tags: [] - coffee/roasting - coffee/tasting aliases: - Roast defect flavour fault table - Roast defects and flavour faults - Roasting defect reference

Roast Defect → Flavour Fault Reference Table¶

Tags: #coffee/roasting #coffee/tasting Aliases: Roast defect flavour fault table, Roast defects and flavour faults, Roasting defect reference Related: Roasting MOC | Roast Profile | Coffee Defects | Cupping | First & Second Crack Status: ✅ Complete

Overview¶

This reference table maps common roasting defects to their characteristic flavour faults as detected during cupping or tasting. Roasting defects arise from errors in heat application, timing, or process control during the drum roast. Identifying the flavour fault allows the roaster to diagnose the likely cause and correct the roast profile. This table complements the more detailed articles on roast profiles and sensory evaluation.

Roast Defect → Flavour Fault Table¶

Roast Defect	Cause	Flavour Fault(s)	Cup Descriptor(s)
Underdevelopment	Roast dropped too early; insufficient time post-first-crack	Raw, starchy, grassy flavours; lack of sweetness	Green, grassy, hay, bread dough, papery
Overdevelopment	Extended time post-first-crack; high DTR	Baked, flat, hollow flavour; loss of brightness	Bready, caramelised, flat, dull acidity
Scorching	Excessive charge temperature or direct drum heat; surface burns before core develops	Harsh, acrid, smoky notes	Smoky, burnt, acrid, phenolic
Tipping	Bean tips or edges burned from drum contact or hot spots	Localised bitterness; sharp, harsh finish	Bitter, ashy, harsh
Baking	Temperature stalled or dropped during Maillard phase; insufficient RoR	Sweet but flat; no brightness; hollow body	Baked, bread-crust, caramel without acidity
Roast crash	Rate of Rise (RoR) drops sharply to zero or negative near first crack	Astringent, papery, flat; poor sweetness development	Papery, astringent, flat, medicinal
Flick	RoR rises sharply near drop; excess heat applied late	Harsh surface development; uneven roast	Bitter, smoky on finish; uneven cup
Quaker contamination	Unripe green beans roast pale; not a roast process defect but detected post-roast	Peanutty, bland, hollow notes on unripe beans	Peanut, straw, flat
Excessive dark roast	Extended development past second crack	Carbon notes; complete destruction of origin character	Bitter, smoky, ashy, burnt rubber
Uneven roast	Poor air flow; uneven drum; incorrect batch size	Inconsistent cup; some beans under-, some overdeveloped	Mixed; bright then flat; uneven sweetness

Key Flavour Fault Descriptions¶

Flavour Fault	Likely Defect Category	Roast Phase Implicated
Grassy / green / hay	Underdevelopment	Drying or early Maillard
Papery / cardboard	Underdevelopment or RoR crash	Drying or Maillard phase stall
Baked / bread crust	Baking defect	Maillard phase (stalled RoR)
Flat / hollow sweetness	Overdevelopment or baking	Post-first-crack or extended development
Smoky / acrid	Scorching or excessive dark roast	Charge or post-second-crack
Bitter / harsh	Tipping, scorching, or excessive dark roast	High-heat contact; post-second-crack
Astringent	RoR crash; underdevelopment	Maillard stall or early drop
Peanut / straw	Quaker (unripe bean)	Pre-roast green bean defect

[!NOTE] Many flavour faults have multiple possible causes. Diagnosis requires evaluating the full roast curve — charge temperature, Maillard phase RoR, first crack timing, DTR, and drop temperature — alongside the cupping result. No single flavour fault is diagnostic of one cause in isolation.

[!TIP] The most reliable diagnostic workflow is to cup the coffee alongside the roast log simultaneously. If scorching is suspected, inspect beans visually for surface discolouration or tipping before cupping.

Corrective Actions by Defect¶

Defect	Correction
Underdevelopment	Extend development time; lower charge temp to allow longer Maillard phase; increase DTR
Overdevelopment	Drop earlier; reduce DTR; lower end-temperature target
Scorching	Reduce charge temperature; reduce drum heat in the first 2 minutes
Baking	Increase heat input during Maillard phase; maintain positive RoR through to first crack
RoR crash	Identify cause of RoR drop (usually excess charge weight or heat withdrawal); increase burner input earlier
Tipping	Reduce charge temperature; ensure even bean movement in drum; check batch size

Key Facts¶

Underdevelopment produces grassy, papery, raw flavour faults; the cup lacks sweetness and body
Overdevelopment and baking both produce flat, hollow cups — but baking results from stalled RoR, not simply extended time
Scorching and tipping are high-heat defects that produce smoky, acrid, bitter notes
A RoR crash near first crack is one of the most common causes of papery, astringent cups
Quakers (unripe beans) are a green bean defect, not a roast defect — but they manifest as flavour faults in the cup
Visual inspection of roasted beans alongside cupping is the fastest diagnostic workflow

References¶

Changelog¶

Date	Change
2026-04-29	Note created

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