The Story of Sumatran Coffee: Mandheling Coffee Bean Processing Methods and How to Brew Delicious Pour-Over Coffee

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Understanding Wet-Hulled Processing: Sumatra's Unique Coffee Method

Previously, we recommended Sumatran Mandheling coffee, and many friends were curious about the "wet-hulled processing method," wondering how it differs from traditional washed and natural processing methods. While we've explained the specific processing methods before, today we'll systematically explore the origins and evolution of wet-hulled processing.

Sumatran coffee captivates with its enchanting cedar and herbal notes, unique spice flavors that make it truly distinctive. But do you know the actual growing environment of this one-of-a-kind coffee on the world coffee map? Sumatra Island lies on the equator, with most of the island covered by tropical rainforest. The annual humidity ranges from 70%-90%, with yearly rainfall reaching 2000mm. Although the volcanic ash soil allows coffee trees to grow vigorously, this humid climate easily causes coffee cherries to mold and rot.

Due to the high year-round humidity, following normal washed processing methods, drying time would be double that of regular processing methods. If coffee beans are not dried promptly within a short period, they can easily over-ferment or develop mold. Each change affects the coffee's flavor profile. Therefore, how to process coffee cherries and preserve coffee beans has become the biggest challenge in Sumatran coffee production.

How Sumatrans Smartly Produce Coffee Beans

Let's look at how Sumatrans intelligently produce their coffee beans:

Step 1: Remove the outer pulp of the coffee cherry, keeping the parchment and mucilage, and place them in concrete tanks or plastic barrels for overnight fermentation. This helps decompose the mucilage, making it easier to remove.

Step 2: Wash the coffee cherries. The mucilage will be removed during this washing process, giving us coffee beans with only the parchment. These are dried in the sun for 2-3 days until their moisture content drops to 20-24%, allowing the coffee beans to reach sufficient hardness to separate from the parchment.

Step 3: At 20-24% moisture content, the coffee beans themselves are soft and still contain considerable moisture, while the parchment is semi-dry. However, Sumatra's humid climate no longer allows for further drying. At this point, machines are needed to separate the parchment from the coffee beans. In this condition, removing semi-dry parchment often cannot be done completely, always leaving some residue. Each additional pass of hulling risks damaging the coffee beans, creating Sumatra's characteristic "elephant beans" (damaged beans). This is why the Mandheling green coffee beans you purchase often have some inconsistency.

Step 4: Continue drying these unevenly hulled coffee beans until moisture content drops to 12-13%. During the day, these coffee beans enjoy the sunshine, while at night they're stored in burlap bags, continuing to ferment under the influence of moisture. When drying is complete, these coffee beans can be taken away by buyers.

The above steps represent the complete wet-hulled processing method. Compared to other processing methods, wet-hulled processing is a race against time, with the ultimate goal of minimizing drying time in high-humidity air.

The Importance of Manual Bean Sorting

Of course, there's another crucial key that cannot be overlooked: manual bean sorting. Good Mandheling coffee often undergoes three rounds of manual sorting. Under such humidity-resistant processing methods, Sumatran coffee beans show inconsistency. This is where hardworking Sumatrans ensure we drink high-quality Mandheling coffee. Think about your own bean sorting during roasting, while they face an entire season's production, all to bring you a cup of high-quality Mandheling coffee.

We can see that wet-hulled processing allows for rapid coffee cherry processing, and the reason for pursuing this speed is Sumatra's high humidity and heavy rainfall, leaving coffee farmers with no other choice.

The following charts compare rainfall and number of rainy days between Sumatra and Sidamo regions in 2016.

2016 Rainfall Data Comparison

2016 Sumatra Region Rainfall and Rainy Days Chart

2016 Sidamo Region Rainfall and Rainy Days Chart

Looking at the vertical axis units, we can clearly see Sumatra's extremely high rainfall, far surpassing Sidamo. Under such harsh conditions, coffee bean processing is a race against time, against rot and bacterial infection. Perhaps Sumatran coffee doesn't appear as refined as other coffees, but believe me, when it travels across oceans to reach you, it comes with sincerity and high quality.

Recommended Sumatran Coffee Bean Brands

FrontStreet Coffee's roasted Sumatran coffee - [Golden Mandheling Coffee] offers full assurance in both brand and quality. More importantly, it offers exceptional value - a 227g package costs only 89 yuan. Calculating at 15g per cup, one package makes 15 cups, costing only about 6 yuan per cup. Compared to café prices that often reach dozens of yuan per cup, this is truly a conscientious recommendation.

FrontStreet Coffee: A roastery in Guangzhou with a small shop but diverse bean varieties, where you can find both famous and lesser-known beans, while also providing online services. https://shop104210103.taobao.com

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473