How Should Golden Mandheling Coffee Be Roasted and Hand-Brewed?

Golden Mandheling is a Sumatra coffee known for strict hand sorting and a mellow cup. Front Street's PWN lot comes from the Lintong region at 1,100 to 1,600 meters, wet-hulled and made up of Timtim and Ateng varieties. Its flavor runs to baked toast, nuts, caramel, herbs, and chocolate, with low acidity and a long finish.

The article compares light, medium-dark, and dark roast results in pour-over, then gives five brewing methods used in Front Street stores: pour-over, volcano brew, AeroPress, siphon, and French press, each with water temperature, coffee-to-water ratio, grind size, and time. Dark roasting brings out both lingering bitterness and an elegant sweetness, so processing and roast level together decide the cup.

Mandheling is the most representative coffee of Sumatra, Indonesia, and Golden Mandheling is especially renowned for its strict hand-sorting standards and mellow flavor. This article starts with Front Street Coffee's PWN Golden Mandheling, outlining its producing region, varieties, and wet-hulling process, and compares the performance differences of light, medium-dark, and dark roast levels in pour-over brewing. It also provides five brewing methods commonly used in Front Street stores—pour-over, volcano brew, AeroPress, siphon, and French press—including water temperature, coffee-to-water ratio, grind size, and time parameters, helping coffee enthusiasts reproduce Golden Mandheling's spice, nut, caramel, and chocolate notes at home and find a brewing method that suits them.

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Mandheling originates from the island of Sumatra in Indonesia, Asia, and is therefore also called Sumatra coffee. Its main producing regions include Java, Sulawesi, and Sumatra, with Sumatra-produced Mandheling being the most famous.

Among the traditional Arabica specialty coffees produced in northern Sumatra, the highest-quality ones enter the market under the names Lintong and Mandheling. Strictly speaking, Lintong refers to coffee grown in a small area on the southwest side of Lake Toba in the Lintong administrative region. Local coffee farms are scattered, located on high, uneven, fern-covered clay plateaus. Lintong coffee is not shade-grown and does not use chemicals, and is almost entirely held by smallholder farmers.

Front Street Coffee — Indonesia Sumatra Lintong Mandheling

Region: Indonesia Sumatra, Lintong region

Altitude: 1100-1600m

Processing method: Wet-hulled

Varieties: Timtim, Ateng

Flavor description: baked toast, nuts, caramel, herbs, chocolate

Front Street Coffee believes that Mandheling has rich aromatic layers, a full and mellow mouthfeel, low acidity, and a long finish. When dark-roasted, one can feel both the lingering bitterness and enjoy an elegant sweetness, experiencing its distinctive deep aroma through both smell and taste.

Based on our understanding of Mandheling, Front Street's roasters aim to present its flavor to the greatest extent, preserving Mandheling's own character while also accommodating most people's taste preferences. Every specialty coffee shop has its own personality, and Front Street hopes to incorporate our unique understanding of coffee, presenting the best Mandheling to guests while retaining Front Street Coffee's characteristics. Front Street Coffee currently sells two Mandheling coffee beans: one is the Lintong region Mandheling mentioned above, and the other is Golden Mandheling from the PWN company in the Gayo Mountain area of Aceh.

Front Street Coffee — Indonesia Sumatra Front Street PWN Golden Mandheling coffee beans

Region: Indonesia Sumatra, Aceh Gayo Mountain

Altitude: 1100-1600m

Processing method: Wet-hulled

Variety: Ateng

Flavor description: spices, nuts, pine, caramel, herbs, chocolate

The difference between the two is that Front Street PWN Golden Mandheling undergoes at least three rounds of purely manual sorting after harvesting and drying, ensuring that the green bean specification reaches 18 mesh or above, with fewer than 3 defective beans in a 300g green bean sample, belonging to the highest grade G1. PWN Golden Mandheling has a darker green color, neat bean shape, and is a flat bean.

What are the differences between Mandheling coffee beans at different roast levels?

To this end, Front Street Coffee tested light roast, medium-dark roast, and dark roast Mandheling coffee beans using drip extraction (pour-over)～one serving, with grind size and water temperature slightly adjusted according to roast level.

1. Light roast: No. 20 sieve screen pass rate 80%, water temperature 90°C, coffee-to-water ratio 1:15

2. Medium-dark roast: No. 20 sieve screen pass rate 75%, water temperature 88°C, coffee-to-water ratio 1:15

3. Dark roast: No. 20 sieve screen pass rate 70%, water temperature 86°C, coffee-to-water ratio 1:15

The test results are as follows:

1. Light roast: At this roast level, Mandheling has heavier fruit acidity with a slight bitterness. The fruit acidity is pronounced but comfortable on entry, with a mouth-watering sensation on both sides of the mouth, and average smoothness.

2. Medium-dark roast: Very good balance, rich and mellow, with more pronounced bitterness. Chocolate notes and slight sweetness are more prominent, licorice aroma is obvious, fruit acidity is weaker, smoothness is better than light roast, aroma is strong, and the fruit acidity sensation is noticeably enhanced.

