A Visual Defect Identification Chart is extremely useful in training farmers, baristas, mill operators, and cuppers because it allows students to quickly connect bean appearance with cup defects. Below is a Kenya Coffee School training chart structure that can be printed as a poster for classrooms, cupping labs, and farmer trainings under Barista Mtaani.
Kenya Coffee School
Coffee Green Bean Defect Identification Chart (Training Reference)
1. Quakers (Immature Beans)
Visual Signs
- Pale yellow after roasting
- Lighter than other roasted beans
- Often smaller and less dense
Cause
- Harvesting unripe green cherries
Cup Impact
- Papery
- Peanut-like
- Dry finish
- Weak body
2. Coffee Berry Borer Damage
Visual Signs
- Small pinholes in beans
- Internal tunnels
- Powder-like residue
Cause
- Coffee Berry Borer insect (Hypothenemus hampei)
Cup Impact
- Dirty cup
- Woody taste
- Flat flavor
3. Moldy Coffee Beans
Visual Signs
- White or green fungal patches
- Discoloration
- Powdery appearance
Cause
- Poor drying
- High storage humidity
Cup Impact
- Musty
- Earthy
- Medicinal taste
4. Black Beans
Visual Signs
- Dark black color
- Hard and brittle
Cause
- Over-fermentation
- Rotten cherries
Cup Impact
- Bitter
- Phenolic
- Harsh
5. Sour Beans
Visual Signs
- Yellowish brown color
- Slightly translucent
Cause
- Over fermentation
Cup Impact
- Vinegar
- Sour milk
- Sharp acidity
6. Broken Beans
Visual Signs
- Broken fragments
- Split beans
Cause
- Mechanical damage during milling
Cup Impact
- Uneven roasting
- Burnt notes
7. Shell Beans
Visual Signs
- Thin shell-like bean
- Curved and hollow
Cause
- Genetic mutation
- Poor pollination
Cup Impact
- Inconsistent roasting
8. Floaters
Visual Signs
- Float in water during washing
- Low density beans
Cause
- Immature cherries
- Insect damage
Cup Impact
- Flat cup
- Weak body
Kenya Coffee School Training Exercise
Exercise 1: Green Bean Sorting
Students separate beans into:
- Quakers
- Black beans
- Broken beans
- Insect damage
- Shell beans
Exercise 2: Defect-to-Cup Connection
Students cup samples containing:
- Quakers
- Moldy beans
- Sour beans
Then record aroma, acidity, body, and aftertaste.
Core Teaching Message
Kenya Coffee School & Barista Mtaani
Every defect tells a story about what happened at the farm, factory, mill, or roastery.
A trained coffee professional must be able to see the defect, smell the defect, and taste the defect.
That is how we protect the integrity of Kenyan specialty coffee.