The Physics Of Filter Coffee Pdf May 2026

[ \textExtraction Yield (%) = \frac\textBrewed coffee solids (g)\textDry coffee grounds (g) \times 100 ]

Coffee extraction is a mass transfer process where solids move from the coffee cell wall matrix into the water solvent.

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The movement of solutes from the coffee particle to the water is governed by Fick’s First Law (steady-state diffusion):

$$J = -D \fracd\phidx$$

Key Physics Concept: Water wants to move from an area of high solute concentration (inside the coffee particle) to low concentration (in the brew water).

| Compound | Solubility in water | Extraction timing | |----------------|---------------------|-------------------| | Citric/Malic acids | Very high | First 30 seconds | | Sugars (sucrose) | High | 30–120 seconds | | Caffeine | Medium | Throughout | | Chlorogenic acids | Medium-high | After 90 seconds | | Tannins/Bitters | Low | After 3 minutes | The Physics Of Filter Coffee Pdf

Key insight: A longer brew does not make coffee “stronger” in a good way—it adds bitter compounds.