SCA Defect Reference
Green Coffee Defects Guide
Complete reference for identifying and understanding coffee bean defects aligned with SCA green arabica standards.
This guide is for educational purposes. For official grading, consult a certified Q Grader.
Educational Resource
Understanding Coffee Defects
Green coffee defects are imperfections in coffee beans that can negatively impact cup quality. The Specialty Coffee Association (SCA) classifies these defects into two categories based on their severity and impact on the final cup.
Proper defect identification is essential for quality control, pricing negotiations, and ensuring consistent roasting results. This guide covers all major defect types recognized by SCA methodology.
Primary defects - Major impact on cup quality
Category 1 Defects
Category 1 defects are severe imperfections that significantly impact cup quality. A single Category 1 defect can cause noticeable off-flavors. For specialty grade coffee, zero Category 1 defects are allowed in a 350g sample.
Full Black
- What it looks like
- Beans that are completely black in color, with a shriveled and wrinkled surface. The interior is also entirely black.
- Common causes
- Over-fermentation during processing, fungal attack, or picking overripe cherries that have fallen to the ground.
- Cup impact
- Produces harsh, carbolic, and phenolic off-flavors. Even one bean can ruin an entire cup.
- Defect equivalence
- 1 bean = 1 full defect
Full Sour
- What it looks like
- Beans with a yellow to brown discoloration throughout the entire bean, often with a waxy appearance.
- Common causes
- Improper fermentation, contaminated water during processing, or delays between harvesting and processing.
- Cup impact
- Creates strong sour, vinegary, and fermented off-flavors that dominate the cup.
- Defect equivalence
- 1 bean = 1 full defect
Fungus Damage
- What it looks like
- Beans showing visible fungal growth, typically appearing as yellowish to reddish-brown spots or patches with a powdery texture.
- Common causes
- Improper drying, storage in humid conditions, or re-wetting of dried parchment.
- Cup impact
- Produces musty, moldy, and earthy off-flavors. May pose health risks due to mycotoxins.
- Defect equivalence
- 1 bean = 1 full defect
Foreign Matter
- What it looks like
- Any non-coffee material found in the sample: stones, sticks, metal, glass, or other debris.
- Common causes
- Poor sorting and processing practices, inadequate cleaning of processing equipment.
- Cup impact
- Beyond flavor impact, poses physical hazards to processing equipment and consumers.
- Defect equivalence
- 1 piece = 1 full defect
Severe Insect Damage
- What it looks like
- Beans with 3 or more visible insect bore holes, often with visible damage patterns across the bean surface.
- Common causes
- Coffee berry borer beetle (Hypothenemus hampei) infestation in the field.
- Cup impact
- Creates dirty, musty flavors and accelerates staling due to compromised bean structure.
- Defect equivalence
- 1 bean = 1 full defect
Secondary defects - Moderate impact on cup quality
Category 2 Defects
Category 2 defects have a less severe impact on cup quality but still affect the overall grade. Multiple Category 2 defects are needed to equal one full defect. For specialty grade, a maximum of 5 full defects from Category 2 are allowed in a 350g sample.
Partial Black
- What it looks like
- Beans with partial black discoloration, typically affecting less than half of the bean surface.
- Common causes
- Similar to full black but less severe. Often from partial over-fermentation or localized fungal attack.
- Cup impact
- Can contribute harsh and bitter notes, though less intense than full black.
- Defect equivalence
- 3 beans = 1 full defect
Partial Sour
- What it looks like
- Beans with partial yellow to brown discoloration, affecting part of the bean surface.
- Common causes
- Partial fermentation issues or localized contamination during wet processing.
- Cup impact
- May contribute subtle sour or fermented notes to the cup.
- Defect equivalence
- 3 beans = 1 full defect
Floater
- What it looks like
- Low-density beans that are pale, often whitish in color, with a papery texture.
- Common causes
- Drought stress, poor nutrition, or harvesting of underdeveloped cherries.
- Cup impact
- Produces grassy, straw-like flavors and roasts unevenly due to low density.
- Defect equivalence
- 5 beans = 1 full defect
Immature / Unripe
- What it looks like
- Small, often boat-shaped beans with a greenish tint and wrinkled silverskin that doesn't detach easily.
- Common causes
- Harvesting unripe cherries, often from strip-picking methods.
- Cup impact
- Creates grassy, astringent, and cereal-like flavors. Roasts lighter than mature beans.
- Defect equivalence
- 5 beans = 1 full defect
Withered
- What it looks like
- Shriveled beans with wrinkled surfaces, appearing smaller and deformed compared to normal beans.
- Common causes
- Drought stress during cherry development or irregular irrigation.
- Cup impact
- Can produce grassy, straw-like flavors and roast unevenly.
- Defect equivalence
- 5 beans = 1 full defect
Shell
- What it looks like
- Malformed beans that appear as thin, ear-shaped fragments. Only the outer portion of the bean developed.
- Common causes
- Genetic factors or stress during bean development. Common in certain varieties.
- Cup impact
- Roasts faster than whole beans, potentially scorching. Can add bitter notes.
- Defect equivalence
- 5 beans = 1 full defect
Broken / Chipped
- What it looks like
- Beans that are fragmented, cracked, or have pieces missing from mechanical damage.
- Common causes
- Rough handling during processing, hulling, or transportation.
- Cup impact
- Roasts unevenly and can contribute bitter flavors from over-roasted fragments.
- Defect equivalence
- 5 beans = 1 full defect
Hull / Husk
- What it looks like
- Dried parchment or cherry skin fragments remaining attached to or mixed with green beans.
- Common causes
- Incomplete hulling during dry processing or inadequate cleaning.
- Cup impact
- Can cause uneven roasting and add papery or woody notes.
- Defect equivalence
- 5 pieces = 1 full defect
Slight Insect Damage
- What it looks like
- Beans with 1-2 small insect bore holes, showing limited penetration.
- Common causes
- Minor coffee berry borer infestation.
- Cup impact
- Minimal flavor impact when isolated, but can accelerate staling.
- Defect equivalence
- 5 beans = 1 full defect
SCA Defect Reference
SCA Grading Standards
The Specialty Coffee Association defines strict standards for green coffee grading. These standards ensure consistency in quality evaluation across the global coffee trade.
Grading is performed on a 350-gram sample of green coffee. Beans are sorted, defects are identified and counted, and the total defect score determines the grade classification.
Specialty Grade
Zero Category 1 defects and maximum 5 full defects from Category 2 in a 350g sample. Must also score 80+ points in cupping evaluation.
Below Specialty Grade
Coffee with Category 1 defects or more than 5 full Category 2 defects does not qualify for specialty grade classification.
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