Introduction to Indonesian Mandheling Coffee Origin Wet-Hulling Method - Characteristics and Differences Between Aged Mandheling and Golden Mandheling

Introduction

In previous articles, FrontStreet Coffee has explained the importance of fresh coffee beans and the differences between new crop and old crop beans. However, there's one exception: Aged Mandheling. What makes it so special that it attracts coffee enthusiasts with its reputation as an "expired" coffee?

What is Aged Mandheling?

You could say it's the result of an "accident." This story dates back to the Dutch colonial period in Indonesia. Sumatra was one of the world's major coffee bean-producing regions at the time, and the coffee produced had to supply the huge demand of European consumer countries. Indonesia continuously shipped coffee beans to Europe. To ensure a steady supply, coffee beans were appropriately stored. However, due to external factors such as long transportation distances and exposure to sea breezes, the journey took too long. By the time the coffee beans reached Europe, they had developed a unique special flavor that European coffee connoisseurs eagerly pursued.

Therefore, people discovered that aging processed coffee beans for several years causes the acidity to gradually disappear, leaving a solid aftertaste and sweet return characteristics, with a flavor as captivating as Pu-erh tea. However, we can't use "accidental" methods to produce aged beans, as this would undoubtedly add uncertain risks to the coffee bean quality. We must clarify one point: "aged beans" are not simply coffee beans left in a warehouse for several years, because beans left for too long can spoil, or even become moldy or insect-infested. These would not be "aged beans" but spoiled beans. So, gradually, the production model for Aged Mandheling began to standardize and mature.

Aging Process for Mandheling

First, freshly picked coffee cherries must undergo regular processing. For example, FrontStreet Coffee's Aged Mandheling coffee beans are processed using the wet-hulled method. In this process, good beans (plump, large screen size, defect-free) must be carefully selected for aging. After selecting the coffee beans, they are stored in warehouses for aging.

The aging process must be conducted in the origin country, placed in warehouses with temperature and humidity control or good ventilation. During the aging period, the beans must be regularly turned and checked for two purposes: first, to ensure even exposure to air and consistent moisture content; second, to check for any moldy or insect-infested beans to prevent widespread infection.

Today's Aged Mandheling typically ages for 2-3 years. During this period, the acidity of the coffee beans gradually weakens and converts to sugars, and the color becomes deeper, mostly yellowish-brown or dark brown, making it highly recognizable.

What is Golden Mandheling?

The fame of Mandheling coffee originated from Pawani Coffee Company (PWN) successfully launching Mandheling in the Japanese market. Unlike many local green bean suppliers in Indonesia, PWN Company is the exclusive supplier of high-grade Golden Mandheling coffee, contracting the best Mandheling coffee-producing regions in Indonesia, where the produced Mandheling beans are all superior products.

The wet-hulled method saves much time and labor costs in green bean processing. However, the rapid process also brings a higher defect rate, so only strict manual selection can eliminate defects that machines cannot screen out. PWN Company subjects purchased Mandheling green beans to one machine selection plus three manual selections, with quality far exceeding Indonesia's local highest G1 grade, meeting PWN Golden Mandheling production standards, which require the following:

1. Green bean screen size: 18-19 screen or above after first manual selection

2. Fewer than 3 defective beans in a 300-gram green bean sample

3. Green coffee bean grade: G1 grade

4. Dark green color, uniform size, and regular shape

Before launching a coffee bean, FrontStreet Coffee always evaluates it through cupping. Cupping is an evaluation of coffee bean quality and flavor, where unified standards can more objectively identify the strengths and weaknesses of the flavors presented by the beans, as well as their characteristics. Through cupping, FrontStreet Coffee found that the Lindong Mandheling daily bean presents rich nutty notes, with a hint of melon aroma in the finish, and as the temperature drops, herbal plant flavors emerge, with a mellow mouthfeel and saturated aroma. PWN Golden Mandheling not only has aromas of dark chocolate, nuts, and caramel but also herbal spice and pine flavors, with dark chocolate aftertaste, plentiful lingering notes, high cleanliness, and light fruit acidity as the temperature decreases.

Pour-over Parameters for Mandheling Coffee

Brewing water temperature: 87-88°C

Coffee grounds: 15 grams

Coffee-to-water ratio: 1:15

Dripper: KONO dripper

Grind size: Medium-coarse grind (70% pass-through rate with China standard #20 sieve)

Brewing method: Three-stage pouring

Dark roasting makes the internal texture of coffee beans loose, so they can be easily crushed with a gentle pinch by hand. This indicates that the structure of the coffee beans has been significantly altered, and they absorb water strongly after being ground into powder. To avoid over-extraction after the coffee grounds absorb water and release large amounts of bitter substances, FrontStreet Coffee uses a coarser grind than for light roast coffee beans. Here, a medium-coarse grind is used (70% pass-through rate with China standard #20 sieve), with EK43s setting 11 in-store.

Roasting promotes caramelization and Maillard reactions in coffee beans. As the roast level deepens, non-enzymatic browning caused by the interaction and decomposition of monosaccharides and amino acids under heating increases, making it easier to release bitter, large-molecule substances. To avoid extracting too many off-flavors, FrontStreet Coffee reduces the water temperature slightly. The brewing water temperature for light roast coffee is 91-93°C, while FrontStreet Coffee recommends 87-88°C for dark roast coffee beans.

For coffees with mellow mouthfeel like Indonesian Mandheling coffee, Brazilian Queen's Estate coffee, and Jamaican Blue Mountain coffee, FrontStreet Coffee baristas prioritize using the KONO dripper for brewing.

FrontStreet Coffee baristas consistently use the three-stage pouring method. Dividing the pour into three stages better expresses the mellow mouthfeel and caramel sweetness of Golden Mandheling coffee, while providing greater control over time and water volume.

Wetting the KONO dripper allows the filter paper to fit more closely with the coffee dripper. After pouring out the water from the sharing pot, add 15g of ground coffee and bloom with 30g of water for 30 seconds. This initial pour completely wets the coffee grounds for degassing, allowing for better extraction of coffee flavor substances in subsequent steps.

Some friends extend the bloom time to 45 or 50 seconds when extracting light roast coffee beans to enhance the front-end aroma. However, if the bloom time is too long for dark roast Mandheling coffee, it can easily release excessive woody and off-flavors. Therefore, FrontStreet Coffee chooses a 30-second bloom.

For the second stage, start pouring hot water slowly in small circles from the center until reaching 125g, then segment. The water flow needs to be poured steadily throughout. Too vigorous stirring can easily disperse the coffee ground wall, leading to uneven extraction.

Wait until the coffee ground layer drops to half the height of the dripper, revealing the coffee bed, then begin pouring the second stage using the same technique until reaching 225g. Once all dripping is complete, remove the dripper. The extraction time is two minutes, with a 10-second margin of error.

Finally, shake the coffee liquid in the lower pot to mix evenly, and you can start tasting the hand-poured Golden Mandheling black coffee. The brewed Mandheling coffee enters with aromas of spices, dark chocolate, nuts, caramel, and pine, with a mellow yet clean mouthfeel, noticeable aftertaste, and persistent lingering notes.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473