Editorial preview · publisher details and technical verification are still being completed. Read the status
Cup & Ratio
Menu

Extraction Mass-Balance Calculator & 16-Defect Sensory Compass

Coffee Extraction Yield (EY%), TDS & Flavor Defect Diagnostic Compass

Every cup of brewed coffee sits at a specific coordinate on a two-dimensional plane defined by Beverage Strength (TDS%, Total Dissolved Solids—the mass fraction of dissolved coffee solubles in the liquid cup) and Extraction Yield (EY%—the percentage of dry roasted coffee bean mass dissolved into the brew, where maximum soluble mass in Coffea arabica is roughly 30%–32% by weight and the remaining 68%–70% is insoluble cellulose and lignin fiber). Because drip percolation and full immersion obey different mass-conservation equations—and because micro-channeling can create simultaneous localized under- and over-extraction—use the interactive calculator and complete 16-defect static HTML reference table below to estimate extraction yield under the stated assumptions and explore possible explanations for common sensory observations.

Interactive Percolation vs. Immersion Extraction Yield (EY%), LRR & Bypass Calculator

1. Brew Mode, Coffee Dose, Water Mass & Refractometer TDS%
Percolation uses Beverage Mass; Immersion uses Total Water Mass.
Weight of dry roasted coffee beans before grinding.
Water poured onto the coffee bed (excluding post-brew bypass).
Liquid weight in carafe/cup after drawdown (Percolation).
Filter target: 1.25%–1.45%; Espresso target: 8.5%–11.5%.
Pure water added directly to carafe/cup after brewing.
2. Filter Sensory Defect Compass Below

Calculated Extraction Yield (EY%), Retained Liquid Ratio & Final Strength

20.10%
Standard Extraction Yield (EY%)
20.28%
Interstitial-Corrected Exact EY%
1.38%
Final Cup TDS% (After Bypass)
3.02 g
Dissolved Coffee Solubles Mass
2.10 g/g
Retained Liquid Ratio (LRR)
1 : 16.7 (1 : 14.6 out)
Water-to-Dose / Yield Ratio
  • Balanced SCA Extraction Window (19.0%–22.0% EY): At 20.10% EY and 1.38% TDS, sweetness, organic acidity, and tactile body are in equilibrium.

1. Complete 16-Defect Coffee Extraction & Flavor Diagnostic Compass (Static HTML Reference)

The static HTML reference table below maps 16 common sensory defects in pour-over, immersion, and espresso brewing to their underlying coordinate on the Extraction Yield (EY%) × Beverage Strength (TDS%) plane, the physical or chemical mass-transfer mechanism responsible, and the exact corrective adjustment to grind microns, brew water temperature, contact ratio, or water alkalinity.

