How to Roast and Brew Golden Mandheling Coffee Beans? What's the Pour-Over Ratio for Golden Mandheling?

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Introduction to Mandheling Coffee

Mandheling is a coffee variety produced in Sumatra, Indonesia, Asia, and is therefore also known as Sumatran coffee. The main producing areas include Java Island, Sulawesi Island, and Sumatra Island, with the Mandheling from Sumatra Island being the most famous.

The finest traditional Arabica coffees produced in northern Sumatra are marketed under the names Lintong and Mandheling. To be precise, Lintong refers to coffee grown in a small area in the southwest of Lake Toba in the Lintong administrative region. The coffee growing areas are scattered across a high, undulating plateau covered in ferns and clay soil. Lintong coffee is grown without shade cover, without chemical products, and is almost entirely owned by small private growers.

FrontStreet Coffee - Indonesian Sumatra Lintong Mandheling

Region: Indonesia, Sumatra, Lintong region
Altitude: 1100-1600m
Processing: Wet-hulled method
Variety: Timtim, Ateng
Flavor Notes: Toasted bread, nuts, caramel, herbs, chocolate

FrontStreet Coffee believes that Mandheling coffee has rich aromas, a solid and mellow mouthfeel, low acidity, and is quite intriguing. When dark roasted, you can experience its lingering bitterness while enjoying its elegant sweetness, feeling its unique stuffy aroma through both smell and taste.

Based on their understanding of Mandheling coffee, FrontStreet Coffee's roasters decided to maximize the expression of Mandheling's flavors while preserving its own style and making it suitable for most people's tastes. Each specialty coffee shop has its own characteristics, and FrontStreet Coffee hopes to showcase the best Mandheling while retaining FrontStreet Coffee's unique characteristics. FrontStreet Coffee currently sells two types of Mandheling coffee beans: one is the Lintong region Mandheling coffee beans mentioned above, and the other is the Gold Mandheling coffee beans from PWN company in Aceh Gayo Mountain.

FrontStreet Coffee - Indonesian Sumatra PWN Gold Mandheling Coffee Beans

Region: Indonesia, Sumatra, Aceh Gayo Mountain
Altitude: 1100-1600m
Processing: Wet-hulled method
Variety: Ateng
Flavor Notes: Spices, nuts, pine, caramel, herbs, chocolate

The difference between the two is that PWN Gold Mandheling coffee beans undergo at least three rounds of pure manual selection after harvesting and drying processing, ensuring that the coffee bean specifications reach above 18. Defective beans are fewer than 3 (in a 300g green bean sample), belonging to the highest G1 grade. PWN beans are darker green in color and have a uniform flat shape.

What are the Differences Between Mandheling Coffee Beans at Different Roast Levels?

For this purpose, FrontStreet Coffee tested light roast, medium-dark roast, and dark roast Mandheling coffee beans using pour-over extraction (hand drip) - single serving, with slight adjustments in grind size and water temperature for different roasts.

1. Light roast: 80% pass-through rate on national #20 screen, water temperature 90°C, water-to-coffee ratio 1:15
2. Medium-dark roast: 75% pass-through rate on national #20 screen, water temperature 88°C, water-to-coffee ratio 1:15
3. Dark roast: 70% pass-through rate on national #20 screen, water temperature 86°C, water-to-coffee ratio 1:15

Test Results:

1. Light roast: At this roast level, Mandheling has heavier fruit acidity, slightly bitter, with noticeable fruit acidity that is comfortable on entry, creating a mouth-watering sensation on both sides of the mouth, with average smoothness.
2. Medium-dark roast: Very well-balanced, rich and mellow, with more obvious bitterness, chocolate and slight sweetness more prominent, obvious licorice aroma, weak fruit acidity, better smoothness than light roast, strong aroma, with noticeably enhanced fruit acidity.
3. Dark roast: Almost no acidity, very heavy bitterness. If direct fire roasting is slightly improper, it may produce burnt flavors.

All coffee beans sold by FrontStreet 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 completion.

The deeper the roast level, the more carbon dioxide is produced inside the coffee beans. After roasting completion, the coffee beans contain abundant carbon dioxide, so don't rush to drink them. You can first let the beans rest for 3-5 days (counting from the roasting date), allowing the coffee beans to naturally release some carbon dioxide in their original packaging, reducing the situation of uneven extraction caused by excessive carbon dioxide bubbles during the extraction process.

