tags: [] - coffee/brewing - coffee/brewing/espresso - coffee/troubleshooting aliases: - Extraction and brewing defects - Brewing extraction defects - Extraction defects

Extraction and Brewing Defects¶

Tags: #coffee/brewing #coffee/brewing/espresso #coffee/troubleshooting Aliases: Extraction and brewing defects, Brewing extraction defects, Extraction defects Related: Coffee Defects MOC | Extraction Optimisation | Channelling | Over-extraction and Under-extraction | Water Chemistry Basics Status: 🌱 Stub

Overview¶

Extraction and brewing defects are flaws in the final brewed cup that arise from improper brewing technique, equipment calibration, or water chemistry. Unlike green bean or roast defects, extraction defects occur at the preparation stage and are typically correctable by adjusting controllable brewing variables.

Common Extraction Defects¶

Channelling: Water follows the path of least resistance through the coffee bed. If the puck has air pockets, cracks, or uneven density from poor tamping or distribution, water carves a channel through it. The result is simultaneous over-extraction along the channel and under-extraction in bypassed areas — producing a cup that is both harsh and sour. Channelling is addressed through improved distribution and tamping technique, not grind adjustment. See Channelling.

Seal breaks and edge bypassing: If the coffee puck is not properly sealed against the portafilter basket wall, water bypasses the grounds at the edges and runs down the sides. This dilutes the shot and leaves the puck centre under-extracted.

Grind size imbalance: Too fine a grind leads to over-extraction and lingering, dry bitterness; too coarse a grind allows water to flow too quickly, yielding a weak, sour, or watery cup. Grind size is the primary variable for correcting extraction level.

Water chemistry imbalance: Brewing water lacking sufficient buffer minerals produces an unpleasantly sharp cup. Water with excessive calcium or magnesium carbonate flattens acidity and creates a dull, chalky mouthfeel. See Water Chemistry Basics and Water Quality.

Key Facts¶

Extraction defects occur at the preparation stage and are correctable through variable adjustment
Channelling produces simultaneous sourness and bitterness — corrected by distribution and tamping, not grind adjustment
Grind size is the primary lever for correcting over- or under-extraction
Water chemistry defects require water treatment or mineral adjustment; grind and technique changes cannot compensate

References¶

Specialty Coffee Association — Brewing Standards

Changelog¶

Date	Change
2026-05-03	Compliance review: added frontmatter, metadata block, all required sections; removed emoji 📄 from H1; converted inline backtick tags to proper frontmatter; fixed "flavor" → "flavour", "Channeling" → "Channelling"; rewrote as encyclopedic prose; added Overview, Key Facts, Related Notes, References, Changelog, copyright

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