At 2,043 meters, Kanzu sits at the top of Rwanda's altitude range, and that matters for what medium roasting does to this specific bean.
High-altitude Bourbon accumulates more organic acids and volatile precursors during its extended cherry maturation window. Cooler nights mean photosynthesized sugars are preserved rather than respired away — the diurnal temperature differential of 8–10 degrees Celsius between day and night is the mechanism. The seed arrives at the roaster with higher soluble density than lower-altitude lots, and altitude explains roughly 25% of variation in extraction yield. This is not a bean short on raw material.
Medium roasting then changes the acid chemistry in ways that light roasting wouldn't. Development past first crack degrades chlorogenic acids — the primary bitterness and astringency compounds at light roast — into quinic acid and caffeic acid. It also degrades citric and malic acids progressively. The light roast brightness that 2,043m Bourbon naturally produces gets pulled back: less citric-forward acidity, more Maillard complexity. Melanoidin content increases with extended development, building body and mouthfeel that a light roast on the same bean would not deliver.
The sweetness paradox is relevant here: sucrose is nearly 100% consumed during roasting at both light and medium levels, yet perceived sweetness increases through the light-to-medium development window. Caramelization products — furanones, maltol — create olfactory sweetness that peaks somewhere in medium territory before pyrolysis compounds begin building and sweetness drops off.
Washed processing gives the terroir a direct expression — fermentation in tanks strips mucilage, leaving no fruit-processing variables between altitude and cup. At 2,043m with [washed processing](/blog/coffee-processing-methods-explained), the extraction yield ceiling is high, and medium roast opens more of those solubles than a light roast would. That's the trade-off: less brightness, more body and extraction efficiency.
The AeroPress's full immersion combined with pressure-assisted plunge gives it the highest match score here (tied with Clever Dripper at 88) for a specific reason: immersion contact time is controlled entirely by steep duration, not pour skill, and medium-roasted high-density Bourbon benefits from that consistency. The recipe drops temperature to 83°C — significantly lower than any other method for this bean. This is a function of both roast level (-2°C) and the AeroPress's characteristic: lower temp extracts more slowly, which in an immersion context means a cleaner, less bitter extraction. At 370μm (30μm below default) and a 1:13 ratio, this setup pulls body and Maillard complexity without the risk of extraction of bitter compounds. The 1-2 minute range gives a wide window.
Troubleshooting
sour: Grind finer by ~22μm and increase temp by 1°C, to 84°C. Even at 83°C, very high density 2,043m Bourbon may stall extraction before sweetness compounds dissolve if your grind is inconsistent. The AeroPress's short steep means any extraction deficit shows up immediately as sourness.
thin: Increase dose by 1g or reduce water by 15g; try a metal filter instead of paper. AeroPress paper filters strip the melanoidin-rich oils that medium roast development on this high-altitude Bourbon builds. Switching to metal passes that body directly into the cup.
The Clever Dripper is a hybrid: full immersion during steep (like French press), paper-filtered drawdown (like Chemex). For this washed Rwanda Bourbon at 2,043m and medium roast, the immersion phase allows consistent contact time that doesn't depend on pouring technique, and the paper filter then produces a cleaner cup than French press would. Immersion consistency combined with filter clarity suits a medium-roasted bean that has developed Maillard complexity you want to showcase without sediment interference. At 500μm and 92°C, the recipe is nearly identical to the Kalita Wave setup, but the steeping mechanism means grind consistency matters less — even slightly coarser-ground portions extract during immersion where they'd under-contribute in a continuous-flow brewer.
Troubleshooting
sour: Grind finer by ~22μm and increase temp by 1°C. The Clever Dripper's steeping phase should be sufficient for this dense Bourbon's solubles to dissolve, but if your grind is inconsistent or steep time is cut short, the fast-extracting acids dominate. A full 3-4 minute steep at 500μm is the target.
thin: Increase dose by 1g or reduce water by 15g. The paper filter removes some of the melanoidin-carrying oils that this medium roast developed. The Clever Dripper's immersion phase extracts more thoroughly than a pour-over at the same grind, so a slight ratio adjustment is usually enough to restore body.
