Self-study lesson
Lesson 2.3: Defects 101
The learning loop
- Notice: smell or taste slowly before naming.
- Name: write simple words first; refine later.
- Compare: check another cup, stage, or reference.
- Record: write what changed and what stayed stable.
- Repeat: make one small improvement next session.
A defect is a repeatable negative clue, not an insult to the coffee or producer. It may come from green coffee, processing, storage, roasting, grinding, water, or cupping setup.
Defect training protects honesty. It also prevents beginners from blaming the wrong part of the chain too quickly.
A moldy note may point to storage or processing, while rubbery smoke may point to roast or contamination. Confirm before concluding.
From the KoffyKraft notes
Not every roast results in a perfect cup. Recognizing defects is a vital cupping skill. In this lesson, you'll learn to detect and describe common sensory defects caused by poor processing, storage, or roasting. This is not about blaming - it's about clarity and communication.
Objectives
- Identify and describe common sensory defects
- Understand how roast, origin, and processing affect defects
- Differentiate between origin-specific traits and flaws
- Build confidence in calling out defects clearly and respectfully
Tools Needed
- 3 coffees: 1 known clean cup, 1 with past defect (if available), 1 unknown or experimental roast
- Cupping tools (8.25g x 3 cups, 150ml water, timer, spoon)
- Notebook or defect form (blank or scored)
Cupping Protocol - Defect Identification
- Prepare 3 cups using standard protocol.
- Smell and slurp each sample. Focus on unfamiliar, unpleasant, or unbalanced traits.
- Use the Defect Reference Table to match what you taste.
- Ask: Is this flavor natural to the origin or a result of poor handling?
- Mark intensity: low, medium, or strong.
- Identify at which stage the defect appears (aroma, taste, aftertaste).
- Score clarity and cleanliness alongside defect recognition.
Defect Reference Table (Basic)
| Defect Type | Cause | When Detected | Descriptor Examples |
|---|---|---|---|
| Quaker (Pale Bean) | Underdeveloped or dead bean | Dry/wet aroma, taste | Papery, stale, peanut shell |
| Sour | Under-roasted or poor fermentation | Taste | Sharp, biting, green fruit |
| Phenolic | Overfermented or tainted | Aroma, taste | Medicinal, rubbery, smoky |
| Musty/Moldy | Improper storage/moisture | Aroma, aftertaste | Basement, wet wood |
| Baked | Flat roast curve | Taste, aftertaste | Stale bread, no acidity |
| Scorched/Tipped | Too hot too fast | Dry aroma, taste | Burnt, ash, smoky |
Self-Check
- Could you match any cups to a known defect type?
- Were you able to describe when the defect showed up (aroma, taste, etc.)?
- Were you hesitant to call it a defect? Why or why not?
Before You Move On
Practice identifying defects in multiple sessions. Don't rush to label something bad - focus on repeatable description and detection. When you can name 3-4 common defects confidently, move to Lesson 2.4.
Practice this way
- Prepare the cups as described in the original notes.
- Before tasting, write the question for this session in one sentence.
- Taste in stages: hot, warm, and cooler. Do not rush to a final answer.
- Use plain language first. Add professional terms only when they help.
- Review your notes after ten minutes and underline what feels repeatable.
Common beginner mistakes
- Calling a defect from one spoonful.
- Using harsh words without evidence.
- Forgetting to check water, cups, grinder, and roast date.
Self-check with answers
1. What is the main skill in this lesson?
Answer: Defect notes should be repeatable across sips and preferably across cups.
2. What should you do if your note feels uncertain?
Answer: Always check setup before blaming coffee.
3. What makes the observation more reliable?
Answer: Useful defect words include moldy, phenolic, medicinal, rubbery, smoky, baggy, sour, fermenty, earthy, and stale.
Notebook entry
| Prompt | Your note |
|---|---|
| Session question | |
| First impression | |
| Most repeatable observation | |
| One uncertainty | |
| Next session change |
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