3. Dark roast: Almost no acidity, very heavy bitterness. If direct-fire roasting is used and operated improperly, a burnt taste may also occur.

All coffee beans sold by Front Street Coffee are freshly roasted and shipped within 5 days after roasting～the optimal flavor period for freshly roasted coffee beans is 30-35 days after roasting.

The darker the roast level, the more carbon dioxide is produced inside the coffee beans. After roasting is completed, the beans are rich in carbon dioxide, so there is no need to rush to drink them. You can first rest the beans for 3-5 days (counting from the roast date), allowing the coffee beans to release some carbon dioxide on their own in the original packaging, reducing uneven extraction caused by excessive bubbles during brewing.

Mandheling coffee bean processing method — Sumatra wet-hulled process

March to May and September to December each year are the seasons for harvesting Mandheling in Sumatra. Nowadays, most coffee farmers also only harvest fully red coffee cherries. After collecting the coffee cherries in the morning, they remove the skin and pulp in the afternoon. Sumatra's natural environment is excellent, and most of the water used is mountain spring water.

1. After peeling the coffee fruit, place the parchment beans into a large bucket or tank filled with water, and remove the defective parchment beans floating on the surface.

2. Briefly wash the dense parchment beans that sink to the bottom, take them out and put them into a bucket or plastic bag for brief dry fermentation, which means allowing the pectin sugars on the parchment surface to ferment and enhance flavor. Basically, the longer the fermentation time, the heavier the acidity. Fermentation time varies from person to person, generally only a few short hours, but some estates omit the dry fermentation stage and directly sun-dry the parchment beans, which can suppress acidity and increase the viscous mouthfeel. To allow the pectin sugars to fully ferment and increase flavor, the fermentation time is usually between 12-36 hours, depending on the specific situation.

3. Sun-dry the parchment beans for one to two days, until the bean moisture content reaches 30%-50%. The beans are still half-hard and half-soft. Use a huller to scrape off the parchment and then sun-dry again to accelerate the drying process. After about two days, the moisture content reaches 12%-13%, and the coffee beans are collected into woven bags, usually 40 kg and 80 kg per bag, and sent to a coffee processing factory for hulling. All done, about four days in total.

The hulling process uses a huller to grind off the bean husk, then sun-dry again until the moisture content reaches about 12%-15%. Then, the coffee beans are sent for machine sorting to remove various impurities, and then classified by particle size. Of course, accidents can also happen. During the hulling process, the temperature of the coffee beans rises to 30-60°C, and the parchment is completely destroyed, which may very likely trigger germination of the beans. The wet-hulled method also results in beans being directly exposed to air because the fruit skin is scraped off during production, so moldy beans and other defective beans are far more common than in washed and natural methods. Mold brings good flavor because coffee beans have four layers of protection: fruit skin, pectin, parchment, and silver skin.

In the washed method, only the first two layers are removed, retaining the parchment and silver skin for sun-drying. The wet-hulled method, however, scrapes off the third and fourth protective layers midway, meaning the beans are naked and receive a sunbath. This is why Sumatra green beans have a blue-green color. Although the wet-hulled method shortens drying time, the chance of contamination by mold, fungi, and yeast also increases greatly. Interestingly, contamination is not necessarily a bad thing; it depends on the strain of bacteria. Dr. Martha Taniwaki of the Brazilian Food Technology Institute once tried infecting coffee beans with different strains, and surprisingly produced different flavors, including spoilage, rancid, musty, woody, iodine, caramel, chocolate, and floral notes.

The academic community believes that the woody, grass jelly, earthy, banana, and spice flavors of Sumatra coffee are likely created by mold. Roastery supervisors also often report to academia that some mold-infected coffee beans taste better after being cleaned, while others are difficult to drink. The key is related to the strain of bacteria. Perhaps it is possible to suppress bad mold and introduce good mold, control wild yeast, and cultivate elegant yeast in the same way. But which molds help enhance coffee flavor? Which are bad bacteria? Further research is still needed.

Goat hoof beans are the "identity card" of Mandheling coffee beans!

The wet-hulled method may trigger the germination mechanism of green beans, thereby affecting flavor. Because coffee beans that have lost their four protective layers are in a naked state, they are far more likely to trigger germination than washed beans that have only lost two protective layers, meaning they activate the metabolism of sugars, proteins, and fats, and these components are coffee aroma precursors. In addition, the friction generated during the hulling process raises the bean temperature to 30°C-60°C, which also favors germination and mold growth.

Moreover, the half-hard, half-soft moist green beans are easily crushed by mechanical force when the parchment is scraped off, and the beans are prone to cracking into a goat hoof shape. This is why Sumatra has a relatively high proportion of goat hoof beans. But whether goat hoof beans are good or bad still has no definitive conclusion. The key to control is keeping the equipment and beans clean. Once hulled, drying must be fast to produce a mellow, low-acid yet sweet Sumatra flavor; if control is improper, it may produce a dull Sumatra, or even a moldy, earthy taste. If you prefer stronger acidity, Aceh can also undergo washed processing, depending on customer demand.