The V60's conical geometry and fast-draining design demand active technique — pouring pace and swirl timing control how evenly water contacts the coffee bed. For this 2,043m Rwanda Bourbon at medium roast, that technique-dependence works in your favor: the bean's very high density means it holds solubles tightly, and the conical bed depth creates longer water contact compared to a flat-bottomed brewer. The 470μm grind (30μm finer than a standard medium-roast Rwanda would need) compensates for that density. Temperature at 92°C sits 2°C below default for medium roast — medium development on high-altitude Bourbon doesn't need the same push as a light roast to dissolve its solubles, and the extra 2°C would risk pulling too far into the astringent bitter compound range that medium development has already begun degrading.
Troubleshooting
sour: Grind finer by ~22μm and increase temp by 1°C. At this altitude, the Bourbon's dense cell structure resists full extraction; sourness means you're pulling only the first wave of fruity acids before the Maillard sweetness compounds can dissolve. Finer grind closes the extraction gap.
thin: Increase dose by 1g or reduce water by 15g. High-density 2,043m Bourbon yields well when extraction conditions are right, but if your pour is too fast or inconsistent, TDS drops. A metal filter will also pass more oils and body-building melanoidins than paper.
The Kalita Wave's flat-bottomed, three-hole design produces the most even extraction among the pour-over methods — water distributes evenly and exits slowly enough to maintain contact time without technique-induced variability. For this washed Rwanda Bourbon at 2,043m, that evenness is worth noting: very high density beans can produce uneven extraction in steep-sided brewers because denser particles at the base contact water differently than those at the cone's upper edges. The flat bed eliminates that geometry variable. The recipe calls for 500μm (30μm finer than standard), 92°C, and a 1:17 ratio — this is a forgiving setup for a bean with high soluble density. The 3:00-4:00 window is wider than the V60's, appropriate for a brewer that tolerates pulse variation without channeling.
Troubleshooting
sour: Grind finer by ~22μm and increase temp by 1°C. This 2,043m Bourbon is very dense — at 500μm it's already 30μm below neutral, but if your grinder runs wide, you may need to push further. Sourness here means the flat-bed's even extraction hasn't reached the Maillard compounds past the acid layer.
thin: Increase dose by 1g or reduce water by 15g. The Kalita Wave's even extraction profile means thin cups usually reflect a dose-ratio problem rather than technique error. High-altitude Bourbon has the extraction ceiling to support a stronger ratio — lean on it.
The Chemex's thicker bonded filter — roughly 20-30% denser than standard paper — removes oils and fine particles aggressively. On this washed Rwanda Bourbon at medium roast, that filter behavior is a specific tradeoff: the oils that contribute to the roast-developed mouthfeel from medium development get stripped, leaving a cleaner but lighter-textured cup. The 520μm grind (30μm finer than altitude-neutral default) and 92°C temperature are calibrated to compensate. The slightly coarser grind than V60 and Clever Dripper (520 vs 470-500μm) reflects the Chemex's naturally slower flow — finer grinds risk over-restriction and channeling. Washed processing means no extra mucilage solubles to compensate for filter removal, so dialing in the dose-to-water ratio matters more here than on a natural-process bean.
Troubleshooting
thin: Increase dose by 1g or reduce water by 15g. The Chemex filter removes body-contributing oils that medium roast development built from this 2,043m Bourbon. Pushing the ratio slightly stronger compensates for what the thick paper strips. A metal filter replacement is also an option if you prefer more texture.
sour: Grind finer by ~22μm and increase temp by 1°C. The Chemex's slow drawdown can paradoxically underextract if the grind is too coarse — water passes before full solubles dissolution. Medium roast on dense Bourbon needs a finer contact to get past the fast-extracting acids into sweetness.
Espresso at 91°C (2°C below standard) and 220μm grind (30μm finer than a standard-altitude medium roast default) concentrates the Bourbon's medium-roast chemistry under 9 bars of pressure. At this pressure, extraction yield reaches 18-22% in 25-30 seconds — the same target as filter methods, but at 8-12% TDS instead of 1.4-1.6%. What that means for this specific bean: the Maillard compounds and residual citric and malic acids from medium-roasted 2,043m Bourbon become intensely concentrated. The temperature at 91°C helps avoid over-extracting the bitter compound range that medium development has already partially degraded — pushing hotter risks tipping from pleasant acidity into astringent bitterness. At 1:2 ratio, this setup aims for a balanced, textured shot rather than a bright, fast ristretto.
