Wet-Hulled Mandheling Coffee Bean Flavor Profile and Processing Method Differences

Introduction

Anyone who has tasted Mandheling coffee will be amazed by its herbal aroma. Most Mandheling coffee undergoes relatively deep roasting, which reduces the acidity in the coffee and creates a richer, more caramelized flavor with herbal, spicy, and pine notes. FrontStreet Coffee believes that Mandheling's unique taste primarily stems from the wet-hulling method used by local processors.

What Makes Wet-Hulling Special?

The name itself provides clues - "wet-hulling" refers to removing a certain layer from the coffee beans before they are fully dried. This layer is the parchment, also known as the endocarp. Other coffee processing methods typically remove the parchment just before export, but the special feature of wet-hulling is that the parchment is removed during the processing stage itself.

Why Does Indonesia Use Wet-Hulling for Coffee Processing?

Indonesia experiences year-round high temperatures and humidity, with insufficient sunlight for extended periods. Humidity typically ranges between 70-90%, making pure sun-drying clearly impractical. For the weather-volatile Sumatra island, even using the washed method for coffee processing makes it difficult to secure a week of sunny weather for drying. Therefore, the wet-hulling method emerged as a solution. After following the initial 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, which accelerates the drying process and significantly shortens the drying time.

Wet-Hulling Process

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

② The outer skin and pulp of the coffee cherries are removed, then placed in clean water tanks 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 standard washed processing methods.

③ The parchment-covered coffee beans are exposed to intense sunlight for 1-2 days. If two consecutive days are sunny, the moisture content of the coffee beans will be between 30-50%. At this stage, the coffee beans are in a semi-soft, semi-hard state.

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

The Taste of Mandheling

Mandheling coffee is easily recognizable both in flavor and bean appearance. Because wet-hulling removes the parchment from coffee beans when they are still in a semi-soft, semi-hard state, the intense sun-drying process causes the beans to crack easily, forming a "hoof" shape. These are known as "hoof beans" and are not considered defective beans. Additionally, because wet-hulling significantly shortens drying time, the acidity of the coffee beans is greatly reduced while body is notably enhanced, with prominent caramel aromas and subtle herbal freshness.

Although wet-hulling indeed creates Mandheling's unique herbal and woody aromas, it also results in a higher defect rate in green beans. Dark roasting can perfectly mask this flaw. Furthermore, Mandheling's fame originated from early discovery by the Japanese, who preferred Japanese-style dark roasting based on their taste preferences. This is why most Mandheling coffee is roasted so darkly. FrontStreet Coffee wants everyone to experience the classic Mandheling flavor, so the two Mandheling varieties sold regularly by FrontStreet Coffee both use medium-dark roasting, including the Lintong region Mandheling daily beans and the Aceh region PWN Golden Mandheling coffee beans.

Indonesian green bean grading is primarily based on the number of defective beans, with size as a secondary factor. General quality requirements include no live insects, no moldy or rotten beans, maximum moisture content of 12.5%, and impurity rate less than 0.5%. Based on defect rate, beans are classified into six grades, with the highest grade G1 requiring fewer than 11 defective beans in a 300g sample. The Lintong Mandheling coffee in FrontStreet Coffee's daily bean series is G1 grade, processed using the wet-hulling method, representing the conventional Indonesian Mandheling flavor profile.

The PWN company, which goes to extremes in selection, purchases Mandheling green beans of 18 screen size or larger. With fewer than 3 defective beans in a 300g sample, these achieve G1 grade - the highest grade for Indonesian green beans. Subsequently, they undergo strict standards including one machine selection plus three manual defect selections to ensure uniform shape and size of Mandheling coffee beans. Additionally, before packaging, PWN places the green beans in machines for density-based color sorting, ensuring Golden Mandheling beans have uniform and bright coloration.

For coffees with rich body and distinct regional characteristics like Golden Mandheling, FrontStreet Coffee recommends extraction and tasting through pour-over black coffee to better appreciate the coffee's aroma. The coffee beans shipped by FrontStreet Coffee are freshly roasted within 5 days, ensuring they arrive at optimal freshness, adding more flavor layers to our cups.

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