Complete Process and Operation Steps of Wet Hulling Coffee Bean Processing_Sumatra Mandheling Coffee Bean Wet Hulling Method

Professional coffee knowledge exchange and more coffee bean information, please follow Coffee Workshop (WeChat public account: cafe_style)

The wet-hulled processing method for coffee beans is a tradition in Sumatra, Indonesia. According to the chairman of the Indonesian Specialty Coffee Association (SCAI), it's called "Semi-washed Wet hulled." Here are the specific operational steps broken down:

Step 1: Harvesting

March to May and September to December are the harvest seasons for Sumatran coffee, where each farmer harvests coffee cherries. With the promotion of specialty coffee and the implementation of the Full Red Cherry Program, more and more coffee farmers now only harvest fully red coffee cherries.

Step 2: Depulping and Fermentation

Every day after noon during the harvest season, coffee farmers send the coffee cherries collected in the morning to depulping workshops for processing. This involves removing the fruit skin and pulp from the coffee cherries, turning them into wet parchment coffee.

Sumatra's natural environment is superior, and most of the water used here comes from mountain springs.

Farmers ferment the parchment coffee, typically for 12-36 hours depending on specific conditions. After fermentation, the parchment coffee is dried. During harvest season, every household has sacks spread out in front drying parchment coffee - this is their source of coffee income.

The removed fruit skins and pulp are fermented into fertilizer. Plantations using such ecological fertilizers receive extra points when applying for organic coffee plantation certification.

Step 3: Hulling and Drying

When the moisture content of the parchment coffee reaches 35-40%, farmers collect them into woven bags, either 40kg or 80kg per bag, and send them to coffee processing factories for hulling.

In recent years, Sumatra has seen an increase in certified coffee varieties. Typically, these processing plants handle certified coffees - organic, fair trade, UTZ, etc. - separately. After hulling, these green beans are also placed separately in bags to avoid mixing different coffees.

The moisture content of these coffee beans is usually higher and requires continued drying to about 15% moisture.

Step 4: Machine Sorting and Hand Sorting

When the coffee beans are dried to 15%-14% moisture, they undergo machine sorting to remove impurities and classify by particle size. This step is typically done by machine, hence the name "machine sorting."

To improve quality, machine-sorted coffee is sent to hand-sorting warehouses for further classification. Workers use sharp vision and dexterous hands to pick out two types of defective coffee beans.

In countries with higher labor costs, large amounts of manual labor cannot be used for coffee sorting. To ensure quality, they can only purchase expensive machines and high-quality color sorting equipment to replace manual labor for quality control.

Wet-hulled coffee beans create the unique coffee flavor of Sumatran coffee. Although some new processing methods have been tried, I personally prefer that Sumatra continues to use the wet-hulling method, as this can more fully stabilize the product quality.

FrontStreet Coffee: A roastery in Guangzhou with a small storefront but diverse bean varieties, where you can find both famous and lesser-known beans. Online shop services are also available. 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