Wet‑hulled Indonesian coffees can taste muddy if you brew them like a typical washed Central. Here’s how soil, microclimate and giling basah shape solubility, and how to adjust grind, water, agitation and filters to pull clean, sweet cups from Sumatran, Sulawesi and Java lots.
If you’ve ever brewed a Sumatran and thought, “Why does this taste earthy or muddy?”, you’re not alone. Wet-hulled coffees are different. They’re shaped by volcanic soils, humid microclimates and giling basah processing. And they respond to brewing tweaks in ways washed Centrals don’t. We’ve dialed in thousands of cups across Mandheling, Lintong, Gayo, Toraja, Java and Bali. Here’s the system we use to hit clarity and sweetness consistently.
The three pillars: soil, microclimate and giling basah
Volcanic soils in Sumatra, Java and Bali are rich in minerals and often produce dense, big-bodied beans with chocolate-forward notes. Combine that with high humidity and intermittent sun during harvest, and you get slower drying and higher internal moisture at key stages.
Giling basah removes parchment at higher moisture than fully washed coffee. The beans then dry more quickly. That creates a more porous structure and prominent silver-skin fragments. In brewing terms, that means faster initial extraction, more fines migration and a stronger tendency toward silt. If you brew with aggressive agitation or very hot water, you’ll amplify earthiness and lose sweetness.
Practical takeaway. Expect high body and low to medium acidity. Use gentler agitation, slightly cooler water than you use for washed Ethiopians and filters that control fines.
A step-by-step brew path that actually works
Think of your dialing-in in three phases.
Phase 1. Baseline brew for any wet-hulled lot
- Ratio. 1:16 for pour-over. Start with 18 g coffee to 288 g water.
- Grind. One click coarser than your usual V60 grind for washed Centrals. Aim for a 2:45–3:15 total time on a 1-cup V60.
- Water temperature. 90–92 C for medium roasts. 88–90 C if the roast is medium-dark.
- Agitation. Rinse the paper thoroughly. Bloom 40 g for 35–45 seconds with two gentle swirls. Then pour steadily in concentric circles, avoiding hard center pours that kick up fines. No aggressive stirring.
- Finish with a 5–8% bypass. Add 15–25 g of hot water after drawdown to lift clarity without overextracting the bottom of the bed.
This simple bypass is a non-obvious lever. It lets you keep the brew bed calm while still achieving the cup strength you want.
Phase 2. Tune for sweetness vs clarity
- Too earthy or muddy? Coarsen one notch, keep temp 90–92 C and add 5 g more bypass. Or switch to a thicker paper. You’ll trade a touch of body for more definition.
- Too flat or thin? Finer by half a notch and raise water to 92–93 C. Reduce bypass to 0–10 g. Keep agitation gentle.
- Dry, gritty finish? That’s fines. Rinse paper longer, lower pour height and avoid mid-brew stirring.
Phase 3. Lock repeatability
Once you find a target, lock two variables. Keep water temp fixed and adjust only grind to control time. Keep your bloom weight and time constant. We see the biggest day-to-day variance come from agitation, so standardize your pour height and pattern.
Common questions we hear every week
Why does my Sumatran coffee taste earthy or muddy?
Partly origin, partly technique. Wet-hulled Sumatran beans have more exposed pores and often carry micro-fines after grinding. If you use a metal filter or stir aggressively, you pull more insoluble solids into the cup. Combine that with higher extraction from hot water and you accentuate humus and tobacco instead of cocoa and molasses. The fix is simple. Cooler water, gentle agitation, a good paper filter and a touch of bypass.
If you enjoy classic earthy profiles but want them cleaner, try lots like Sumatra Mandheling Green Coffee Beans or Sumatra Lintong Green Coffee Beans (Lintong Grade 1). Lintong tends to run cleaner and nuttier. Mandheling leans chocolatey with mild acidity.
What is giling basah and how does it change brewing?
Giling basah is wet hulling. Parchment is removed at higher moisture, and beans finish drying without the shell. You get big body and those signature herbal-chocolate notes. But you also get faster extraction at the start of the brew and more fines in the cup if you’re not careful. That’s why we prefer thicker paper, a slightly coarser grind and controlled pouring.
What brew method works best for wet-hulled beans?
For clarity with body, paper-filter pour-overs like V60, Kalita or flatbeds are our go-to. For maximum body, French press with a paper-lined decant works well.
A reliable V60 recipe for Sumatran Mandheling. 18 g in, 288 g out. Water at 91 C. Bloom 40 g for 40 seconds. Two main pours to 180 g, then to 288 g by 2:10. Total time 2:50–3:10. Optional 15 g bypass.
French press vs pour-over. If you love syrupy texture, press at 1:13, 92 C, 4 minutes. Then break crust, skim top, and decant through a rinsed paper into your cup for clarity. You’ll get press body without muddy silt.
