Why does golden mandheling coffee taste sour when hand-brewed?

Golden Mandheling coffee should drink bittersweet and full-bodied, with herbal aroma, rear-palate sweetness and a smoky finish. A faint tartness usually comes from the brew rather than the bean: too fine a grind, water that is too hot, or a rushed pour can pull acidity forward, while the wet-hulling process and the Ateng variety behind the name already keep natural acidity low.

The name traces back to the Mandailing people of Indonesia and a wartime mishearing that became Mandheling. For a balanced cup, use staged extraction on a Kono dripper: a slower first pour to saturate the grounds, then a steady main pour, keeping the roast curve in mind so the mandheling sweetness arrives before any sour edge.

Many friends who are just getting into single-origin coffee often order a Mandheling just to avoid acidity. But sometimes the Mandheling comes out with a slight tartness, which seems different from the bitter-sweet, full-bodied flavor they expect. What exactly should Mandheling taste like? This article traces the bean's origins from the name Mandheling, the definition of PWN Golden Mandheling, the characteristics of the Ateng variety, to the wet-hulling process, and analyzes the root causes of the acidity. It also includes Front Street Golden Mandheling's roasting curve and Kono dripper staged extraction parameters, to help enthusiasts understand the flavor layers of Mandheling and brew a full-bodied, balanced cup.

There are always some friends who aren't too keen on acidity and are just starting to explore single-origin coffee. They walk into a café and say to the barista, "Give me a pour-over that's not sour." At that point, the barista will almost certainly bring out Mandheling coffee beans. When it's brewed and served, the first sip usually gets feedback of bitterness—some even can't resist adding sugar. Front Street still remembers their first time drinking Mandheling. What surprised me wasn't the bitterness, but the herbal aroma that wafted up before the sip, the sweetness that burst on the rear palate after swallowing, and the smoky aftertaste that lingered in the mouth. But later, at a different café, I ordered Mandheling again, and the first sip felt off—I could actually taste a faint acidity. Shouldn't Mandheling be bittersweet, sweet within bitter? Why would there be acidity? What exactly should Mandheling taste like?

The Origin of the Name Mandheling

The earliest name for Mandheling was actually Mandailing, which originally referred to the name of a tribe in Indonesia. During World War II, when Japan occupied Indonesia, a Japanese soldier drank a cup of extremely rich and aromatic coffee at a local café and asked the owner what the coffee was called. The owner mistakenly thought he was asking where he was from, so he answered: "Mandailing."

After the war ended, the Japanese soldier recalled the rich coffee he had drunk in Indonesia and, through a friend's connection, found a local coffee merchant in Indonesia to help ship 15 tons to Japan. When others asked the name of the beans, he mistakenly said "Mandehling" instead of "Mandailing." It was this "double misunderstanding" that spread the word Mandheling. Because Mandheling coffee became very popular in Japan, the name spread along with it—and that coffee merchant was none other than the now-famous Pwani Coffee Company (PWN).

PWN Golden Mandheling

When it comes to Mandheling flavor, the first thing people often think of is "Golden Mandheling," an Indonesian Mandheling coffee bean. However, have you noticed that certain English letters are always tied to the name Mandheling, such as Front Street PWN Golden Mandheling?

Actually, PWN (Pwani Coffee Company) is the abbreviation for Pwani Coffee Company. This company is quite famous locally in Indonesia, mainly engaged in purchasing Indonesian Mandheling coffee beans. It has acquired almost all of Indonesia's best-producing regions, so most Indonesian Mandheling beans from PWN have uniquely high quality. After collecting the beans, PWN also performs multiple rounds of manual hand-sorting to select plump, defect-free beans. Only such beans are classified as Golden Mandheling.

Later, PWN registered "Golden Mandheling" as a trademark. Front Street PWN Golden Mandheling thus became the case that today only Golden Mandheling produced by this company counts as true "Golden Mandheling." Front Street needs to clarify that most Front Street PWN Golden Mandheling on the market currently comes from the Aceh region of Sumatra.

Ateng

FrontStreet Coffee's 2020 new-crop Front Street Mandheling coffee beans are of the Ateng variety, which is Catimor. Only Catimor grown in Sumatra and Indonesia's native islands can be called Ateng. Catimor is not what is usually called pure Arabica, but a hybrid of Timor from the Robusta species and Caturra, a Bourbon variety.

It was first successfully developed in 1959 and began to be promoted in Brazil in the 1970s and 1980s. With its disease resistance and high yield, Catimor earned a place among Central and South American coffee varieties. The recurring coffee leaf rust crises in Central and South America also drove

Wet-Hulled Method

When it comes to Indonesian Mandheling coffee, what leaves a lasting impression is probably the rich cocoa flavor on the palate, along with its distinctive herbal and earthy notes. The formation of this unique flavor profile is actually related to the way Mandheling coffee is processed.

Just as K72 is to Kenya and honey processing is to Costa Rica, the wet-hulled method can be said to be a highly distinctive processing method unique to Indonesia. Because local water resources are precious and sun-drying conditions are unstable, locals combined Indonesia's rainy climate and invented the wet-hulled method.

The wet-hulled method process is as follows:

1. After the coffee cherries are depulped, the parchment beans are placed into a large bucket or tank filled with water, and defective floating parchment beans are skimmed off the surface.