# & Sensory DefectCup Taste & Tactile SymptomsTypical EY% & TDS% CoordinatePrimary Mass-Transfer / Chemical MechanismExact Dial-In Adjustment Protocol
1. Sharp Sour & Salty BitePiercing citrus/malic sourness on the front of the tongue with a saline, mineral-salty finish and zero lingering sweetness.EY < 17.5%
TDS 1.15%–1.35% *(Filter)* or < 17% EY *(Espresso)*		Severe under-extraction: fast-dissolving inorganic salts (`K⁺`, `Na⁺`) and low-molecular-weight organic acids (citric, malic, quinic) strip off particle surfaces before slower Maillard disaccharides and caramel melanoidins diffuse out of internal bean pores.Grind 40–70 µm finer (filter) or 10–25 µm finer (espresso) to increase surface area; raise water temperature by +2°C to +4°C (`94°C–96°C`); extend brew ratio from `1:15` to `1:16.5` or `1:17`.
2. Vegetal, Grassy, or Peanut NoteRaw green pea, hay, roasted peanut skin, or cereal grain flavor with thin, watery mouthfeel.EY 15.0%–17.5%
*(Or underdeveloped roast core)*		Either severe hydraulic under-extraction or an underdeveloped roast core where Strecker degradation and Maillard caramelization did not complete inside the bean center (`RoR` crash during roasting).First push extraction higher using boiling `97°C–99°C` water and a finer grind; if the grassy/peanut note persists at `20.5% EY`, rest the beans or verify roast development time ratio.
3. Weak, Watery & Sour (Under-Extracted + Low TDS)Translucent, tea-like body with sharp, unbuffered sourness and empty mid-palate.EY < 18.0%
TDS < 1.15%		Lower-left quadrant of the SCA Brewing Control Chart: coarse grind or rapid channeling combined with an overly wide water-to-coffee ratio (`> 1:18`) yields both low extraction and high dilution.Grind significantly finer (`-60 to -90 µm`) AND tighten your brew ratio from `1:18` back to `1:15.5–1:16.0` (e.g., increase dose from `14 g` to `16 g` per `250 g` water).
4. Heavy, Cloying Sour Ristretto (Under-Extracted + High TDS)Syrupy,viscous texture that coats the mouth in intense battery-acid sourness and salty sharpness.EY 15.5%–17.8%
TDS 11.5%–14.5% *(Espresso)* or > 1.55% *(Filter)*		Upper-left quadrant: using a tight solvent ratio (`1:1.2–1:1.5` ristretto or `1:12` filter) saturates the small water volume with early-eluting acids, collapsing the concentration gradient (`C_s - C_b`) needed to extract sweet sugars.Lengthen the brew ratio (`1:2.2 to 1:2.5` for light-roast espresso, or `1:16–1:17` for filter) so fresh solvent continues extracting Maillard sweetness, or use post-brew bypass dilution.
5. Tannic Astringency & Dry TonguePuckering, sandpaper-like dryness on the tongue and inner cheeks (like over-steeped black tea or unripe persimmon) that lingers for minutes.Apparent EY 18.5%–20.5% *(Masked by localized channeling)*Localized hydraulic channeling: water jets repeatedly through low-resistance fissures in the coffee bed, stripping high-molecular-weight polyphenolic tannins and chlorogenic acid oligomers from channel walls (locally `> 27% EY`) while bypassing the dense surrounding bed.Do not simply grind finer (which worsens bed clogging and channeling!). Use WDT (`0.3–0.4 mm` needles) for espresso, pour gentler concentric circles (`4–6 g/s`), avoid high-wall pouring that disturbs the bed, and coarsen grind slightly (`+30 µm`) if drawdown stalls.
6. Sour-Bitter Confusion (Simultaneous Sour + Harsh Finish)Cup attacks with sharp front-palate sourness yet finishes with a harsh, dry, bitter back-palate bite.Apparent EY 18.0%–19.8% *(Wide bimodal particle span)*Classic bimodal defect: a wide particle distribution (`sub-100 µm` fines mixed with `900+ µm` boulders) or uneven puck preparation causes fines to over-extract past `26% EY` (bitter/astringent) while boulders center-extract at `14% EY` (sour).Upgrade grinder alignment or sift/slow-feed beans (`30°–45°` tilted grinder feeding reduces fines by `15%–25%`); perform a 3-cup sensory triangulation test (Guide #12) to isolate the dominant fault.
7. Hollow / Empty Mid-PalateBright initial aroma followed by a sudden gap in the middle of the sip and a dry woody tail.EY 18.0%–19.5%
TDS 1.20%–1.35%		High-bypass side-wall percolation: water poured directly onto the paper filter ribs runs down between the paper and the brewer wall into the carafe without passing through the coffee bed (`unintended bypass`).Keep all pour streams within the central `60%–70%` diameter of the slurry; perform a gentle `2-second` Rao spin after the final pour to level the bed and prevent side-wall craters.
