---|---|
| Very light / Nordic | 70–85+ |
| Light | 60–70 |
| Medium-light | 50–60 |
| Medium | 40–50 |
| Medium-dark | 30–40 |
| Dark | Below 30 |
Exact values depend on the instrument and whether whole bean or ground is measured. Whole-bean and ground readings differ — ground is typically lower (darker) due to broken cell structure. Consistent measurement protocol (whole bean vs. ground, same grind setting) is essential for reliable comparison.
Instruments
Tonino Color Meter
Developed and manufactured by Tonino (Italian brand). Measures roast color of whole beans or ground coffee on an Agtron-equivalent scale. One of the most widely used instruments in small specialty roasteries.
- Price: €819 (as sold by Roast Rebels)
- 5/5 stars from 2 reviews (Roast Rebels listing)
- Output: standardised numerical score enabling cross-batch comparison and profile communication
- Use case: ensuring a roast profile is repeated at the same color target batch after batch; sharing roast degree information with buyers using a shared scale
Lighttells CM-200
Spectral analysis instrument from Lighttells (founded 2014, by IT engineers; specialises in coffee quality control instruments).
- Price: €1,990 (Roast Rebels list; from €2,490 regular, currently 20% off)
- Measures: roast color, color distribution (not just average), and grind particle size distribution (PSD)
- The PSD function makes it a dual-purpose instrument: roast QC and grind QC in one unit
- Use case: high-precision roastery or quality control lab
Lighttells CM-100+
Compact version of the Lighttells family. Roast color measurement only (no PSD).
- Price: ~€2,090 (Roast Rebels; originally higher)
- More portable; suitable for lab or mill use
Lighttells MD-500
Mobile quality measurement device. Specific function scope unclear from crawl data; intended for field or production use. (source: Roast Rebels (website))
Why Measurement Matters for Specialty Roasting
Visual colour assessment is highly subjective — affected by ambient lighting, bean surface texture, observer fatigue, and screen colour calibration when comparing photographs. Two roasters describing the same coffee as “light” may be working with meaningfully different roast degrees.
Numerical measurement with a calibrated instrument:
- Eliminates ambiguity in buyer–seller communication (“our Guatemala is roasted to Agtron 65”)
- Enables consistent batch replication (match last week’s reading)
- Identifies drift (same profile, same times, but Agtron reading shifted → roaster heat changed)
- Provides objective data for roast profile documentation alongside ROR curves and DTR
Relevance to Kaiserblick
Roxanne Fredericksen leads roast profile development at Kaiserblick’s roasting operation. A color meter would be a direct tool for:
- Verifying that each micro-lot reaches its target roast degree
- Providing European buyers with objective roast degree specifications
- Cross-checking profiles developed on a sample roaster against production batches
- Communicating quality standards internally as the team grows
The Tonino is the most accessible entry point (€819); the Lighttells CM-200 adds PSD capability relevant if Kaiserblick also wants to audit its grind quality in-house.