What is Wet Hulling Process: Indonesia Mandheling Coffee Bean Wet Hulling Method, Process Characteristics, and Flavor Description

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What is Wet Hulling?

Wet hulling is a coffee bean processing method, specifically used for Indonesian coffee beans. Coffee bean processing methods are actually related to local climate conditions. Indonesia uses this unique coffee processing method entirely because the local weather is predominantly rainy with constant typhoons, making it impossible to achieve the good weather required for sun-drying. Additionally, the local economy isn't strong enough to use the more expensive washed method. Indonesia remains hot and humid year-round with insufficient sunlight, and humidity consistently ranges between 70-90%. Therefore, relying purely on natural sun-drying is obviously unrealistic. For the ever-changing weather of Sumatra island, even using the washed processing method makes it difficult to find a full week of sunny weather for drying. Thus, wet hulling emerged as a solution. It accidentally became a unique processing method in the world and created the distinctive herbal, rich, nutty, and pine flavors of Indonesian Mandheling coffee.

FrontStreet Coffee's Indonesian Mandheling coffee beans have always been everyone's favorite, especially the single-origin Golden Mandheling coffee. Some people may not like the taste of Mandheling coffee, but friends who enjoy this texture will fall in love at first sip. Mandheling coffee represents Asian coffee with distinct pine, herbal, and nutty caramel flavors, some even saying it tastes remarkably like traditional Chinese medicine. However, Mandheling coffee boasts the richest body among all coffees in the world.

Mandheling Origins and Varieties

Mandheling is also known as "Sumatra coffee." Most coffee from northern Sumatra is Gayo, primarily of the Ateng variety. The Tawar Lake area in the northern part can be called Aceh coffee or Tawar Lake coffee. The Lintong and Lake Toba regions in southern Sumatra can be called Mandheling. The Lintong area is actually the Mandheling producing region. Mandheling is produced from the mountainous areas surrounding Lake Toba. This lake is located north of Medan, the capital of Sumatra island, and is a high-altitude freshwater lake with an average elevation of about 900 meters. The mysterious and unique natural environment of Sumatra gives Mandheling coffee its characteristics: rich body, intense flavor, with subtle chocolate and herbal notes.

Mandheling is also known as "Sumatra coffee." The Tawar Lake in the northern part can be called Aceh coffee or Tawar Lake coffee, while the Lintong and Lake Toba areas can be called Mandheling. FrontStreet Coffee offers two types of Mandheling coffee: the Indonesian Mandheling from our daily selection series and the single-origin Golden Mandheling coffee.

Lintong Mandheling

Lintong Mandheling is produced in the Lintong mountainous area of north-central Sumatra, near Lake Toba. Lintong Mandheling is the regular version of Mandheling. Lintong Mandheling also uses the conventional wet hulling method, which creates its characteristics of low acidity and high body. FrontStreet Coffee's Indonesian Mandheling from our daily selection comes from Lintong.

Golden Mandheling

The green bean specifications for Golden Mandheling are 18 screen or larger, with fewer than 3 defective beans (in a 300g green bean sample), belonging to the highest grade G1 level. The color is dark green, and the beans are uniform flat beans. After strict screening, FrontStreet Coffee found that Golden Mandheling not only lacks the distinctive earthy impurities of regular Mandheling but also tastes cleaner and brighter, with more intense sweetness. FrontStreet Coffee's Golden Mandheling comes from PWN company. Golden Mandheling is actually produced from Mandheling acquired locally in Indonesia by Pwani Coffee Company, which then registered the name Golden Mandheling. Therefore, only the Mandheling produced by this company is authentic Golden Mandheling.

Golden Mandheling differs from regular Mandheling not just in size, but its production process and regional selection already determine different flavor profiles. FrontStreet Coffee believes that for professional-level coffee connoisseurs and taste-sensitive coffee friends, if these two coffees are tasted side by side, the comparison will be very obvious. The sweetness, cleanliness, body, and wild spice flavors of Golden Mandheling are superior to G1, which is one reason why Golden Mandheling is much more expensive than G1.

Wet Hulling Process

The difference between Mandheling coffee beans' wet hulling method and the washed processing method is: the washed processing method retains the pectin for fermentation, then uses clean water to wash away residual pectin before direct sun-drying, and the coffee beans are stored with parchment intact. In contrast, wet hulling uses washed processing for fermentation, then after semi-drying, removes the parchment by machine before final drying. The coffee beans enter storage "naked." The body of Mandheling coffee ranks among the top in specialty coffee, with heavy body and low acidity as its characteristics. The smoothness and sweetness of dark chocolate and caramel provide a very long-lasting aftertaste, with complex flavor layers.

Specific Steps of Mandheling Coffee Bean Wet Hulling:

1. Coffee farmers first harvest ripe coffee cherries and place them in water tanks, using flotation to remove debris and unripe coffee cherries.

   

2. Then use a pulping machine to remove the pulp and skin, retaining the parchment and pectin for brief fermentation to decompose the pectin.

3. The washed green coffee beans undergo drying treatment, placing the parchment-protected coffee beans under direct sunlight for 1-2 days to reduce the moisture content to 30%-50%.