8. Bitter, Ashy & Roasty (Uniform Over-Extraction)Heavy, dark-chocolate-to-charcoal bitterness, roasted wood, and lingering medicinal aftertaste.EY > 22.8% *(Light/Med)* or EY > 20.5% *(Dark Roast)*Excessive mass transfer late in the brew extracts slow-diffusing phenylindanes (formed from caffeic acid breakdown in darker roasts), trigonelline degradation products, and bitter lignocellulose hydrolysis compounds.Coarsen grind by 50–80 µm (filter) or 15–30 µm (espresso); lower brew water temperature to 88°C–91°C (190°F–196°F) for medium-dark roasts; shorten contact ratio from `1:17` to `1:15`.
9. Muddy, Silty & Sludgy CupCloudy cup with gritty sediment at the bottom, muted floral clarity, and heavy lingering bitterness.EY 21.0%–23.5%
High suspended solids		Excessive sub-100 µm fines passing through a coarse metal mesh filter or low-density paper filter, continuing slow solid-liquid extraction inside the hot carafe even after brewing finishes.Switch from metal mesh to a tight-pore bleached cellulose filter (e.g., Cafec Abaca / Hario tabbed; see Guide #9) or decant French press through a paper filter after a 4-minute settling crust break.
10. Choked / Stalled Drawdown (> 4:30 V60 or > 45s Shot)Drip bed turns into a stagnant mud puddle; brew takes 5+ minutes and tastes woody, astringent, and flat.EY > 22.0% + Severe ChannelingDarcy’s Law permeability collapse: excessive agitation or dense Ethiopian/Kenyan fines migrate to the filter paper interface, forming an impermeable cake (`filter blinding`) that drops hydraulic conductivity `k` by 80%.Coarsen grind by 60–100 µm; reduce pour count from 5 pulses to a bloom + 2 gentle pours; avoid aggressive swirling late in the drawdown.
11. Flat, Chalky, Lifeless Acidity (High Bicarbonate Mute)High-grown washed coffee tastes dull, soapy, chalky, or cardboard-flat with zero sparkling fruit notes despite `20.5% EY`.Normal EY 19.5%–21.5%
Water KH > 85 ppm as CaCO3		Carbonate alkalinity buffering: high bicarbonate (`HCO3⁻`) concentration in hard tap water neutralizes free hydrogen ions (`H⁺ + HCO3⁻ → H2CO3 → CO2 + H2O`), converting bright citric and malic acids into flat conjugate salts.Lower water Carbonate Alkalinity (`KH`) to 30–45 ppm as CaCO₃ for filter coffee (`45–65 ppm` for espresso) using our Water GH/KH Matrix.
12. Needle-Sharp, Thin Vinegar Acidity (Zero-Buffer Water)Harsh, unbuffered, one-dimensional sourness and thin body even when `EY%` is pushed to `21.5%`.Normal EY 20.0%–21.8%
Water KH < 10 ppm, GH < 20 ppm		Brewing with pure distilled, zero-TDS pitcher, or un-remineralized reverse-osmosis (`RO`) water: without `Mg²⁺`/`Ca²⁺` cations to extract sweet aromatics and without `25–40 ppm` `HCO3⁻` to buffer peak proton spikes, organic acids taste raw and aggressive.Remineralize RO/distilled water to 60–90 ppm GH (`MgSO4·7H2O`) and 30–40 ppm KH (`NaHCO3` or `KHCO3`); see Guide #3.
13. Salty-Baking-Soda Off-TasteSavory, saline, mineral-water slickness on the sides of the tongue.Water Na⁺ > 30 mg/LOver-dosing sodium bicarbonate (`NaHCO3`) or brewing through an ion-exchange water softener that swaps calcium/magnesium (`Ca²⁺`/`Mg²⁺`) for two sodium ions (`2 Na⁺`), exceeding the SCA `10 mg/L Na⁺` ceiling.Switch alkalinity buffer from sodium bicarbonate (`NaHCO3`) to potassium bicarbonate (`KHCO3`), or never exceed `45 ppm as CaCO3` from `NaHCO3` (`~20.6 mg/L Na⁺`).
14. Gassy, Bubbly Bloom & Metallic Bite (Too Fresh / High CO₂)Massive volcanic bloom crust that repels water; cup tastes carbonic, metallic, and unevenly extracted (`< 18.5% EY`).Roast Age 0 – 3 Days Post-RoastRoast degassing kinetics: freshly roasted coffee holds `1.0%–2.0%` by weight pressurized `CO2` (`5–10 L/kg`). Rapid outgassing during wetting forms a hydrophobic gas barrier around grinds and dissolves carbonic acid (`H2CO3`) into the cup.Rest light-roast filter beans 7–12 days (and light-roast espresso 10–18 days) post-roast, or extend your pre-wetting bloom to 60–90 seconds at `3×` dose weight; see Guide #6.
15. Wet Cardboard / Papery Filter TaintWoody, wet-newspaper, or brown-paper-bag aroma in the nose and finish of a delicate pour-over.Unrinsed or Unbleached Paper FilterWater-soluble hemicellulose, lignin oligomers, and guaiacol volatiles leach out of unbleached (brown) or unrinsed bleached cellulose filter paper during the first 60 seconds of contact.Use oxygen-bleached (`TCF/ECF`) white paper filters and pre-rinse with `150–200 mL` of hot tap water before adding dry grounds; see Guide #9.
16. Scalded, Smoky, Rubbery Dark-Roast CupBurnt rubber, tobacco ash, and acrid bitterness when brewing a second-crack dark roast.Brew Temp > 94°C (201°F) on Dark RoastHigh porosity and brittle cellulose walls of dark-roasted beans allow instant mass transfer; water above `92°C` exponentially accelerates the dissolution of high-activation-energy bitter phenylindanes and smoky guaiacols.Drop brew water temperature to 83°C–88°C (181°F–190°F), coarsen grind to `700–850 µm`, and target a lower `18.0%–19.2% EY` at `1:14–1:15` ratio; see Guide #7.

