What's the Difference Between Wet Hulling and Washed Methods? Flavor Characteristics of Indonesian Coffee Beans Processed with Wet Hulling

What Makes Wet Hulling Special?

As the name suggests, wet hulling refers to removing a certain substance from coffee beans before they are dried, and that substance is the parchment, also known as the endocarp. Unlike other coffee processing methods where the parchment is removed just before export, the special feature of wet hulling is that the parchment is removed during the processing stage.

Why Does Indonesia Use Wet Hulling to Process Coffee Beans?

Indonesia experiences consistently high temperatures and humidity year-round, with insufficient prolonged sunlight and humidity typically ranging between 70-90%. Therefore, relying solely on natural sun-drying methods is clearly impractical. For the ever-changing weather of Sumatra Island, even using washed processing for coffee beans makes it difficult to find a full week of sunny weather for drying. Thus, wet hulling emerged as a solution. After following the washed processing steps, the parchment-covered coffee beans are exposed to intense sunlight for 1-2 days until the moisture content reaches 30-50%, then the parchment is removed for sun-drying. This accelerates the drying process of coffee beans and significantly shortens the drying duration.

Wet Hulling Process

① After harvesting fresh coffee cherries, they undergo flotation processing. Some low-density cherries will float on the water surface - these are considered inferior coffee fruits.

② Remove the exocarp and pulp from the coffee cherries, then place them in clean water pools for fermentation for 12-36 hours (depending on conditions). The purpose is to decompose and remove the mucilage layer attached to the coffee beans. Up to this point, the process follows washed processing methods.

③ Place the parchment-covered coffee beans under intense sunlight for 1-2 days. If both days are sunny, the moisture content of the coffee beans will reach approximately 30-50%. At this stage, the coffee beans are in a semi-soft, semi-hard state.

④ Then use a hulling machine to remove the parchment from the coffee beans. After about two more days of intense sun exposure, the moisture content can reach 12%. This processing method significantly reduces processing time. For Indonesia's unpredictable weather, wet hulling can better ensure the completion of coffee processing.

The Flavor of Mandheling

Mandheling coffee is easily recognizable both in terms of flavor and bean appearance. Because wet hulling removes the parchment from coffee beans while they're still in a semi-soft, semi-hard state, the beans tend to crack under intense sun-drying, forming "hoof-shaped" beans. Therefore, they are also known as hoof beans, not considered defective beans.

Additionally, because wet hulling significantly shortens the drying time, the acidity of coffee beans is greatly reduced, body is markedly increased, with distinct caramel aromas and slight herbal fresh notes.

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