Summary of wet-hulled processing flavor characteristics

To summarize the flavor of wet-hulled coffee, setting aside those subtle differences. We generally believe that wet-hulled beans have earthy, smoky, and chocolate notes. They are mellow yet seem quite dull. The low acidity comes from a shorter, weaker fermentation process and a longer drying time. If you forgot about wet-hulled fermentation, go back and take a look.

As for the earthy and herbal flavors of wet-hulled beans, opinions vary widely. Some say this is related to the bean varieties selected in wet-hulled producing regions (Tim system & Catimor system: with Robusta lineage), some say it is the result of organic interaction between green beans and the external environment, and some even say it is because there are too many defective beans!

There are many sources of defective beans in the wet-hulled method. First, natural defects present from the coffee fruit stage are certainly unavoidable. Another contributor to defects is the hulling part, as well as corrosion during the transportation of wet parchment beans, damage to exposed green beans from sunlight and moisture, and irregular weather causing uneven drying speeds, which also detracts from flavor. This is why Mandheling requires so many rounds of hand sorting.

Finally, Front Street Coffee summarizes the characteristics of various green bean processing methods～

Acidity: washed > semi-washed > honey > wet-hulled > natural

Sweetness: natural > honey > wet-hulled > semi-washed > washed

Production risk: wet-hulled / natural > washed / honey > semi-washed

Equipment cost: washed / semi-washed > honey / wet-hulled > natural

Water usage: washed > semi-washed > honey / wet-hulled

How to brew Mandheling coffee beans?

Different equipment and different brewing methods will also produce different mouthfeels. Next, Front Street will use the store's PWN Golden Mandheling coffee beans as an example, using four different brewing methods to compare and analyze their flavor characteristics.

【Pour-over】

Flavor: varied layers, clean, balanced, long-lasting caramel sweetness in the finish

1. Equipment selection: Hario V60

2. Water temperature: 88°C

3. Grind size: medium-coarse (standard No. 20 sieve pass rate 70%)

4. Roast level: medium-dark roast

5. Blooming time: 25 seconds

Specific method: 【three-pour interruption】pour-over Mandheling, 15g coffee, small Fuji ghost tooth grinder setting 4, V60 dripper, 88-89°C water temperature. First pour 30g water, bloom for 25s, pour until 104g and stop, wait for the water level in the coffee bed to drop to half before pouring again, slowly pour until 220g, discard the last 5g. Coffee-to-water ratio 1:15, extraction time about 2:00.

Mandheling can also be extracted using the volcano brew method, with a flannel or Kono dripper!

Specific method: high-temperature extraction, water temperature 90-92°C. In the front stage, pour with a small stream at a position the size of a one-yuan coin, stop, bloom, stop, bloom, keeping the coffee grounds in a blooming state. Blooming time 1:30, then finally extract quickly with a large stream. Total extraction time 2:30.

【AeroPress】

Front Street Coffee believes that Mandheling brewed with an AeroPress is characterized by a rich and complex flavor, prominent spice notes, and a fresh forest aroma.

1. Equipment selection: AeroPress

2. Water temperature: 85°C

3. Grind size: medium-coarse (standard No. 20 sieve pass rate 70%)

4. Roast level: medium-dark roast

5. Blooming time: 2 times, first 20 seconds, second 50 seconds

Specific method: Prepare the AeroPress for standard pressure. It is recommended to add 20g coffee grounds, coffee-to-water ratio 1:17. First pour 100g of 83°C hot water, stir three to five times to fully wet the coffee grounds, let sit for 20s, add the remaining hot water to 240g, let sit for 40s, stir for 5s, and at 1 minute 50 seconds attach the plunger and press down. Total time 2 minutes 5 seconds.

【Siphon】

Flavor: rounded, rich, prominent herbal and bitter notes, accompanied by prominent caramel sweetness

1. Equipment selection: Hario siphon

2. Water temperature: 90°C

3. Grind size: medium-coarse (standard No. 20 sieve pass rate 70%)

4. Roast level: medium-dark roast

5. Blooming time: 30 seconds

Specific method: side-burn extraction. It is recommended to use 20g coffee for 2 servings, coffee-to-water ratio 1:12, water level mark 2. Use the late-add method: add the coffee after bubbles appear, stir 4-5 times, extract for about 30 seconds then turn off the heat. Finally, stir 2 times and wait for the coffee liquid to fall freely.

【French press】

Flavor: balanced, mellow, good body and oils, with a slight sweetness

1. Equipment selection: French press

2. Water temperature: 92°C

3. Grind size: medium-coarse (standard No. 20 sieve pass rate 70%)

4. Roast level: medium-dark roast

5. Blooming time: 2 minutes 30 seconds

Specific method: 20g coffee beans, pour hot water (about 92-93°C) into the French press up to the 300ml mark on the body, start timing, cover the French press with the lid with the filter resting at the highest position, wait 2 and a half minutes. Press the filter all the way down.

Summary: The 【pour-over】 and 【AeroPress】 methods are recommended to showcase the rich and sweet flavor of Front Street PWN Golden Mandheling. The siphon and French press methods are more likely to cause over-extraction, and once over-extracted, only sour and bitter flavors can be tasted.

The above content is compiled by CoffeeHunters, a coffee news website.