A practical, monsoon-proof setup for shipping Indonesian green coffee. Exactly how to choose GrainPro or Ecotact, which liners fit 60 kg jute, the right sealing method, how many desiccants to use, and how to verify water activity under 0.60 on arrival.
We’ve shipped Indonesian green coffee through more monsoon seasons than we care to count. When humidity spikes and transit times stretch, mold doesn’t ask for a second chance. In this guide, we’ll cut through brand noise and show exactly how we keep water activity under 0.60, which hermetic liners to choose, how to seal them properly, and how many desiccant poles a 20-foot container really needs.
The 3 pillars of monsoon‑proof coffee shipping
- Control water activity at the bag level. 2) Create a humidity buffer at the container level. 3) Verify on arrival and close the loop.
Here’s the thing. Mold risk in green coffee tracks water activity (Aw), not just moisture content. We target Aw ≤ 0.58 before bagging, then use hermetic liners to keep it stable, and we add container desiccants to handle “container rain.” That combination has saved more shipments than any single product choice.
Weeks 1–2 before stuffing: measurement and materials
- Water activity. Calibrate your meter, homogenize samples and measure Aw on ground green coffee. We like a 3‑reading average per lot, target ≤ 0.58. If you’re at 0.60–0.62, hold, recondition with airflow for 12–24 hours and recheck.
- Choose the liner. GrainPro and Ecotact both work. The differences that actually matter are closure workflow, film feel, and thickness options. For 60 kg jute bags we recommend liners in the 80–100 micron range. Thinner films save cost but puncture more easily on jute weave and bean edges.
- Plan desiccants. Hermetic liners don’t eliminate container condensation. In our experience, 8–12 container desiccant poles for a 20‑foot is the sweet spot on humid routes. If you’re routing during heavy monsoon or via longer detours, push to 12. For 40‑foot, think 16–22 depending on risk.
Practical takeaway: If you only change one thing, measure Aw and set a go/no‑go threshold at 0.60. That’s where mold gets a foothold.
Choosing GrainPro vs Ecotact for 60 kg bags
Both are hermetic. Both dramatically reduce oxygen and moisture exchange compared to bare jute. The choice usually comes down to workflow and supply availability.
- Fit for 60 kg jute: Ask for 60 kg liners with enough headspace to fold and seal. We look for 10–15 cm of “lip” above the jute after filling, so there’s room to do a clean double heat seal. If the bag barely reaches the jute mouth, it will be hard to seal well.
- Film and handling: GrainPro tends to feel slightly softer and more pliable. Ecotact is often a stiffer, clear multi‑layer. Both are fine. What matters is the right thickness and that you can consistently make a strong, wide seal.
- Closure method: Zip tie or cable tie is fast but not as hermetic as a good heat seal. In our experience, a heat seal reduces oxygen ingress and moisture creep significantly during long, humid voyages.
When do we prefer one? On high‑risk monsoon routes or longer transit times, we lean toward whichever liner our team can heat‑seal fastest and most consistently. That’s the true performance driver.
Will a zip‑tie closure be enough to stop mold?
Short answer: We don’t trust zip ties alone during monsoon. They’re acceptable for short domestic hops or quick export transits, but for Indonesia‑to‑EU/US routes, go heat seal. Our field workflow is heat seal first. Then fold once and add a cable tie as a mechanical backup.
Loading week: the sealing setup that works in small mills
What heat sealer works for GrainPro or Ecotact in a small mill?
You don’t need a fancy line. A 12–16 inch impulse sealer with a 5–10 mm wide element works for most 60 kg liners. For throughput, a band sealer with temperature control is faster and more uniform.
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Recommended approach: Double seal. Two parallel seals 10 mm apart are far more reliable than one narrow seam.
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Heat settings: For poly liners, start around 170–200°C on a band sealer. On impulse sealers, increase the dwell time until you get a smooth, glossy bond without charring. Always do a quick “squeeze test” with air trapped in the liner before closing the jute.
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Operator tip: Wipe the seal area clean. Even small chaff fragments can cause pinholes. We’ve seen more failed seals from dirty bag mouths than from bad machines.
Do I still need desiccants if I use GrainPro or Ecotact?
