Research question
How does particle grind size influence extraction yield (EY%), TDS, and cup flavor balance in V60 pour-over brewers while holding other parameters strictly constant?
Coffee Science / Experiment
How does grind size influence extraction?
Methodology, variables, samples, outcomes, and constraints as a reproducible experiment template.
Experiment design
Applied scientific methodology designed to isolate brewing variables and ensure cross-panel reproducibility.
Hypothesis
Declare before measuring. Finer grind distributions yield higher surface area and accelerate initial dissolution rates; particle sizes below 500 microns are predicted to trigger channeling and astringency.
Variables
Method, water chemistry, dose, time, and grind. Fixed variables: 15.0 g dose, 92°C mineralized water (110 ppm), 1:16 ratio (240 g water), bleached Hario 02 paper. Independent variable: mean grind size (450 µm to 850 µm).
Methodology
Control, replicates, and tooling. 4 replicates per grind setting (16 brew runs total). Digital TDS measurement via calibrated VST LAB III refractometer at 20°C and blind cup evaluation.
Results and limitations
Measurement log
Sample matrix, observations, anomalies, and findings. No simulated or fabricated factual claims.
| Sample | Grind (microns) | Drawdown | TDS (%) | Yield (EY%) | Sensory profile observed |
|---|---|---|---|---|---|
| M-01 (Fine) | 480 µm (Comandante 16 clicks) | 3 min 45 s | 1.52 % | 22.8 % | Heavy body, pungent bitterness, lingering astringency, dry finish.• Minor channeling observed toward final third of drawdown. |
| M-02 (Medium-fine) | 620 µm (Comandante 22 clicks) | 2 min 50 s | 1.38 % | 20.7 % | Vibrant citric acidity, balanced caramel sweetness, clean and silky finish. |
| M-03 (Medium) | 740 µm (Comandante 26 clicks) | 2 min 20 s | 1.24 % | 18.6 % | Light body, prominent green apple malic acidity, moderate sweetness, short finish. |
| M-04 (Coarse) | 860 µm (Comandante 30 clicks) | 1 min 50 s | 1.08 % | 16.2 % | Under-extracted: sour and grassy notes, watery body, notable absence of sweetness.• Excessively fast flow rate with low bed hydraulic resistance. |
Constraints and reproducibility
Findings strictly pertain to single-origin washed Arabica (Castillo, Huila) aged 14 days post-roast. Micro-channeling was inferred from drawdown duration variance and unexpected TDS drops.