What are Indonesian Wet Hulling Coffee Beans? What Flavor Characteristics Do Wet Hulled Coffee Have?

The wide-ranging coffee regions of different countries, their varied growing environments and other factors all leave their mark on the flavor of a coffee.

Asia spans vast land and hosts many coffee varieties across its growing regions. The most famous include Indonesia, where coffee is known for its distinctive smoky sensation, herbal and spicy notes. Then there are beans from Vietnam, with clear fruit flavors and a high body; Vietnam mainly produces Robusta, a variety that is predominantly bitter with somewhat less aroma.

Of course, there are many lesser-known but promising regions producing excellent coffee. Papua New Guinea offers juicy acidity reminiscent of bayberries, noticeable sweetness and unique spicy flavors. The Philippines, Thailand, Fiji, Bali and other locations are all coffee regions with flavors of their own.

Coffee from several major Indonesian islands is well known, among them Sumatra, Java and Sulawesi.

Sumatran Mandheling Coffee

The famous beans of Sumatra — Mandheling — are the most familiar to everyone. Besides climate and geography, the special post-harvest processing method, wet-hulling, is one of the key reasons Mandheling tastes the way it does. Put simply, wet-hulling means removing the parchment while the beans are only halfway through drying, at a moisture content as high as 30%–50%, and then letting them continue drying to solve the problem of overly long drying times — completing the process in just four days.

The Wet-Hulling Processing Method

Wet-hulling is Indonesia's traditional processing method. After the cherries are pulped, they are washed in clean water to remove impurities and left to ferment in a sealed environment for 12–24 hours. The parchment beans are then hulled directly while still holding a high moisture content, and the green coffee is dried straight away until that moisture stabilizes. Wet-hulling carries risks, but when done well it can boost both body and cleanliness at once, setting it apart from the herbal flavors typical of Indonesian beans. They also have a secret, and it lies in their dry mill. Traditional Aceh coffee is mostly exported from the port of Medan, so the dry mills are all set up in Medan. After processing in Aceh, the coffee often has to be sent to Medan's warehouses for final processing and packing. But Medan's climate is consistently hot and humid — the enemy of coffee. Under those conditions for just a few days, the quality and lifespan of the coffee drop sharply.

Quality Characteristics of Mandheling

A high proportion of defective beans is a common problem with Mandheling, with extremely high rates of insect damage and partial acidity. In our experience, even green beans marked G1 grade still carry a great many defects. Only batches at Golden Mandheling grade or above, or those specially hand-selected, meet specialty coffee standards.

High-quality Mandheling should have a "herbal, licorice" aroma, with some acidity that must not be too strong. In particularly fine regions it can even carry caramel-like sweetness, with high body being its greatest trait. In roasting, controlling and retaining good body without triggering acidity and bitterness is something roasters have to manage. Common undesirable flavors in Mandheling include earthy notes from improper processing, complex and unclean flavors caused by defective beans, and bitterness or sharp acidity from improper roasting.

FrontStreet Coffee's Tiger Mandheling is very clean in both flavor and texture, with good caramel sweetness and cocoa notes.

Brewing Recommendations

FrontStreet Coffee's recommended brewing parameters:

KONO / 88°C / 1:14 / Time: one minute fifty seconds.

FrontStreet Coffee Recommendation

Wet-hulling is what gives Sumatra its dark, earthy-sweet personality, and FrontStreet's Lindong Mandheling is a perfect introduction to that style. From the Lintong area of Sumatra, it is an Indonesian G1-grade lot processed with the wet-hulling method and roasted deep. That combination pushes forward the charred sweetness of Mandheling — black sugar, spice, herbs, nuts and dark chocolate — with a rich, thick, low-acid cup. It suits pour-over, a moka pot or a clever dripper, and doubles as a practice bean for beginners.

If you want the cleanest possible expression of the same method, step up to FrontStreet's PWN Golden Mandheling. PWN's strict grading on density, size, shape and color, followed by machine screening and hand-sorting, keeps the beans even, plump and translucent and tames the muddy, grassy edge that plagues lesser Mandheling. Medium-deep roasted, it pours out sandalwood, herbs, spice, roasted hazelnut, caramel and dark chocolate with a clean, concentrated body — a good everyday cup and an even better gift.