Is Mandheling Coffee Arabica or Robusta?

Mandheling is an Arabica coffee from northern Sumatra, Indonesia, not Robusta. The name refers to the Mandheling people rather than a botanical variety, and the lots are built mostly from Timtim and Ateng grown at 1,100 to 1,600 meters around the Lintong region southwest of Lake Toba. The cup shows baked toast, nuts, caramel, herbs, and chocolate.

Its signature comes largely from the wet-hulled coffee bean process, known locally as giling basah, which strips the parchment while the bean is still moist and produces the heavy body and low acidity Sumatra is known for. Lintong and PWN Golden Mandheling differ noticeably in cup, and roast level plus method change extraction: pour-over, AeroPress, siphon, and French press each pull out different aspects.

Mandheling coffee is a representative coffee of Sumatra, Indonesia, but many people are not clear about its variety classification, processing method, and brewing method. This article starts from the production area, variety, and wet-hulling process, and analyzes in detail whether Mandheling belongs to Robusta or Arabica, and compares the differences between two Mandheling products from Front Street Coffee—Lintong Mandheling and PWN Golden Mandheling. At the same time, through cupping comparisons of light, medium-dark, and dark roast levels, as well as practical parameters for four brewing methods—pour-over, AeroPress, siphon, and French press—it helps coffee enthusiasts fully understand the flavor characteristics and extraction key points of Mandheling.

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Mandheling is a coffee produced in Sumatra, Indonesia, in Asia, so it is also called Sumatra coffee. Indonesia's main coffee production areas include Java, Sulawesi, and Sumatra, among which Mandheling produced in Sumatra is the most famous.

Among the refined traditional Arabica coffees produced in northern Sumatra, the highest-quality ones enter the market under the two names Lintong and Mandheling. Strictly speaking, Lintong refers to coffee grown in a small area within the Lintong administrative region southwest of Lake Toba. These coffee-growing areas are scattered across a high-altitude, undulating clay plateau covered with fern vegetation. Lintong coffee is not shade-grown and does not use chemicals, and it is almost entirely managed by smallholders.

FrontStreet Coffee—Indonesia Sumatra Lintong Mandheling

Region: Indonesia Sumatra, Lintong region

Altitude: 1100-1600m

Processing method: wet-hulled

Variety: Timtim, Ateng

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

FrontStreet Coffee believes that Mandheling coffee has a rich aroma profile, a full and mellow body, and low acidity, making it very intriguing. When dark-roasted, one can feel both its lingering bitterness and its elegant sweetness, and through smell and taste one can simultaneously appreciate its unique brooding aroma.

Based on our understanding of Mandheling coffee, Front Street's roasters decided to present Mandheling's flavor as fully as possible, while preserving Mandheling's own style and making it suitable for most people's tastes. Every specialty coffee shop has its own characteristics. Front Street hopes to bring our unique understanding of coffee to show guests the best Mandheling while preserving the characteristics of FrontStreet Coffee. FrontStreet Coffee currently sells two kinds of Mandheling coffee beans. One is the Lintong-region Mandheling coffee beans mentioned above, and the other is Golden Mandheling coffee beans from the PWN company on Mount Gayo in Aceh.

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

Region: Indonesia Sumatra, Mount Gayo, Aceh

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 coffee beans undergo at least three rounds of hand sorting after harvest and drying to ensure that the bean size reaches 18 or above. Defective beans are fewer than 3 (in a 300g green bean sample), belonging to the highest grade, G1. PWN beans are darker green in color and have a neat, flat bean shape.

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

For this reason, FrontStreet Coffee tested light-roasted, medium-dark-roasted, and dark-roasted Mandheling coffee beans through drip extraction (pour-over)～

For one serving, the grind size and water temperature are slightly adjusted according to the roast level.

1. Light roast: 80% passing through a No. 20 national standard sieve, water temperature 90°C, water-to-coffee ratio 1:15

2. Medium-dark roast: 75% passing through a No. 20 national standard sieve, water temperature 88°C, water-to-coffee ratio 1:15

3. Dark roast: 70% passing through a No. 20 national standard sieve, 86°C, water-to-coffee ratio 1:15

The test results are as follows:

1. Light roast: Mandheling at this roast level has a relatively strong fruity acidity and is slightly bitter. The fruity acidity is obvious but comfortable on entry, with a salivation sensation on both sides of the mouth, and the smoothness is average.

2. Medium-dark roast: The balance is very good, aromatic and mellow, with a more obvious bitterness. The chocolatey and slight sweetness are more prominent, licorice aroma is obvious, fruity acidity is weak, smoothness is better than light roast, the aroma is strong, and the fruity acidity is noticeably enhanced.

3. Dark roast: Almost no acidity, very heavy bitterness. If direct-fire roasting is used and the roast is slightly improper, it will also produce a burnt taste.

All coffee beans sold by FrontStreet Coffee are freshly roasted and shipped within 5 days after roasting～The best flavor appreciation period for freshly roasted coffee beans is 30-35 days after roasting is completed.

The darker the roast level, the more carbon dioxide is produced inside the coffee beans. After roasting is completed, the coffee beans contain abundant carbon dioxide, so do not 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 part of the carbon dioxide on their own in the original packaging, reducing uneven extraction caused by too many carbon dioxide bubbles during the extraction process.

