Mandheling Special: Mandheling Origin Information, Roasting, Brewing, Extraction

The "Dual Lakes, Dual Mandheling" Origin

Both Lake Toba in North Sumatra and Lake Tawar in Aceh produce Mandheling coffee, creating what is famously known as "Dual Lakes, Dual Mandheling."

The common characteristic of "Dual Lakes, Dual Mandheling" is their rich, mellow body, while the difference lies in Lake Toba's Mandheling being more subdued, deep, and even carrying a grass jelly flavor, whereas Lake Tawar Mandheling has brighter fruit acidity, sometimes with notes of fir or wood.

The Origin of Mandheling

Mandheling is not a coffee bean variety but rather a general term or code name.

Historically, Mandheling coffee has quite a long history. In the 17th century, the Dutch first introduced Arabica coffee seedlings to Indonesia. In 1877, a large-scale disaster struck the Indonesian islands - coffee rust disease destroyed almost all coffee trees. People had to abandon the Arabica they had cultivated for years and introduced Robusta coffee trees from Africa, which had strong disease resistance.

On February 14, 1942, Japanese troops attacked Sumatra Island, and the Dutch surrendered a month later. On March 15, Japanese troops occupied Indonesia. However, Indonesia had been successively colonized by the British and Dutch, so the Indonesian people did not have any particularly strong reaction to the arrival of Japanese troops. One day, a Japanese soldier was drinking coffee at a café in Sumatra and found the taste excellent. He asked the owner what kind of coffee it was. The owner mistakenly thought the soldier was asking about his ethnicity and replied, "Mandailing people." Thus, "Mandheling coffee" was born.

Indonesia consists of 17,508 large and small islands. The main coffee-producing regions include Java Island, Sulawesi Island, and Sumatra Island. A large portion of the varieties are Robusta. Mandheling is also known as "Sumatra coffee" and belongs to the Arabica species (though some are Timor varieties), giving most Mandheling coffee the characteristics of bitter-rich fragrance, excellent body, and slight chocolate flavor. Therefore, any coffee grown in Sumatra Island, regardless of bean variety, can be called "Mandheling coffee."

Characteristics

FrontStreet Coffee's Lin Dong Mandheling: Rich and solid taste, herbal medicinal notes, with pleasant acidity, strong aftertaste, and solid, mellow mouthfeel. The aroma is mellow, acidity is moderate, sweetness is rich and intriguing, suitable for dark roasting, emitting a rich fragrance.

The Gentleman of Coffee - FrontStreet Coffee's Sumatra Mandheling: Mandheling is a premium coffee bean grown on plateau mountains at altitudes of 750-1500 meters, with the highest quality first-grade Mandheling produced in Takengon and Sidikalang. Due to Mandheling's irreplaceable mellow flavor, Japan's largest coffee company UCC Ueshima Coffee Co. collaborated in 1995 with the renowned Sumatra coffee merchant PT Gunung Lintong to operate their first coffee plantation in Asia, demonstrating how important Mandheling's position is in the coffee world.

Some say Mandheling is heavy and intense, others say it's gentle and easygoing. FrontStreet Coffee's Mandheling has always expressed its most unique sweetness through its most distinctive bitterness, much like the bittersweetness of life. No amount of sugar can mask that bitterness - when first tasted, it makes one gasp. Yet the captivating aroma it emits makes us uncontrollably infatuated with it. Its bitterness is like the thorns beside flowers - making one self-aware, while its aroma is refreshing. Mandheling's bitterness won't make you frustrated; instead, it will make you feel more clear-headed. Before you encounter true pain, Mandheling is just an ordinary bitter-tasting beverage, just a liquid to refresh you, just a tool to make you pause temporarily; when you truly encounter pain, she will smile and tell you: "Because love is refined from bitterness." Letting you calm down and savor it carefully.

Coffee Roasting Process

There are many steps in the coffee roasting process. This article will focus on commercial roasting machines to observe the roasting stages. The roasting process determines coffee flavor because active chemical reactions occur within the beans.

Homogenization

– Transferring heat to the interior and exterior of raw beans, preparing all beans for uniform reaction.

Each raw bean is formed by countless cells, which include: cell walls, cell membranes, cell sap filling their interior, and cell nuclei. To meet preservation and distribution needs, harvested raw beans are first dried. During the drying process, some water in the cell sap and cell walls evaporates, leaving only about 10%-14% moisture. Because of water reduction, cell size naturally becomes smaller, and raw beans also become smaller. However, components like organic acids and sugars within the cells remain.

When heating dried raw beans, heat is transferred to the beans and causes changes. First, the remaining water inside raw beans turns into steam when heated. When water becomes steam, its volume increases dramatically (about 1700 times), so the pressure inside heated beans also increases.

