How the simulator models Moka pot extraction

Moka pot in the simulator

The Moka pot (Italian stovetop brewer) is the only method in the simulator that uses direct heat as a control variable instead of pre-measured water temperature. Water in the lower chamber heats on the stove, generates pressurized steam (1–2 bar, much lower than espresso) and rises through the ground coffee into the upper chamber.

The simulator models the Moka pot with three basic parameters: grind, ratio and heat level. Advanced mode adds initial water temperature.

Model note: the simulator does not measure real extraction, but a heuristic index (0–100) that combines the brewing variables. That index determines both the position on the extraction map and the shape of the flavor radar. It is not a TDS percentage or a real extraction yield (EY).

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Simulator variables: Moka pot

Grind (0–100)

Grind has the highest extraction weight in the Moka (up to 35 points in the model). Finer = more extraction; but unlike espresso, too fine a grind in the Moka has additional consequences: it can cause channeling, block water flow and produce burnt or very bitter flavors in real practice.

The simulator does not directly model channeling, but the effect is reflected in that very fine grinds combined with high heat quickly push to over-extraction and high bitterness in the radar.

Recommended range in practice: medium-fine, between espresso (very fine) and V60 (medium). In the simulator, values of 60–80 are representative.

Ratio (1:5–1:10)

The Moka pot ratio goes from 1:5 to 1:10 (water-to-coffee). This is the most concentrated range of the hot-water methods in the simulator, after espresso.

• Low ratio (< 1:7): more concentration, high body. The model adds up to 16 body bonus points for low ratios.
• Standard ratio (1:7): usual working zone.
• High ratio (> 1:8): more diluted drink, less body.

In real practice, the Moka ratio is partly determined by the brewer size and the water line markings inside.

In the model, ratio does not only dilute the drink: it also increases the extraction index by extending the water–coffee contact. A longer ratio means more water passing through the bed, extracting more solubles even at equal grind and heat level.

Heat level (1–5)

Heat level is the most characteristic parameter of the Moka pot. In the simulator it goes from 1 (very gentle) to 5 (very strong). It models the flame intensity or burner power.

• High heat: greater extraction (up to 12 points), but significantly raises bitterness and astringency in the radar. The model applies a bitterness bonus of (heatN − 0.5) × 8 and astringency of (heatN − 0.5) × 5.
• Gentle heat: less extraction, but a more balanced sensory profile. Also reduces acidity (acidity is modulated inversely: (0.5 − heatN) × 6).

The standard recommendation in real practice is medium-low, constant heat. The simulator reflects that high heat, while extracting more, deteriorates the sensory profile disproportionately.

Estimated time in the Moka pot is calculated inversely to heat level: estimatedTimeS = 300 − heatLevel × 40. Higher heat = faster cycle (heat 5 → ~100 s; heat 1 → ~260 s).

Initial water temperature (advanced, 20–95 °C)

The initial water temperature in the lower chamber is the Moka pot's advanced parameter. Default is 20 °C (cold tap water).

• Pre-heated water (> 60 °C): reduces the time water spends in the lower chamber being heated before extracting. This limits over-heating of the coffee bed and produces a cleaner profile. The model adds up to 8 extraction points for this variable (water at 95 °C = maximum).
• Cold water (20 °C): water takes longer to boil. In practice, this can produce a more toasted or bitter profile because the coffee is exposed to heat for longer.

This parameter is especially relevant at high heat levels, where the total cycle is short and pre-heated water can make a perceptible difference in the profile.

Water hardness: GH and KH (advanced)

Same as other methods:

• High GH: more body and sweetness.
• High KH: reduces perceived acidity.

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How it reflects in the extraction map

The map positions the recipe in the grind-ratio space:

• The balanced zone for the Moka is reached with medium grinds (55–75) and medium ratios (1:6–1:8).
• Heat level is a secondary modifier that shifts the point vertically (toward more extraction at high heat).
• Initial water temperature also shifts the point toward more extraction.