Mandheling Coffee Bean Processing Method - Sumatra Wet-Hulled Method

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

1. Coffee fruit depulping: Place the parchment beans in a large container or tank filled with water, and scoop out the defective parchment beans floating on the liquid surface.

2. The dense parchment beans that sink to the bottom are briefly cleaned, removed and placed in buckets or plastic bags for a brief dry fermentation process, which allows the pectin sugars on the seed coat surface to ferment and enhance flavor. Basically, the longer the fermentation time, the stronger the acidity. Fermentation time varies by person, generally only a few hours, but some estates skip the dry fermentation stage and directly sun-dry the parchment beans to reduce acidity and increase viscous mouthfeel, allowing full fermentation of pectin sugars to enhance flavor. Usually, fermentation time is between 12-36 hours, depending on specific conditions.
3. Sun-dry the parchment beans for one to two days until the bean moisture content reaches 30%-50%, while the beans are still semi-hard and semi-soft. Use a hulling machine to remove the seed coat and continue drying, accelerating the drying process. After about two days, when the moisture content reaches 12%-13%, the coffee beans are collected into woven bags, typically 40kg and 80kg per bag, and sent to coffee processing factories for dehulling. The process is completed in about four days.

The dehulling process involves grinding off the bean hulls with a hulling machine, then continuing to dry until the moisture content reaches approximately 12%-15%. Then, the coffee beans are sent for mechanical sorting to remove various impurities and classified by particle size. Of course, accidents can happen. During the hulling process, the coffee bean temperature can rise to 30-60°C and completely destroy the parchment layer, potentially triggering bean germination. The wet-hulled method can also result in a higher proportion of defective beans such as moldy beans compared to washed and natural methods because the fruit skin is removed during processing, exposing the beans directly to air. Mold brings good flavor because coffee beans have four protective layers: fruit skin, pulp, parchment, and silver skin.

In the washed method, only the first two layers are removed, preserving the parchment and silver skin for sun drying. However, the wet-hulled method removes the third and fourth protective layers midway, exposing them to direct sunlight, which is why Sumatra green beans have a blue-green color. Although the wet-hulled method shortens drying time, the chances of exposure to mold, fungi, and yeast also increase significantly. Interestingly, contamination is not necessarily a bad thing, depending on the strain. Dr. Martha Taniwaki from the Brazilian Food Technology Research Institute once experimented with different fungal strains infecting coffee beans, producing different flavors including rotten, oily, moldy, woody, iodine, caramel, chocolate, and floral aromas.

Academic circles believe that the woody, herbal, earthy, banana, and spicy flavors of Sumatra coffee should be created by mold. Roasting plant managers often report to academia that some infected moldy coffee beans have better flavor after thorough cleaning, while others are difficult to swallow, which is related to the strain. Perhaps it's possible to inhibit bad mold and implant good mold, control wild yeast, and cultivate elegant yeast. But which molds help enhance coffee flavor? Which are bad bacteria? Further research is still needed.

Elephant Beans: The "ID 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 four protective layers are in an exposed state, making them more likely to trigger germination compared to washed beans that have only lost two protective layers. This activates the metabolism of sugars, proteins, and fats, which are all precursor aromatic compounds of coffee. Additionally, the friction generated during the hulling process raises the bean temperature to 30°C-60°C, which also facilitates germination and mold growth.

Moreover, the semi-hard, semi-soft moist green beans are easily bruised by mechanical force during hulling, causing the beans to crack open in a cloven-hoof shape. This is why Sumatra has a higher proportion of elephant beans. But whether elephant beans are good or bad remains inconclusive to this day. The key to control is maintaining clean equipment and beans. Once hulled, drying must be quick to produce a mellow, low-acid, and sweet Sumatra flavor; if control is improper, it may result in bland Sumatra coffee, or even moldy earthy flavors. If you prefer stronger acidity, Aceh can also be washed, depending on customer needs.

