What Characteristics Does Wet Hulling Impart to Mandheling? The Unique Herbal Notes of Sumatran Wet Hulling

FrontStreet Coffee - Introduction to Indonesian Wet Hulling

Coffee-producing countries typically have distinct dry and rainy seasons. For coffee, a crop that depends on the weather, the rainy days determine when it flowers and fruits. But in places like Indonesia, where it rains year-round, coffee trees flower and fruit in every season. That situation leaves the trees helpless and the farmers confused.

Coffee flowers are white.

What does this mean in practice? First, farmers must harvest throughout the year. Second, because of the lack of sunlight, drying coffee beans in humid Indonesia takes at least fifteen days. Even if the washed method completes fermentation, farmers may carry the coffee out to sunbathe in the morning only to haul it back indoors when the afternoon rain arrives.

March to May and September to December are the harvest seasons for Mandheling in Sumatra. Today most farmers pick only fully red cherries. After collecting cherries in the morning, they remove the skin and pulp in the afternoon, creating wet parchment beans, the form we call parchment coffee. These are then placed in water tanks to float off defective beans.

Sumatra's natural environment is excellent, and most of the water used comes from mountain springs. The dense, sinking beans are then taken out and placed in barrels for dry fermentation, allowing the pectin sugars to ferment fully and deepen the flavor. Fermentation usually lasts between 12 and 36 hours, depending on conditions.

Next, the beans are sun-dried for 1 to 2 days. When the moisture content reaches 35-40%, they are collected into woven bags, usually 40 or 80 kilograms per bag, and sent to processing plants for hulling.

Hulling means grinding off the husk with a hulling machine, followed by further drying until the moisture content reaches about 12-15%. The beans are then machine-sorted to remove impurities and graded by size.

After machine sorting, the coffee goes to hand-sorting warehouses, where workers pick out defective beans one by one. Only after two to three rounds of hand-sorting are the beans packed into burlap bags.

Of course, accidents can happen.

During hulling, bean temperatures can rise to 30-60°C, which completely destroys the parchment and can even trigger germination. Wet hulling can also lead to higher rates of defects such as moldy beans than washed and natural methods, because the skin is removed during processing and the beans are exposed directly to air. This is the distinctive method that creates Sumatra Mandheling's unique flavor. In addition, the removed skin and pulp can be fermented into fertilizer. When plantations use such ecological fertilizer, they can earn extra points when applying for organic coffee plantation certification.

Key Point: The biggest difference between wet hulling and conventional processing is that wet hulling dries the coffee beans after removing the outer husk, while conventional methods dry the beans first and remove the husk afterward.

FrontStreet Coffee Recommendation

To taste the wet-hulled style at its best, FrontStreet's PWN Golden Mandheling is the highest grade available. PWN buys only high-quality Mandheling green beans, then subjects them to one machine pass plus hand-sorting to pick out full, unblemished beans, and everything it releases is specialty grade. Golden Mandheling is the company's flagship: the beans are uniform and full, large and bright with a low defect rate, and after a medium-dark roast they carry a rich roasted aroma. Brewed as black coffee they have a clean mouthfeel and a full body, ideal for anyone who dislikes acidic coffee.

Pour-over shows Golden Mandheling at its best. Use 87-88°C water, 15g of coffee, a 1:15 ratio, and a coarse-sugar grind, then pour in three stages to better express the coffee's full body and caramel sweetness. The first pour of 30ml wets all the grounds for degassing; the second pour of 100ml flushes out the golden crema and lifts the bed; the final pour is a gentle 95ml down the center, which raises sweetness and reveals the overall full body with caramel sweetness and chocolate and nut flavors.

If you want this mellow character on an espresso machine, FrontStreet's Classic Blend is its most frequently repurchased espresso. It layers a medium-dark-roasted Mandheling over the creamy, nutty notes of Brazilian coffee, foregrounding butter, roasted chestnut, and caramel; the Mandheling not only lifts the body but adds sandalwood, herbal, and spice notes. A small amount of Robusta rounds out the crema, making latte art and layered Dirty drinks easy.