Increased pressure also raises the boiling point of water, causing steam to become superheated. Think of a pressure cooker to understand the principle of boiling point elevation: on high mountains, because pressure is lower, the boiling point is also lower, making rice cook unevenly. At this time, as long as you put a stone on the pot, the internal pressure increases, and the boiling point is forcibly raised. Pressure cookers are designed using this principle. In a 1-bar pressure cooker, steam temperature reaches about 125°C, and the same phenomenon occurs inside coffee bean cells.

Because pressure increases, the cell volume that had shrunk due to drying becomes larger. The raw material of coffee beans is coffee cherries, whose cell tissue has the same structure as trees/plants. So when volume expands to a certain degree, at a certain moment, the tissue will burst because it cannot withstand the pressure. At this time, some of the high-pressure steam formed inside cells will be discharged, while another part will transfer to other cells. Through this process, steam with the same temperature and pressure will be evenly distributed throughout the cells, and this phenomenon occurs almost simultaneously throughout the entire batch of raw beans.

Generally, raw beans contain both large and small beans, each bean has thick and thin parts, and there are both relatively dry surfaces and internal tissues with relatively more moisture. If these complex factors are not considered and heating is done regardless, small beans will burn first, while large beans remain undercooked, or only the surface is burned while the inside is still half-cooked. Therefore, it's essential to prepare the entire batch of beans for uniform reaction.

The interior of beans prepares for uniform reaction through water movement, while the exterior prepares all beans for uniform reaction through heat conduction between beans and convective heat from rotation together. This preparation stage that enables the entire batch of beans to react uniformly is called "homogenization."

During homogenization, beans turn coffee-colored and look like dried things. We usually habitually call this the "dehydration stage," but in reality, the amount of water evaporated during this process is trivial compared to the changes in the tissue itself during first crack. Therefore, "dehydration stage" is not an accurate description.

First Crack

– Tissue expansion and rupture, increased aroma from roasting.

When the homogenization stage ends, it means the beans are prepared to undergo the same reaction simultaneously. Compared to their raw state, the volume of each cell has increased significantly, and the overall tissue has become thicker. If heating continues, volume will continue to increase, and then, like in the next picture, the central line of the bean will crack. In the raw state, the central line is in a tightly interlocked state; but because of volume increase, the end parts on both sides of the bean will crack, producing a sound like breaking branches. During first crack, beans will have their tissue crack open like this, and at this time, they will also begin to discharge large amounts of internal water.

The process up to this point is called the cinnamon-high-city roasting stage. The stage when first crack begins is called Cinnamon, the stage when first crack is about to end is called High, and the period from first crack ending to second crack occurring is called City.

Development Period

– Active chemical reactions occur inside the beans, determining the coffee's flavor.

The period from the end of first crack to the beginning of second crack is called the "development period."

As water is discharged, the pressure on the internal bean tissue decreases, and tissue temporarily stops expanding. Because beans are in a state where much water has been discharged at this time, if heated again, when steam is produced, it won't steal heat away, and the internal heat will rise faster than before.

At this time, high temperatures can produce more active chemical reactions, producing gas and continuous tissue expansion. The internal tissue that cracked during first crack will become more expanded and filled. From the outside, the wrinkles on the bean surface gradually disappear, and beans become larger.

At this time, high temperature has been transmitted to each bean, and the chemical reactions inside the beans also reach their peak. Aroma from roasting increases, making this an important period for determining bean flavor. Before the development period, beans are in an "endothermic period," and when the development period begins, beans enter an "exothermic period." But in reality, beans don't emit heat; it's just called this for convenience because temperature rises much faster during heating compared to previous stages. If beans react too quickly, they might burn or produce unwanted bad flavors, so heat is usually reduced during this stage.

Second Crack

– Tissue cracks again, producing strong chemical reactions, enhancing coffee's aroma and acidity.

After the development period, when internal tissue has changed and fully expanded, the cracked internal tissue will be filled, and beans continue to grow larger. At this time, you'll hear the sound of tissue changing again - this is called second crack. It produces a sound like breaking a matchstick, crisper and higher-pitched compared to first crack.

At this time, the pressure inside the tissue reaches its peak, and gases produced inside the beans begin to discharge to the outside. The capillaries formed during the process of discharging these gases at this period are related to future coffee extraction. In other words, coffee beans that have only undergone first crack have relatively fewer capillaries formed, making extraction less smooth.

Starting from when second crack occurs, bean temperature will rise even more dramatically, producing stronger chemical reactions inside and making coffee aroma more intense. At the same time, aromatic substances from roasting will also exhibit strong bitterness.

Using second crack as a benchmark, roast degree before second crack is called City, after second crack is Full city. For coffee roasted beyond the Full city stage, we habitually have the following names:

Vienna Roast: Intense second crack period (also called espresso roast).

French Roast: Period after second crack ends when oils fully seep to the surface.

