Why Do Coffee Beans Develop Oily Residue? PWN Golden Mandheling Coffee Beans Develop Oil Due to Medium-Dark Roasting

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Recently, the Gayo Mountain region in Sumatra, Indonesia introduced a triple hand-picked Mandheling coffee bean (also known as Golden Mandheling by coffee merchants). Many friends asked FrontStreet Coffee about the differences between this Golden Mandheling coffee bean and FrontStreet Coffee's PWN Golden Mandheling coffee bean. To address this question, FrontStreet Coffee immediately acquired this Golden Mandheling and conducted a series of comparisons with the existing FrontStreet Coffee PWN Golden Mandheling coffee beans.

What is PWN Golden Mandheling?

PWN is the abbreviation for Pwani Coffee Company, a renowned Indonesian green coffee bean merchant. "Golden Mandheling" was registered as a trademark by PWN Company early on, making these five characters exclusive to PWN. The "Gold Top Mandheling" registered by Japanese companies that we see in the market, and the triple-selected Gayo Mountain Mandheling mentioned below, despite having similar flavors, are not truly Golden Mandheling coffee beans.

FrontStreet Coffee PWN Golden Mandheling's Strict Selection Process

FrontStreet Coffee PWN Golden Mandheling coffee beans originate from Lake Tawa in Mount Gayo, northwestern Sumatra. The specification standard for FrontStreet Coffee Golden Mandheling is 18 screen or above, with fewer than 3 defective beans (in a 300g green bean sample), belonging to the highest grade G1 level. The beans are deep green in color and display uniform flat shapes.

As everyone knows, Indonesian green coffee beans are processed using the wet-hulling method. Because semi-hard and semi-soft moist beans are easily damaged when the parchment and mucilage layers are removed, the beans crack open like goat hooves when injured. These are commonly known as "goat hoof beans." Although these goat hoof beans are not defective, PWN Company believes they don't look as appealing, so they are filtered out to give everyone a sense of uniformity.

One might think that 18 screen or above, with fewer than 3 defective beans in 300g of green coffee beans, and filtering out goat hoof beans is already very strict, but PWN Company can achieve even more extreme rigor. After three rounds of manual selection, the beans are uniformly placed in machines for density and color sorting, finally presenting Mandheling coffee beans with uniform color and consistent bean shape. It is said that when processing the green beans, the Mandheling beans emit a golden luster under sunlight, hence the name Golden Mandheling.

After strict selection, FrontStreet Coffee discovered that not only is the characteristic earthy impurity of regular Mandheling eliminated, but it also provides a clean and transparent taste while maintaining high body.

How to Identify Authentic PWN Golden Mandheling?

Two key points: the certification provided by PWN Company and the clear PWN Company logo on the green bean sacks of PWN Golden Mandheling. If you're unsure whether you've purchased authentic PWN Mandheling, don't hesitate to ask the seller for certificates or the coffee sacks.

Why is the Triple Hand-picked Gayo Mandheling Also Called Golden Mandheling?

The triple hand-picked Mandheling that FrontStreet Coffee acquired for comparison comes from the Aceh Gayo Mountain region. Because it has undergone three strict manual selections and achieved the highest G1 grade, it is named Golden Mandheling in the market to attract public attention. In fact, through FrontStreet Coffee's cupping comparison, it lacks cleanliness compared to FrontStreet Coffee PWN Golden Mandheling, which is also related to the different coffee varieties of these two beans.

Coffee Varieties of FrontStreet Coffee PWN Golden Mandheling and Triple Hand-picked Mandheling

The triple hand-picked Mandheling uses Indonesia's most common TimTim variety, which is the Timor variety. Timor is a hybrid of Arabica and Robusta. Although its flavor is more refined than Robusta, it retains many of Robusta's rich coffee flavors, naturally lacking in cleanliness. Meanwhile, FrontStreet Coffee PWN Golden Mandheling uses the Ateng variety, which is a hybrid of Timor and Arabica, resulting in naturally cleaner flavors than the Timor variety.

How Does FrontStreet Coffee Roast These Two Mandheling Coffee Beans?

FrontStreet Coffee PWN Golden Mandheling FrontStreet Coffee roasting record: Yangjia 800N, 480g batch size. Heat to 200°C into the drum, damper set to 3. After 1 minute, adjust heat to 160°C, damper unchanged. Roast to 5'40'', temperature 148°C, bean surface turns yellow, grassy smell completely disappears, dehydration complete. Adjust heat to 140°C, damper to 4. At 9'40", ugly wrinkles and black spots appear on bean surface, toast aroma clearly turns to coffee aroma, can be defined as the prelude to first crack. At this point, listen carefully for the sound of first crack. At 9'54'', first crack begins, reduce heat to 60°C, damper set to 5, discharge at 204.5°C.