Troubleshooting
sour: Grind finer by ~10μm and increase temp by 1°C. Espresso's short extraction window means sour shots are typically under-extracted — water moved through the puck too fast. For this very high density Bourbon, even 10μm makes a meaningful difference in puck resistance and contact time.
bitter: Grind coarser by ~10μm and decrease temp by 1°C. Medium roast on high-altitude Bourbon already carries more CGA decomposition products than a light roast — if the shot runs long or too hot, bitter dry distillates come forward. Minor adjustments matter more in espresso than any other method.
The moka pot generates approximately 1.5 bar of pressure — not true espresso, but enough to force pressurized water through the coffee bed and extract at higher TDS than filter methods. For this medium-roasted Rwanda Bourbon, pre-boiling the water before filling the base chamber is critical: it prevents the grounds from slow-cooking on steam heat before pressurized water reaches them, which would over-extract bitter compounds before the cycle even runs. At 320μm (30μm finer than default for this altitude) and 98°C water in the base, the setup extracts cleanly at roughly 1:10 ratio. The medium roast's increased body from roast development means this bean produces more body in moka pot output than a lightly roasted Bourbon would — a useful property given how small the serving volume is.
Troubleshooting
sour: Grind finer by ~22μm and ensure you're using pre-boiled water. At 320μm with this very high density Bourbon, sour notes usually mean insufficient extraction — the dense bean resists water penetration. Pre-boiling water eliminates the slow-heat phase that would otherwise under-extract.
strong: Reduce dose by 1g or increase water by 15g. Medium-roasted high-altitude Bourbon extracts efficiently in the moka pot's pressurized environment. The 1:10 ratio is already on the concentrated side — a small adjustment avoids overstrength without thinning the cup's texture.
French press is the only unfiltered method in this brewer set, and that matters for medium-roasted high-altitude Bourbon: the oils and insoluble solids that paper filters strip pass freely through the metal mesh. The body-building compounds from roast development that medium development accelerates on this very high density bean — are preserved completely in the cup. The recipe calls for 970μm (coarse, 30μm below default for this altitude) and 94°C, slightly above the standard pour-over temp. The temperature elevation helps compensate for the coarser grind's reduced surface area. The 4:00-8:00 steep range is wide; leaning toward the 8-minute end (using Hoffmann's approach of waiting after pressing for grounds to settle) produces a markedly cleaner cup than a 4-minute plunge, despite no additional filter.
Troubleshooting
sour: Grind finer by ~22μm and increase temp by 1°C. In French press, sour means you're not reaching the Maillard and caramelization compounds behind the acid layer — a function of grind size being too coarse for this particular very high density Bourbon from 2,043m. Extend steep time first; if still sour, adjust grind.
strong: Reduce dose by 1g or increase water by 15g. French press's full immersion and unfiltered delivery means TDS runs higher than pour-over at similar ratios. Medium-roasted high-altitude Bourbon extracts efficiently — a modest ratio adjustment pulls it back without sacrificing body.
Cold brew's low extraction efficiency is the core challenge for this bean. Medium-roasted high-altitude Bourbon contains more melanoidin content than a light roast — but melanoidins are temperature-sensitive in extraction, and cold water (2°C) dissolves them at a fraction of the rate hot water would. The result is that cold brew undersells this bean's body potential: you get the sweet, low-acid cup that cold process produces, but with less structural weight than the same bean brewed hot. At 870μm (still 30μm finer than altitude-neutral default) and 1:7 ratio, this recipe compensates by using a stronger concentrate ratio. The 12-18 hour window is standard; science shows caffeine and CGA extraction plateaus around 7 hours, but melanoidins and other body compounds continue extracting slowly — leaning toward 14-16 hours improves body for this bean.
Troubleshooting
flat: Grind finer by ~22μm and increase to 4°C; check water mineral content. Flat cold brew from this washed Bourbon typically means insufficient extraction — cold process already suppresses Maillard compound dissolution, and very soft water compounds that problem. Medium-hard water (150-200 ppm) extracts more efficiently.
thin: Increase dose by 1g or reduce water by 15g. Cold brew from a medium-roasted high-altitude bean will always trend lighter-bodied than hot brew from the same bean — cold water poorly solubilizes melanoidins. A slightly stronger concentrate ratio is the most direct correction.