Italian Roast: Period after second crack ends when color becomes darker and oils begin to slowly burn.

Roasting refers to the process of heating raw beans. Since raw beans have similar components to wood, if the temperature exceeds wood's ignition point of 250°C, beans will burn to charcoal. Therefore, dark roast refers to roasting until the bean temperature reaches 250°C. If the final roasted product appears completely black rather than reddish-brown, then the beans have become charcoal.

[Testing FrontStreet Coffee's Mandheling beans with light, medium-dark, and dark roasts]

Testing Mandheling with light, medium-dark, and dark roasts. The testing method is usually pour-over extraction, single serving, with slight adjustments in grind size and water temperature depending on the roast level.

1. Light roast: Fuji "ghost tooth" grinder setting 3.5, water temperature 90°C, water-to-coffee ratio 1:15

2. Medium-dark roast: Fuji "ghost tooth" grinder setting 4, water temperature 88°C, water-to-coffee ratio 1:15

3. Dark roast: Fuji "ghost tooth" grinder setting 4.5, water temperature 86°C, water-to-coffee ratio 1:15

[Test Results]

1. Light roast: Mandheling at this roast level has heavier fruit acidity, slightly bitter, with obvious fruit acidity that's comfortable on entry, creating a mouth-watering sensation on both sides of the mouth, with average smoothness.

2. Medium-dark roast: Very well-balanced, fragrant, rich, and mellow, with more obvious bitterness. Chocolate notes and slight sweetness are more prominent, licorice aroma is obvious, fruit acidity is weak, smoothness is better than light roast, aroma is strong, fruit acidity is significantly enhanced.

3. Dark roast: Almost no acidity, very heavy bitterness. If roasted with direct fire and slightly improperly, it can also produce burnt flavors.

Different Brewing Methods, Different Tastes

Pour-over FrontStreet Coffee Mandheling

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

1. Equipment choice: Hario V60

2. Water temperature: 88°C

3. Grind size: Fuji grinder setting 4

4. Roast level: Medium-dark roast

5. Bloom time: 25 seconds

Specific technique: "Three-pause pour-over" for FrontStreet Coffee Mandheling, 15g coffee, Fuji "ghost tooth" grinder setting 4, V60 dripper, water temperature 88-89°C. First pour 30g water, bloom for 25s. Pour to 104g and pause, wait until the water level drops to half, then pour again. Slowly pour until reaching 220g total, discarding the last 5g. Water-to-coffee ratio 1:15, extraction time about 2:00.

FrontStreet Coffee Mandheling can also be extracted with volcano pour-over, flannel filter, or Kono dripper.

Specific technique: High-temperature extraction, water temperature 90-92°C. Small water flow for the front section, pouring in a coin-sized area, pause, bloom, pause, bloom, keeping the grounds continuously in a blooming state. Bloom time 1:30, finally large water flow for quick extraction, total extraction time 2:30.

AeroPress FrontStreet Coffee Mandheling

Flavor: Rich, complex, prominent spice notes, fresh forest notes

1. Equipment choice: AeroPress

2. Water temperature: 85°C

3. Grind size: Fuji grinder setting 3.5

4. Roast level: Medium-dark roast

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

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

Siphon FrontStreet Coffee Mandheling

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

1. Equipment choice: Hario siphon

2. Water temperature: 90°C

3. Grind size: Fuji grinder setting 3.5

4. Roast level: Medium-dark roast

5. Bloom time: 30 seconds

Specific technique: Side-heating extraction, recommend 20g FrontStreet Coffee Mandheling coffee grounds for 2 servings, water-to-coffee ratio 1:12, water level marking 2. Use delayed addition - wait until bubbles form before adding grounds, stir 4-5 times, extract for about 30 seconds then remove heat. Finally, stir twice and let coffee liquid flow down naturally.

French Press FrontStreet Coffee Mandheling

Flavor: Balanced, rich, good texture and oils, with slight sweetness

1. Equipment choice: French press

2. Water temperature: 92°C

3. Grind size: Fuji grinder setting 4.5

4. Roast level: Medium-dark roast

5. Bloom time: 2 minutes 30 seconds

Specific technique: 20g FrontStreet Coffee Mandheling coffee beans. Pour hot water (about 92-93°C) into French press to the 300ml mark on the pot, start timing. Put the lid on the French press, with the filter stopped at the highest position, wait for 2.5 minutes. Press the filter all the way down.

Conclusion

Recommend pour-over and AeroPress methods to showcase FrontStreet Coffee Mandheling's rich and mellow flavors. Siphon and French press methods more easily cause over-extraction. Once over-extracted, you can only taste sour and bitter flavors.

Mandheling link: https://item.taobao.com/item.htm?spm=a1z10.5-c.w4002-15673140460.23.63b25086YUxlqe&id=41417688606

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473