Gayo Mandheling FrontStreet Coffee roasting record: Yangjia 800N, 480g batch size. Heat to 200°C into the drum, damper set to 3. After 1 minute, adjust heat to 160°C, damper unchanged. Roast to 5'18'', temperature 148°C, bean surface turns yellow, grassy smell completely disappears, dehydration complete. Adjust heat to 140°C, damper to 4. At 8'00", ugly wrinkles and black spots appear on bean surface, toast aroma clearly turns to coffee aroma, can be defined as the prelude to first crack. At this point, listen carefully for the sound of first crack. At 9'00", first crack begins, reduce heat to 80°C, damper set to 5, discharge at 202°C.

When FrontStreet Coffee roasts these two FrontStreet Coffee Mandheling coffee beans, to highlight the rich coffee flavor inherent in Mandheling coffee beans, medium-dark roasting is used. Medium-dark roasting is generally close to second crack. Depending on the roaster, first crack occurs at approximately 180°C-205°C, while second crack occurs at 205°C-230°C.

Do Oily Coffee Beans Mean They Are Commercial Coffee Beans?

FrontStreet Coffee recently heard such an evaluation of FrontStreet Coffee PWN Golden Mandheling: "This bean has oil on the surface, so it's a commercial coffee bean." Here, "commercial bean" generally refers to coffee beans that are not of high quality, with lower quality and high defect rates. In terms of price, specialty coffee beans are several times more expensive than commercial beans. Lower quality coffee beans are often roasted dark to reduce the inherently poor flavor of commercial beans. Typically, dark roasted coffee beans have reached a degree close to second crack/already reached second crack after first crack. The deeper the roast, the more carbon dioxide is produced inside the coffee beans.

Why Do Coffee Beans Become Oily?

Coffee bean oiliness is closely related to carbon dioxide release. Dark roasted beans show a slight oil sheen after roasting is complete, then the surface begins to "oil" around the second to fifth day after roasting. This is because the lipids contained in the coffee beans, through long roasting time, high dehydration rate creates water-oil imbalance, and then large amounts of carbon dioxide are released after roasting, creating the oil phenomenon. Therefore, if dark roasted beans show surface oil during storage, this is a normal phenomenon. This also shows that the biggest cause of oiliness is the degree of roasting rather than the quality of the coffee beans. Of course, the amount of oil on coffee beans is still related to coffee varieties. For example, Robusta coffee beans contain more lipids than Arabica.

FrontStreet Coffee Cupping Comparison

Regarding the flavor performance of these two coffee beans, the biggest difference was already mentioned when discussing coffee varieties: cleanliness. FrontStreet Coffee PWN Golden Mandheling provides a thick, sweet aftertaste with low acidity and high cleanliness, while the triple hand-picked Gayo Mountain Mandheling offers high body but insufficient cleanliness, with slightly higher acidity than FrontStreet Coffee PWN Golden Mandheling.

FrontStreet Coffee Brewing Experience

This brewing aims to highlight the rich, clean, and aromatic characteristics of these two FrontStreet Coffee Golden Mandheling coffees, using a KONO Meimon cone dripper for brewing. The KONO Meimon cone dripper's rib grooves extend to the bottom of the coffee liquid outlet. Because the ribs are at the bottom and very short, and fit tightly with the filter paper, the flow rate is slower than V60, making it suitable for brewing coffees that express body. The grind size used is medium-coarse (73% passes through 0.85mm standard sieve), with 15g of coffee, and a coffee-to-water ratio of 1:15, water temperature 89°C.

After wetting the filter paper, pour in the ground coffee powder and gently level the coffee bed. Use 15 grams of coffee powder. First, pour 30 grams of 89°C hot water for blooming, with a blooming time of 30 seconds. After blooming, pour the second stage to reach a total water volume of 125 grams, using gentle circular pouring to avoid bed collapse. After pouring, let the water filter and extract slowly. When the liquid level drops to one-third, pour the final stage to reach a total water volume of 225 grams. Complete pouring around 1 minute 32 seconds, and finish extraction around 2 minutes, then remove the dripper.

FrontStreet Coffee PWN Golden Mandheling Flavor Description:

Sweet medicinal herbs, cinnamon-like spices, citrus peel notes, rich thick sweetness, creamy walnut chocolate. The fruit acidity is restrained and gentle, with strong melon aroma in the fragrance. As the temperature decreases, medicinal herb aroma emerges, with light spices, and the herbal notes provide thickness with rich sweetness.

Triple Hand-picked Gayo Mandheling Flavor Description:

Spicy herbal notes, gentle acidity, cocoa and nutty aftertaste, obvious sweetness, and high body.

Important Notice :

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