2. Mass-Transfer Kinetics and Percolation vs. Immersion Extraction Equations

Why do we need two different mathematical equations to compute Extraction Yield (`EY%`) from a refractometer `TDS%` reading depending on whether we brewed a V60 pour-over (`percolation`) or a French press (`immersion`)?

1. Drip Percolation & Espresso Equation (Fresh Water Enters Top; Extract Leaves Bottom):
   • Standard Form:
     Mass_Solubles (g) = Mass_Beverage (g) × (TDS% ÷ 100)
     EY_percolation (%) = (Mass_Beverage × TDS%) ÷ Mass_Dose

   • Interstitial-Corrected Form (Accounting for Retained Liquid Ratio, LRR):
     Because the liquid retained in the spent coffee bed at the end of a drip brew
     has a lower average concentration than the early-draining cup (~0.35 × TDS%),
     Exact Percolation EY% ≈ ((Mass_Beverage + 0.35 × Mass_Retained) × TDS%) ÷ Mass_Dose

2. Full Immersion Equation (French Press, Cupping, Clever Dripper):
   • Because the coffee grounds and all brew water sit in a single well-mixed slurry,
     the liquid trapped inside the spent grounds has the EXACT SAME concentration (TDS%)
     as the decanted cup!
   • Exact Mass-Conservation Form:
     EY_immersion (%) = (Mass_Total_Water × (TDS% ÷ 100)) ÷ (Mass_Dose × (1 - (TDS% ÷ 100))) × 100
   • Standard Simplified Immersion Form:
     EY_immersion_approx (%) = (Mass_Total_Water × TDS%) ÷ Mass_Dose

3. Post-Brew Bypass Dilution Conservation Equation:
   TDS_final (%) = (Mass_Beverage × TDS_initial%) ÷ (Mass_Beverage + Mass_Bypass)

During extraction, dissolution from ground coffee particles obeys **Noyes-Whitney dissolution** and **two-stage Fickian diffusion**:

  • Stage 1 — Fast Surface Wash (`0–30 seconds` in filter, `0–8 seconds` in espresso): Grinding fractures roasted bean cell walls across the exterior of each particle. Hot water immediately dissolves exposed soluble solids on those fractured surfaces. Highly polar, low-molecular-weight **organic acids** (citric `192.12 g/mol`, malic `134.09 g/mol`, quinic `192.17 g/mol`), **inorganic potassium/phosphate salts**, and **caffeine** (`194.19 g/mol`) elute rapidly during this initial wash.
  • Stage 2 — Slow Intra-Particle Pore Diffusion (`30–210 seconds` in filter, `8–30 seconds` in espresso): Water must diffuse inward through intact `20–40 µm` cellular pores of the larger grind fragments (`boulders`), dissolve intermediate-molecular-weight **caramelized Maillard sugars, furans, and volatile esters**, and diffuse back out against the concentration gradient into the bulk slurry. Finally, high-molecular-weight **melanoidins, chlorogenic acid lactones, and phenylindanes** elute slowest—which is why cutting a brew too early yields a sour, salty, hollow cup (`< 18% EY`), hitting the **`19.0% to 22.0% EY` SCA sweet spot** balances fruit acidity with syrupy sweetness, and pushing past `22.5%–23.0% EY` (or channeling locally) floods the finish with dry astringency and bitterness.

For full mathematical derivations and worked numerical examples, read Coffee Extraction Yield and TDS Math: Percolation vs. Immersion Equations, Bypass Brewing Math: Separating Extraction Yield from Final Beverage Strength, and Refractometer Brix-to-TDS Conversion and Temperature Calibration Errors.