Yes. Hermetic liners protect the beans. Desiccants protect the container environment. They work together. Without desiccants, you still risk “container rain” dripping from the roof or walls, which can wet jute and cause stains or localized mold on unlined bags.
How many desiccant poles for a 20‑foot container of coffee?
- Baseline tropics, standard transit: 8–10 poles (about 1 kg per pole).
- Monsoon or extended routes: 10–12 poles.
- 40‑foot containers: 16–22 poles depending on load plan and climate. Space them evenly along the walls and doors. Keep cargo 8–10 cm off walls to allow airflow.
Can hermetic liners prevent container rain and condensation stains?
They prevent moisture exchange with the beans, but they don’t stop condensation on steel surfaces. To reduce staining, line the roof with kraft paper, use desiccants, and avoid loading steaming‑hot coffee or wet pallets. We also use slip‑sheets between layers to create micro airflow channels.
Water activity control: staying below 0.60
How do I keep water activity under 0.60 during monsoon shipping?
- Pre‑ship: Do the Aw check after coffee equilibrates to packing room conditions. If Aw > 0.60, recondition with ambient airflow or light dehumidification, then recheck.
- Pack right away: Don’t leave filled but unsealed liners sitting overnight. Fill, heat seal, fold, and close the jute promptly.
- Container level: Use enough desiccants and keep cargo off the walls. Avoid loading during heavy rain if the flooring or pallets can wick moisture.
Testing water activity on arrival: a simple protocol
- Condition samples: Bring samples to room temperature in sealed bags for 30–60 minutes.
- Grind and measure: Grind a representative sample and measure Aw in a clean instrument cup. Take 3 readings per lot.
- Acceptance: We accept ≤ 0.60. Between 0.60–0.63, isolate, recheck the next day, and consider gentle reconditioning if needed. Document the bag condition and seal quality. If a lot arrives high, we usually find weak or single seals on a subset of bags.
GrainPro vs Ecotact: what actually changes in the cup?
Does hermetic packaging stop flavor fade? It slows it. Lower oxygen ingress reduces staling and “baggy” notes, especially on longer routes. But hermetic liners aren’t a nitrogen flush. Some fade still happens across 4–8 weeks of sea transit. We’ve noticed delicate lots like naturals and wine‑fermented coffees benefit the most.
If you’re buying fruit‑forward and higher‑risk lots, ask for hermetic by default. For example, we ship our Bali, Java, Gayo & Mandheling - Wine Green Arabica Coffee Beans and Arabica Bali Kintamani Grade 1 Green Coffee Beans with liners on monsoon routes. More classic, robust profiles like Sumatra Mandheling Green Coffee Beans still gain from hermetic plus desiccants when transits run long.
Note on aged styles: If you’re exploring intentionally aged profiles like our Musty Cup Green Coffee Beans (Aged Arabica), aging happens under controlled storage before export. We still ship hermetic in transit to avoid unintended mold.
5 mistakes that cause mold (and how to avoid them)
- Sealing dirty liners. Brush the mouth clean before sealing. Double seal every time.
- Overfilling bags. Leave 10–15 cm headspace. Tight bags create weak, wrinkled seals.
- Skipping desiccants. Hermetic bags don’t fix container rain. Use 8–12 poles in 20‑foot containers.
- Not measuring Aw. Moisture content isn’t enough. Commit to ≤ 0.60.
- Relying on cable ties. They’re convenient but not hermetic enough for monsoon shipping.
Resources and next steps
If you’re unsure whether GrainPro or Ecotact fits your workflow, choose the one your team can heat‑seal consistently with a wide, double seal. That’s the real differentiator. Want a quick sense check on your route, transit days, and monsoon risk? You can Contact us on whatsapp. We’re happy to recommend liner thickness, sealer settings, and a desiccant plan for your lanes.
If you’re evaluating lots for the season, browse our current Indonesian offerings and request samples. Start with View our products and tell us which profiles you’re targeting. We’ll set them up with the right hermetic plan from day one.
Final takeaway: GrainPro vs Ecotact matters less than execution. Measure Aw. Double heat seal. Use enough desiccants. That’s how you ship clean coffee through the wettest months and sleep at night.