Summary of Wet-Hulled Processing Flavor Characteristics

To summarize the wet-hulled flavor, removing the subtle differences, we generally believe that wet-hulled beans have earthy, smoky, and chocolate flavors. They are mellow yet seem quite dull, with low acidity stemming from the shorter, less effective fermentation process and longer drying time. If you forgot about wet-hulled fermentation, go back and review.

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

There are many sources of defective beans in the wet-hulled method. First, natural defects from the coffee fruit itself are inevitable, another contributor to defects is the dehulling part, plus corrosion during transportation of wet parchment beans, damage to exposed green beans from sunlight and moisture, and irregular weather causing uneven drying speeds that also detract from flavor. This is why Mandheling requires so many rounds of manual selection.

Finally, FrontStreet 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 brewing methods will produce different tastes. Next, FrontStreet Coffee will use the store's PWN Gold Mandheling coffee beans as an example to analyze the flavor characteristics using four different brewing methods.

【Pour-over】

Flavor: Multi-layered, clean, balanced, with persistent caramel sweetness in the aftertaste

1. Equipment choice: Hario V60
2. Water temperature: 88°C
3. Grind size: Medium-coarse (70% pass-through rate on standard #20 screen)
4. Roast level: Medium-dark
5. Bloom time: 25 seconds

Specific technique: Three-pulse pour-over for Mandheling: 15g coffee, ground with Fujiyama mountain serrated burrs #4, V60 dripper, water temperature 88-89°C. First pour 30g water for 25s bloom, then pour to 104g and pause, wait until the water level in the bed drops to half before continuing the pour, slowly pour until reaching 220g total water, avoid the last 5g. Water-to-coffee ratio 1:15, extraction time around 2:00.

Volcanic pour-over extraction for Mandheling, or using flannel or Kono is also possible!

Specific technique: High-temperature extraction, water temperature 90-92°C, small water flow in the early stage at coin-sized spot, pause, bloom, pause, bloom, keeping the grounds in a continuous blooming state for 1:30 bloom time, finally use large water flow for quick extraction, total extraction time 2:30.

【AeroPress】

FrontStreet Coffee believes that Mandheling coffee brewed with AeroPress has rich and complex flavors, with prominent spice notes and fresh forest aromas.

1. Equipment choice: AeroPress
2. Water temperature: 85°C
3. Grind size: Medium-coarse (70% pass-through rate on standard #20 screen)
4. Roast level: Medium-dark
5. Bloom time: 2 times, first 20 seconds, second 50 seconds

Specific technique: AeroPress standard preparation, recommend adding 20g coffee grounds, water-to-coffee ratio 1:17. First pour 83°C hot water to 100g, stir 3-5 times to fully wet the coffee grounds, let stand for 20s, add remaining hot water to reach 240g, let stand for 40s, stir 5s, when it reaches 1 minute 50 seconds, insert the plunger and press down. Total time 2 minutes 5 seconds.

【Siphon】

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

1. Equipment choice: Hario siphon pot
2. Water temperature: 90°C
3. Grind size: Medium-coarse (70% pass-through rate on standard #20 screen)
4. Roast level: Medium-dark
5. Bloom time: 30 seconds

Specific technique: Side-burn extraction, recommend 20g coffee for 2 servings, water-to-coffee ratio 1:12, water level to mark 2, using post-addition method (add grounds after water boils), wait for bubbles to subside before adding grounds, stir 4-5 times, extract for about 30 seconds then remove heat, finally stir 2 times and let the coffee liquid drain freely.

【French Press】

Flavor: Balanced, mellow, good body and oils, with slight sweetness

1. Equipment choice: French press
2. Water temperature: 92°C
3. Grind size: Medium-coarse (70% pass-through rate on standard #20 screen)
4. Roast level: Medium-dark
5. Bloom time: 2 minutes 30 seconds

Specific technique: 20g coffee beans, pour hot water (about 92-93°C) into French press to the 300ml mark on the pot, start timing. Place the lid on the French press with the filter stopped at the highest position, wait for 2.5 minutes. Press the filter to the bottom.

Conclusion

Recommend using pour-over and AeroPress methods to showcase the rich and mellow flavors of PWN Gold Mandheling. Siphon and French press methods are more likely to cause over-extraction, and once over-extracted, you can only taste sour and bitter flavors.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473