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How it reflects in the flavor radar

The radar does not represent isolated flavors, but the overall balance of the simulated extraction. Each axis reflects how the extraction index and the modifiers for roast, process and advanced parameters combine in the specific Moka pot you have configured.

The Moka radar has its own characteristic profile:

• High body base (28): between French Press (35) and espresso (25). Moka produces concentrated, full-bodied drinks.
• Moderate acidity base (72): starting point 72 − E×0.7. Moka acidity is less than V60 but more than French Press.
• Sweetness bell at E=52: the Moka reaches peak sweetness at extraction 52, very similar to espresso.
• Heat sensitivity: high heat raises bitterness and astringency more than any other parameter in the method.

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Typical combinations and common readings

| Scenario | Symptom | Why it happens | Suggested adjustment | |---|---|---|---| | Watery or acidic cup | Under-extracted | Coarse grind or very low heat → low index | Grind finer or moderately increase heat | | Strong, dry bitterness | Over-extracted | High heat or fine grind → high index + heat bitterness bonus | Lower heat or grind coarser | | Burnt or metallic | Very high heat + fine grind | Engine applies bitterness and astringency bonuses directly proportional to heat | Use heat 2–3, medium grind | | Good intense balance | Heat 3, grind 65–70 | Medium heat balances extraction index and sensory profile | Target zone | | Softer profile | Pre-heated water + low heat | Pre-heated water raises extraction slightly without triggering heat bitterness bonus | Initial temp > 70 °C |

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Balanced, under-extracted and over-extracted in Moka pot

Under-extracted: extraction below 42. The Moka pot under-extracted produces an acidic, watery cup without the characteristic body of the method. In practice, this usually occurs with too-coarse a grind or very low heat.

Balanced: extraction in the optimal zone (42–70 for medium roast; 42–74 for light; 42–65 for dark). A balanced Moka has intense body, moderate sweetness and contained bitterness. The balanced zone for the Moka is wider in the simulator than for espresso, reflecting that the method tolerates somewhat more variation.

Over-extracted: extraction exceeds the threshold. Bitterness and astringency rise quickly. In real practice, Moka over-extraction typically produces burnt or metallic flavors that are difficult to mask.

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Technical section: how the simulator models the Moka pot

General heuristic

extraction = 15 + grindN×35 + ratioN×18 + heatN×12 + waterTempN×8

Where:

• ratioN = (ratio − 5) / 5 (range 5–10)
• heatN = (heatLevel − 1) / 4 (range 1–5)
• waterTempN = clamp((waterTempC − 20) / 75, 0, 1) (range 20–95)

The starting point is 15, the highest of the pour-over/immersion methods (espresso starts at 18). Grind has the highest weight (35 points), comparable to espresso's. Heat level (12) has similar weight to temperature in espresso (6) but higher, reflecting that in the Moka pot heat controls both extraction speed and the final profile.

Estimated time

Estimated time is not an output of the extraction engine but a direct function of heat level: estimatedTimeS = 300 − heatLevel × 40. It does not feed back into the extraction calculation.

Sensory projection

• Acidity: descending function of E, inversely modulated by heat: (0.5 − heatN) × 6. High heat reduces acidity.
• Bitterness: ascending function from E=48, with direct heat modulation: (heatN − 0.5) × 8.
• Astringency: ascending function from E=52, with heat modulation: (heatN − 0.5) × 5.
• Sweetness: bell at E=52 with a peak similar to espresso.
• Body: ascending function of E with base 28. Low ratio adds up to 16 bonus points.

Simplifications and limits

• Heat level (1–5) does not represent degrees or watts. It is a relative intensity index.
• The model does not reproduce channeling, steam buildup or the Moka pot's characteristic gurgling sound as it finishes.
• Initial water temperature is simplified: the model only captures its effect on total extraction, not its influence on extracted water temperature or actual cycle time.
• The model does not account for filling the basket at different levels (coffee compaction in the basket).

The model prioritizes interpretability over physical precision: the goal is for the user to understand how to adjust variables and develop extraction intuition, rather than exactly reproducing the behavior of a real Moka pot.