What water temperature should I use for Sumatran pour-over?
We recommend 90–92 C for medium roasts. 88–90 C for medium-dark and aged profiles. If your water is very soft, you can push to 92–93 C to improve extraction without harshness. With very hard water, stay at 90–91 C to avoid bitter-tannic edges.
How do paper vs metal filters change Indonesian coffee taste?
- Paper filters accentuate sweetness, trim earthiness and reduce silt. Great for wet-hulled.
- Metal filters amplify body and oils. Expect more earthy and spicy notes, plus more insolubles.
- Cloth sits between them, with creamy texture and good clarity if maintained well.
If your goal is to reduce muddiness, choose paper. Thicker papers work best.
Does roast level change the ideal recipe for wet-hulled coffee?
Yes. Roast depth shifts solubility.
- Light-medium wet-hulled lots are rare and can taste herbal if underextracted. Use 92–93 C, finer grind and keep agitation gentle.
- Classic medium roasts sing at 90–92 C with our baseline method.
- Medium-dark or aged profiles like Musty Cup Green Coffee Beans (Aged Arabica) are soluble. Drop to 88–90 C, coarsen slightly and add a small bypass to keep sweetness high.
Which Indonesian regions offer cleaner cups if I don’t like heavy earthiness?
If you want high clarity with Indonesian character, start with these.
- Bali Kintamani. Citrus and florals with a clean finish. Try Arabica Bali Kintamani Grade 1 Green Coffee Beans or Bali Natural Green Coffee Beans.
- Java Ijen and Preanger. Spicy-chocolate, bright acidity. See Arabica Java Ijen Grade 1 Green Coffee Beans or Java Preanger Grade 1 Green Coffee Beans.
- Sulawesi Toraja. Full body but surprisingly clean and spicy-herbal. Explore Sulawesi Toraja Green Coffee Beans (Sulawesi Toraja Grade 1).
- Blue Batak and select Lintong lots from North Sumatra can be very tidy with nutty-vanilla aromatics. See Blue Batak Green Coffee Beans and Sumatra Lintong Green Coffee Beans (Lintong Grade 1).
If you’re choosing green coffee for your menu, browse our current export-ready list. View our products.
Two advanced levers most people miss
- Water chemistry. Wet-hulled coffees love balanced water. Aim for 40–55 mg/L alkalinity as CaCO3, 50–90 mg/L total hardness with some magnesium. Too little alkalinity and bitterness spikes. Too much and the cup flattens into cardboard. A small magnesium bump often lifts chocolate and caramel in Sumatran profiles.
- Temperature staging. Bloom at 88–90 C, then brew at 91–92 C. The cooler bloom reduces fines mobilization and earthy volatiles. The slightly hotter main pours improve sweetness. This small split consistently lifts clarity for us.
Troubleshooting cheat sheet
- Muddy, heavy, dull. Coarsen one notch. Use thicker paper. Reduce agitation. Add 5–15 g bypass.
- Hollow or sour. Finer grind. Raise temp 1–2 C. Extend contact time by 10–15 seconds.
- Bitter-tannic aftertaste. Lower temp 1–2 C. Reduce pour height. Keep the bed flat. Check water alkalinity isn’t below 30 mg/L.
- Silty cup. Rinse paper more. Avoid center punching. Consider a flatbed dripper for more even drawdown.
Storage and freshness for Indonesian beans
Wet-hulled beans and aged Indonesians behave differently after roasting. They often peak a bit later. We rest medium roasts 4–7 days. Medium-dark and aged lots 7–12 days. Store in airtight bags with one-way valves and keep them cool and dry. If you’re a roaster handling green coffee, maintain ≤13% moisture and rotate stock. Aged profiles like Past Crop Green Coffee Beans and Musty Cup Green Coffee Beans (Aged Arabica) are stable blenders and excel when low acidity is desired.
Where soil and microclimate meet the cup
Sumatra’s highlands build body and chocolate through mineral-rich volcanic soils and frequent mist that slows cherry drying. Java’s Ijen Plateau delivers clean spice because of higher diurnal swings. Bali Kintamani’s citrus and florals ride on lava-derived soils and organized farmer groups that prioritize clean washing. Understanding that lineage helps you pick the right technique. Want syrupy cocoa? Keep temps moderate and agitation minimal on Mandheling. Want sparkle? Choose Kintamani and brew a touch hotter with a thinner paper.
If you’re working on a specific lot and want a second set of eyes on your water or recipe, we’re happy to share what’s worked across our partner roasteries. Need a quick consult? Reach out and we’ll troubleshoot together. Contact us on whatsapp.
Brewed with intention, wet-hulled Indonesian coffee isn’t muddy. It’s layered. Chocolate, spice, cedar, caramel and a calm, sweet finish. With the right paper, a gentler hand and water that supports sweetness, you’ll taste what our producers work so hard to deliver.