2. The dense parchment beans that sink to the bottom are briefly washed, then removed and placed into a bucket or plastic bag for a brief dry-body fermentation—that is, allowing the mucilage sugars on the surface of the parchment to ferment and enhance flavor. Basically, the longer the fermentation, the stronger the acidity. Fermentation time varies from person to person; generally it is only a few short hours, but some estates skip dry-body fermentation and directly sun-dry the parchment beans to suppress acidity and enhance a syrupy mouthfeel, allowing the mucilage sugars to fully ferment and increase flavor. Typically the fermentation time is between 12 and 36 hours, depending on the specific circumstances.

3. The parchment beans are sun-dried for one to two days, until the bean moisture content reaches 30%–50% and the beans are still half-hard and half-soft. Then a huller is used to scrape off the parchment, and they are dried 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 plant for hulling. All done—roughly four days from start to finish.

4. The hulling process uses a huller to grind off the bean parchment, then the beans are dried again until the moisture content reaches about 12%–15%. After that, the coffee beans are sent for machine sorting to remove various impurities, and then classified by bean size.

The wet-hulled method also, because the parchment is scraped off during production, exposes the beans directly to air, resulting in moldy beans and other defective beans at a rate far higher than in washed and natural methods. It is precisely for this reason that Mandheling has those distinctive notes of grass jelly, herbs, and earth.

In people's impression, Mandheling should be bittersweet—so why would it have acidity?

In fact, looking at Mandheling green beans themselves, this is a coffee bean with extremely high acidity. Its acidity transformation characteristic lies in the fact that, under light-medium, medium, and medium-dark roasting, the fruity acidity will undergo a change from quite pronounced strong acidity to acidity to weak acidity.

Front Street Coffee once tried roasting Front Street Golden Mandheling to light, medium, and dark roast levels to compare the differences, and found that actually no matter whether it is light, medium, or dark roast, the flavor is never bad.

The reason the Mandheling we commonly see is dark-roasted is, first, because its processing method and the jumbled varieties make this bean have a relatively high defect rate, and dark roasting can perfectly mask this flaw; second, because Mandheling was mainly first discovered by the Japanese, and the Japanese in coffee tasting also tend to prefer mouthfeel-oriented coffees. So it is not hard to understand why Mandheling chooses dark roasting.

Coffee beans are the fruit of the coffee tree, and every fruit carries the characteristic of natural fruity acidity. The "acidity" in coffee is also affected by roasting and extraction—how the roaster roasts and how the barista brews will all affect the flavor of a cup of coffee. If you really do not want Mandheling with acidity, then you might as well choose beans with a relatively dark roast level; after all, the longer the roasting time, the more the floral and fruity acidity substances in the coffee have been ground away. But Front Street believes that fruity acidity can be said to be an indispensable member of a cup of coffee, because it is precisely these acidic notes that make the flavor layers of coffee full and rounded, and this is also what gives every cup of coffee its own unique personality.

Front Street Coffee: Front Street Golden Mandheling Coffee Beans

Company: PWN

Region: Gayo Mountain, Aceh, Sumatra

Altitude: 1100-1600m

Variety: ateng

Processing Method: Wet-Hulled Method

[Roasting Suggestions]

When Front Street Coffee roasts Front Street Golden Mandheling coffee beans, the roast level is medium-dark, in order to erase Mandheling's excessive acidity and enhance its body and balance. Front Street Golden Mandheling is a green bean with relatively high moisture content, and compared with natural beans it has a relatively high deviation value in moisture, so special attention must be paid during dehydration. Front Street Coffee suggests that after loading the green beans, immediately close the air damper, let it steam for 30 seconds, then open the air damper to 3, until the green bean color turns light green or white, then open the air damper to 4, and after first crack open it to the maximum.

Machine: Yangjia 800N, green bean charge 550g

Charge temperature: 200℃

Turning point: 5'40", 148℃

First crack: 9'54", 191.2℃

Develop for 3 minutes 30 seconds after first crack, discharge at 204.5℃

[Brewing Suggestions]

Front Street suggests using freshly roasted coffee beans for brewing, as this allows you to experience the coffee's rich flavors to the greatest extent. The coffee beans shipped by Front Street Coffee are all within 5 days of the roast date, because Front Street deeply understands that the freshness of coffee beans has a great impact on flavor. Front Street's roasting philosophy is "freshly roasted good coffee," so that every customer who places an order receives the freshest coffee when they get it. The resting period for coffee is about 4-7 days, so when the customer receives it, it is exactly at its best flavor.

Dripper: Kono dripper

Water temperature: 88℃

Dose: 15 grams

Coffee-to-water ratio: 1:15

Grind size: medium-fine grind (EK43s setting 11)

*Reason for choosing the Kono dripper: The Kono dripper has few ribs and they are located at the lower end. The filter paper fits closely against the dripper, which can restrict airflow and extend the contact time between water and coffee grounds, allowing the coffee grounds to be fully extracted and enhancing the syrupy mouthfeel.

Brewing method: staged extraction

Use 30 grams of water for a 30-second bloom, then pour in a small stream in circles until 125 grams for the staged pour. When the water level is about to expose the coffee bed, continue pouring until 225 grams and stop pouring. When the water level is about to expose the coffee bed again, remove the dripper. (Timing starts from the beginning of the bloom.) The extraction time is 2'00".

Front Street Mandheling coffee characteristic mouthfeel description: multi-layered and varied, full-bodied and clean, highly balanced, with strong nutty and chocolate flavors, rich spice and caramel aromas, a fruity note, and a long finish.

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