Mandheling coffee bean processing method—Sumatra wet-hulled method

March to May and September to December each year are the seasons for harvesting Mandheling in Sumatra. Now most coffee farmers also only harvest fully red coffee cherries. After collecting the coffee cherries in the morning, in the afternoon the coffee cherries are depulped and the fruit mucilage removed. Sumatra has a superior natural environment, and most of the water used is mountain spring water.

1. After the coffee fruit is depulped, 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, and carry out a brief dry fermentation, that is, allowing the pectin sugars on the surface of the parchment 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 hours, but some estates omit the dry fermentation stage and directly sun-dry the parchment beans, which can reduce acidity and increase the viscous mouthfeel, allowing 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% and the beans are still half-hard and half-soft. Use a huller to scrape off the parchment and then dry again to accelerate the drying process. After about two days, when the moisture content reaches 12%-13%, 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. Done, about four days in total.

The hulling process uses a huller to grind off the bean parchment, then dries again until the moisture content reaches about 12%-15%. Then, the coffee beans are sent for mechanical sorting to remove various impurities, and then classified by bean 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 directly contacting the air because the fruit skin is removed during processing, so moldy beans and other defective beans are far more common than in washed and natural methods. Mold brings good flavors 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, and then the beans are sun-dried. The wet-hulled method, however, scrapes off the third and fourth protective layers midway, that is, the naked body receives a sunbath, which is why Sumatra green beans have a blue-green color. Although the wet-hulled method shortens drying time, the chance of exposure to mold, fungi, and yeast also greatly increases. Interestingly, contamination is not necessarily a bad thing; it depends on the strain. Dr. Martha Taniwaki of Brazil's Institute of Food Technology once tried infecting coffee beans with different strains and unexpectedly produced different flavors, including putrid, rancid, moldy, woody, iodine, caramel, chocolate, and floral notes.

The academic community believes that the woody, grass jelly-like, earthy, banana, and spice flavors of Sumatra coffee should be created by mold. Roastery supervisors also often report to academia that some coffee beans infected with mold have better flavor after being thoroughly cleaned, while others are hard to drink, depending on the strain. Perhaps it is possible to inhibit bad molds and introduce good molds, control wild yeasts, and cultivate elegant yeasts in the same way. But which molds help enhance coffee flavor? Which are bad molds? 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, that is, activating 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, when the half-hard, half-soft moist green beans have their parchment removed, they are easily crushed by mechanical force, and the beans are easily wounded and split into a goat-hoof shape. This is why Sumatra has a higher proportion of goat-hoof beans. But whether goat-hoof beans are good or bad is still inconclusive. The key to control is keeping the equipment and beans clean. Once hulled, drying must be fast in order 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 the flavor characteristics of the wet-hulled processing method

To summarize the flavor of wet-hulled coffee, setting aside those minor differences. We generally believe that wet-hulled beans have earthy, smoky, and chocolate notes. They are mellow yet seem very subdued. 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 production areas using the wet-hulled method (Tim family & Catimor family: with Robusta lineage), some say it is the result of organic interactions between green beans and the external environment, and some even say it is because there are too many defective beans!

In the wet-hulled method, there are many sources of defective beans. First, natural defects that exist from the coffee fruit stage are certainly unavoidable. Another contributor to defects is the hulling stage, as well as corrosion during the transportation of wet parchment beans, damage to exposed green beans from sunlight and moisture, and another point: uneven drying speed caused by irregular weather also detracts from the flavor. This is why Mandheling requires so many rounds of hand sorting.

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

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

[Pour-over]

Flavor: layered and varied, clean, balanced, with a lingering caramel sweetness in the finish

1. Choice of equipment: Hario V60

2. Water temperature: 88°C

3. Grind size: medium-coarse (70% passing through a standard No. 20 sieve)

4. Roast level: medium-dark roast

5. Blooming time: 25 seconds

Specific method: [three-stage water break] pour-over Mandheling, 15g coffee, ground with a Fuji Ghost burr grinder at setting 4, V60 dripper, 88-89°C water temperature. First pour 30g water, bloom for 25s, pour until 104g water and stop, wait until the water level in the coffee bed drops to half before pouring again, pour slowly until 220g water, discard the last 5 grams, water-to-coffee ratio 1:15, extraction time about 2:00

Mandheling can also be extracted using the volcano pour, and flannel or Kono are also fine!

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

[AeroPress]

FrontStreet Coffee believes that Mandheling coffee brewed with an AeroPress has the characteristics of a rich and complex flavor, prominent spice notes, and the fresh fragrance of forest wood.

1. Choice of equipment: AeroPress

2. Water temperature: 85°C

3. Grind size: medium-coarse (70% passing through a standard No. 20 sieve)

4. Roast level: medium-dark roast

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

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

[Siphon]

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

1. Choice of equipment: Hario siphon

2. Water temperature: 90°C

3. Grind size: medium-coarse (70% passing through a standard No. 20 sieve)

4. Roast level: medium-dark roast

5. Blooming time: 30 seconds

Specific method: side-burn extraction. It is recommended to use 20 grams of coffee for 2 servings, water-to-coffee ratio 1:12, water level mark 2, add the coffee later, add the grounds after bubbling begins, stir 4-5 times, extract for about 30 seconds and turn off the heat, finally stir 2 times, and wait for the coffee liquid to fall freely.

[French press]

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

1. Choice of equipment: French press

2. Water temperature: 92°C

3. Grind size: medium-coarse (70% passing through a standard No. 20 sieve)

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 carafe, start timing, put the lid on the French press with the filter left at the highest position, and 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. Once over-extracted, only sour and bitter flavors can be tasted.

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