tags: [] - coffee/brewing - coffee/science aliases: - Coffee extraction basics - How coffee extraction works - Extraction science basics

Extraction Fundamentals¶

Tags: #coffee/brewing #coffee/science Aliases: Coffee extraction basics, How coffee extraction works, Extraction science basics Related: Coffee Extraction Fundamentals MOC | Extraction Yield | Grind Adjustment | Water Chemistry Basics | Espresso Basics Status: ✅ Complete

Overview¶

Extraction is the process by which brewing water dissolves soluble compounds from ground coffee and carries them into the cup. Coffee beans contain both soluble compounds (which dissolve in water) and insoluble matter (cell walls, fibre) that remains behind in the grounds. Understanding what extracts, in what order, and at what rate provides the conceptual foundation for all recipe decisions and dialling practice.

What Extraction Is¶

Roasted coffee is approximately 28–30% soluble by mass. The insoluble remainder — cellulose, fibre, structural proteins — stays in the spent grounds regardless of brew method or duration. Coffee contains:

Sweet compounds: Sucrose residues, caramelisation products, Maillard products — contribute pleasant sweetness and body
Acidic compounds: Organic acids (malic, citric, chlorogenic) — pleasant in balance; harsh in excess
Bitter compounds: Caffeine (clean bitter), degraded chlorogenic acids, melanoidins — acceptable in small amounts, unpleasant in excess
Body compounds: High-molecular-weight melanoidins and lipids (when not filtered) — contribute mouthfeel and texture

The Extraction Sequence¶

Compounds do not extract at the same rate. They dissolve in a roughly predictable sequence:

Acids extract first — bright, fruity, high-solubility organic acids dissolve quickly; early in extraction these dominate the cup
Sugars and sweetness extract in the middle phase — balanced, sweet-fruit, and caramel notes
Bitter and heavy compounds extract last — lower solubility; require more time or heat to dissolve

This sequence explains why under-extracted coffee tastes sour (acids dominate, sweetness absent) and over-extracted coffee tastes bitter and harsh (too many late-extracting bitter compounds). The goal is to cut extraction where acids, sugars, and body are balanced and bitter compounds are present only in the background.

Extraction Yield¶

Extraction yield (EY) is the percentage of the dry coffee dose that has dissolved into the liquid:

EY (%) = (Brewed weight × TDS) ÷ Dry dose weight × 100

SCA target range: 18–22% extraction yield for most brew methods.

Extraction yield	Character
Below 18%	Under-extracted: sour, sharp, thin
18–22%	Target zone: balanced, sweet, complex
Above 22%	Over-extracted: bitter, harsh, drying

Variables That Control Extraction¶

Six variables directly control how much extraction occurs:

Variable	Effect when increased	Effect when decreased
Grind fineness	Higher extraction	Lower extraction
Brew temperature	Higher extraction	Lower extraction
Contact time	Higher extraction	Lower extraction
Dose (relative to water)	Lower extraction (more coffee per volume)	Higher extraction
Water mineral content	Variable — affects solubility of specific compounds	Variable
Pressure (espresso)	Increased at optimal range	Under-pressure = under-extraction

Grind size is the primary lever in espresso because it controls how quickly water moves through the puck — simultaneously affecting contact time and resistance.

Concentration vs. Extraction Yield¶

These are distinct metrics that are frequently confused:

Concentration (TDS): How much dissolved material is in the liquid — the strength of the cup. A ristretto has higher TDS than a lungo.

Extraction yield: What percentage of the coffee's mass has dissolved. A ristretto and lungo can reach similar extraction yields despite very different concentrations — the ristretto achieves it in less water, the lungo in more.

The SCA Brewing Control Chart plots concentration against extraction yield, with a target "ideal" zone. This framework underlies specialty coffee recipe development.

Filter vs. Espresso Extraction¶

The same principles apply to both methods, but conditions differ significantly:

Factor	Espresso	Filter (pour-over)
Pressure	~9 bar	Gravity (~0.001 bar)
Grind size	Very fine	Medium to coarse
Contact time	25–35 seconds	2–4 minutes
Brew ratio	1:2 (typical)	1:15–1:17
TDS target	~8–10%	~1.2–1.5%
Extraction yield target	18–22%	18–22%

Both methods target the same extraction yield range but achieve it through fundamentally different mechanisms.

Key Facts¶

Coffee is ~28–30% soluble by mass; the rest (cellulose, fibre) never dissolves regardless of brew parameters
Extraction sequence: acids first → sweetness/sugars mid → bitter/harsh compounds last
Under-extracted: sour (too many acids, not enough sweetness); over-extracted: bitter/harsh (too many late compounds)
SCA target extraction yield: 18–22% for most methods
Grind size is the primary extraction control in espresso; contact time is primary in most filter methods

References¶

Changelog¶

Date Change

2026-05-03 Compliance review: added frontmatter, metadata block, all required sections; removed _Part of 05_PUBLISHING/Homepage/Coffeepedia... footer; fixed ../Grind Adjustment → [Grind Adjustment](../coffee-equipment/grind-adjustment.md), ../Water Chemistry Basics → [Water Chemistry Basics](../coffee-brewing/water-chemistry-basics.md); replaced ## Related Topics inline link group with ## Related Notes bullets; fixed "weak flavors" → "weak flavours"; fixed table alignment; added copyright

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