Defect libraries and references

Why Defect Libraries Matter

• Coffee defects can appear at any stage: green storage, roasting, or brewing.
• Without reference training, cuppers may misidentify or overlook critical defects.
• Libraries create a shared framework for consistent identification and scoring.

Common Defects to Catalog

1. Green Coffee Defects:

• Phenolic (ferment, chemical taints)
• Musty / moldy
• Earthy
• Insect damage
• Aged/stale

2. Roast Defects:

• Scorched
• Baked
• Underdeveloped (grassy, cereal)
• Tipped

3. Brew Defects:

• Channeling (sharp sourness, imbalance)
• Over-extraction (bitterness, dryness)
• Under-extraction (sour, thin)

Building a Defect Library

• Physical Samples:
• Collect and store defective green beans (e.g., moldy, insect-damaged).
• Roast defect batches deliberately for training.
• Reference Kits:
• Commercial sensory kits (e.g., Le Nez du Café) provide standardized aroma references.
• Documentation:
• Create detailed notes, sensory descriptors, and scoring ranges.
• Use photos and recorded cupping data for training guides.

Training with Defect Libraries

• Run calibration cuppings including both clean and defect-present samples.
• Train tasters to identify threshold levels where defects become noticeable.
• Use blind and triangulation tests to confirm reliability.

Practical Tips

• Keep libraries updated with fresh samples—old references lose accuracy.
• Cross-train with multiple cuppers to avoid individual bias.
• Record defect frequency in QC logs to monitor supplier or roast trends.

Summary

Defect libraries and references are essential sensory tools for coffee QC. By cataloging common defects, using reference kits, and training with structured cuppings, teams develop sharper sensory skills and ensure more consistent, reliable quality assessment.

• Tags:
• Green Coffee
• Practical Tips
• Ensure Consistent
• Extraction Bitterness
• Qc Logs
• Matter Coffee
• Green Beans
• Roasting Brewing
• Extraction Sour
• Insect Damaged
• Defects Phenolic
• Insect Damage