Segmented Extraction Experiment: Revealing the Reality of Pulsed Pouring Through TDS and Flavor
Contents:
1. Why Practice Segmented Extraction?
2. Experiment Settings and Coffee Profile
3. Flavor Observations by Segment Combinations
4. Flavor Characteristics of Each Segment
Why Practice Segmented Extraction?
In specialty coffee brewing, flavor control goes beyond bean selection and roasting — it depends heavily on how water is poured during the brewing process. While segmented pouring is common in pour-over brewing, have we ever stopped to ask: What is actually being extracted in each phase? What flavors are drawn out at different points in time? This question touches on a key theoretical principle: Solubility rates and selective extraction.
Coffee solubles are not released all at once — they are extracted sequentially based on solubility speed. Early pour dissolves easily soluble compounds like acids and aromatic esters. Middle pour extracts sugars and the main aromatic body, while later pour brings out bitter, heavy compounds. Thus, segmented pouring isn't just a brewing method — it's a strategic tool for flavor design and control.
In this experiment, we used the 2025 TOH Ethiopia Champion Lot to conduct segmented extraction, measure TDS, and record sensory impressions — putting theory into practice.
Experiment Settings and Coffee Profile
Coffee Used: Ethiopia Guji Buku Sayisa “Kerume” Washed — 2025 TOH Grand Champion Lot
Original Cupping Notes: Floral, vanilla, honey, black cumin, berries, passionfruit, bright acidity, rich mouthfeel, creamy body, long and complex aftertaste.
Brewing Parameters:
Coffee dose: 20 g
Water temp: 90 °C
Grind size: ~1000 µm
Total water: 320 g
Extraction divided into three segments, each collected separately
When all three segments were blended (1 g from each), the resulting TDS was 1.47% — placing it on the high end of the Gold Cup recommendation, with a full-bodied and well-balanced profile.
Flavor Observations by Segment Combinations
Segment 1 + Segment 2: Gave the impression of “lemon candy” — rich sweetness, bright acidity, and complete fruitiness. This was the most balanced and harmonious blend.
Segment 1 + Segment 3: Reminiscent of “lemon black tea” — sweetness and tea-like notes, smooth texture, and a clean finish.
Segment 2 + Segment 3: Highlighted a “tea soup” character — light and clean, but lacking body and core flavor.
Flavor Characteristics of Each Segment
Segment 1 (Early Extraction) Correlates with highly soluble compounds like esters, organic acids, and some sugars. This phase creates the foundation of bright acidity and core sweetness. TDS: 2.78%, mellow and concentrated, buttery, honeyed, floral (vanilla, passionfruit), etc.
Segment 2 (Middle Extraction) Draws out complex sugars, aldehydes, and fruity acids — the heart of flavor complexity and structure. TDS: 1.08%, stable and clean, orange blossom, lemon, cane sugar, berry acidity.
Segment 3 (Late Extraction) Releases slow-solubility compounds like tannins and bitter alkaloids. TDS: 0.55%, mild but contributing to aftertaste and structural support, lemon peel, sugar water, tea-like clarity, adds transparency.
These three segments perfectly demonstrate the Selective Extraction Theory: flavor is not extracted all at once, but is instead released in stages.
By deconstructing a cup and mapping its structures, we can rebuild the logic behind the brewing. This experiment shows that “segmented extraction” is not just a vague habit — it's a flavor design method that can be validated through data and sensory feedback. Each phase not only affects TDS, but also determines the aroma, sweetness, acidity, body, and finish. By understanding this theory, using TDS measurement and flavor analysis, we can accurately break down and reassemble the soul of a cup — crafting clear, controllable, and diverse flavor profiles.
│Further reading: Practical Application of the VST Coffee Refractometer in Retail: From Brewing to Roasting – A Complete Workflow at Justin Coffee
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