   

4. Then use machines to remove the pectin and parchment layer. The coffee beans with the inner parchment removed undergo another drying process for 2-4 days, reducing moisture content to about 12-13% to complete the processing.

Teacher Han Huaizong once described the flavor characteristics of wet-hulled coffee beans in his book: "This is also a rare processing method in the world, which accidentally created Mandheling's special low-acidity, thick, and mellow aromatic flavor."

Although wet hulling creates the unique flavor of Mandheling coffee, one situation that occurs with this method is that when semi-hard, semi-soft moist green beans have their pectin and parchment layers removed by machine, they are easily crushed. The injured beans crack open in a cloven hoof shape, commonly known as "goat hoof beans." FrontStreet Coffee considers this a very distinctive characteristic of Mandheling coffee beans, not classified as defective beans.

Mandheling Coffee Bean Varieties

Mandheling coffee specifically refers to Arabica coffee beans grown on Sumatra island in Indonesia, with varieties mostly being Timtim or Ateng. Timtim is Timor, an Arabica variety with Robusta bloodlines, while Ateng is Catimor, a hybrid of Caturra and Timor.

Both varieties have Arabica and Robusta genes. The Arabica genes bring better coffee flavor, while Robusta provides better pest and disease resistance, suitable for growing in Indonesia's hot and humid climate environment.

One drawback of Robusta genes is that the flavor itself is relatively rough and not very palatable. Even though Mandheling varieties are mainly Arabica-based, they cannot completely eliminate the dull notes from Robusta, combined with the "hardcore" operations of Indonesia's unique coffee processing method.

Therefore, regardless of which type of Mandheling coffee bean, they all display rich flavors of herbal, spice, and cocoa notes, with low acidity and high body - these unique Sumatra regional flavor characteristics.

Careful observers might notice the "cloven hoof shape" characteristic of Mandheling coffee beans. FrontStreet Coffee has also noted their common bean appearance feature of "cloven hoof shape." This occurs because when semi-hard, semi-soft moist green beans have their pectin and parchment layers removed by machine, they are easily crushed, causing the beans to crack open in a cloven hoof shape, commonly known as "goat hoof beans." The "cloven hoof shape" is a very distinctive characteristic of Mandheling coffee beans, so it's not considered a defect.

FrontStreet Coffee's Mandheling Brewing Parameters:

FrontStreet Coffee uses the KONO dripper for brewing Mandheling coffee. The KONO's ribs stop at less than half the height of the dripper. This design is actually to ensure the filter fits tightly against the dripper wall after wetting, restricting airflow to increase the water absorption time of coffee particles. This results in more uniform extraction overall and enhances the rich body.

KONO dripper, 88°C water temperature, 1:15 coffee-to-water ratio, 15g coffee grounds, grind size (75% pass-through rate on #20 standard sieve), three-stage extraction.

Using segmented extraction, bloom with twice the amount of water as coffee grounds - that is, 30g of water for 30 seconds. The blooming process is necessary to allow the coffee grounds to release internal carbon dioxide gas, making the later extraction more stable. With small circular water flow, pour to 125g for segmentation, then continue pouring to 225g and stop. Wait until the water in the dripper finishes dripping, then remove the dripper. Time from the start of pouring: extraction time is 2'00". Then pick up the entire cup of coffee, shake it well, and pour into cups for tasting.

Lintong Mandheling Coffee Flavor: Herbal, chocolate, caramel, overall quite balanced.

Golden Mandheling Coffee Flavor: Nuts, spices, herbal plants, licorice, chocolate, caramel.

FrontStreet Coffee Brewing Suggestions:

To brew a delicious cup of coffee, FrontStreet Coffee believes that any brewing method requires fresh coffee beans. FrontStreet Coffee has always maintained that the freshness of coffee beans greatly affects coffee flavor. Therefore, FrontStreet Coffee ships coffee beans roasted within 5 days. FrontStreet Coffee's roasting philosophy is "freshly roasted good coffee," ensuring that every customer who orders receives the freshest coffee. The coffee resting period is about 4-7 days, so when customers receive it, it's at peak flavor.

For friends who need ground coffee, FrontStreet Coffee kindly reminds: if coffee beans are ground in advance, there's no need for further resting, because during transportation, the pressure from carbon dioxide inside the packaging also helps round out the coffee flavor, so you can brew a cup immediately upon receiving the ground coffee. However, ground coffee needs to be brewed promptly, because ground coffee oxidizes quickly when exposed to air, meaning the coffee flavor will dissipate relatively quickly, and the coffee won't taste as good. Therefore, FrontStreet Coffee suggests purchasing whole beans and grinding fresh before brewing to better appreciate the coffee's flavor.

There are many coffee bean processing methods, but all are built upon the foundation of washing and sun-drying. At the same time, different processing methods result in different flavors. With the advancement of specialty coffee, many processing methods have emerged, such as honey processing, anaerobic processing, etc. FrontStreet Coffee has acquired coffee beans with these processing methods, such as Costa Rican honey-processed Mirasu Geisha coffee, the Mozart coffee from the Musician series; Colombian anaerobic-processed Huayueye coffee and Rose Valley coffee, etc. FrontStreet Coffee has over fifty different regional coffee beans, fully satisfying coffee friends' exploration and understanding of coffee.

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Important Notice :

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