Wet-Hulled coffee, known also as semi-washed, Sumatra process, or giling basah, is a distinctive post-harvest processing technique prevalent in Indonesia. This method is particularly suited for regions with high humidity, enabling coffee to dry effectively in damp and cloudy conditions. In this article, we delve into the Wet-Hulled process as practiced in the Gayo Highlands of Aceh, Sumatra, a region renowned for its unique coffee profile.
Table of Contents
Understanding the Wet-Hulled Process
The Wet-Hulled process begins similarly to other coffee processing methods, with the depulping of the coffee cherries. This initial step involves mill workers de-pulping sacks of coffee cherries, a process conducted as soon as possible to maintain the coffee’s quality.
Indonesia Coffee Cherry Processing – depulping
depulped-coffee-beans
The de-pulped seeds, still covered in their mucilage, are then placed in a fermentation tank overnight. This controlled fermentation is a distinctive feature at most of the Sumatra Coffee Mill, where there is oversight over each step from start to finish.
Coffee-fermentation-tank
Pre-Drying: Preparing for Wet-Hulling
Before the coffee can undergo Wet-Hulling, it requires a quick pre-drying phase. The seeds are raked into thin layers and left to dry for several hours to a full day, depending on the prevailing humidity and cloud cover. This pre-drying is crucial, as it reduces the seeds’ moisture content to about 30–35%, making them ready for the Wet-Hull process.
coffee pre drying
Wet-Hulling: The Core of the Process
The essence of Wet-Hulling lies in removing the parchment layer from the coffee seeds before they are fully dry. This contrasts with other methods where the parchment remains on the seeds until they are ready for export. The Wet-Hulling machine, similar in operation to a depulper but calibrated differently, removes the parchment layer efficiently.
Wet Hulling Machine
wet hulled coffee
In regions with less humid climates, the parchment serves to protect the coffee seeds against moisture and temperature fluctuations. However, in Indonesia’s humid and cloudy environment, removing the parchment early allows for more effective drying. Despite its benefits, Wet-Hulling is somewhat traumatic for the seeds, often resulting in some being chipped, crushed, or split.
Post-Hulling Drying and Final Preparation
Once Wet-Hulling is complete, the coffee seeds, now green coffee beans, are further dried. The seeds are spread out on tarps on concrete and raked into thin layers. This drying process exposes the seeds to sunlight, heat, and air, which are critical for drying in Indonesia’s humid climate. The unique earthy, savory, and herbaceous flavors characteristic of Indonesian coffees, particularly those from Sumatra, are largely attributed to this processing method, alongside the specific cultivars and regional climate.
coffee drying final stage – on concrete
The final stage involves drying the coffee to a moisture content of 11–12%. The dried coffee is then bagged and stored in a warehouse until it is ready to be shipped. This meticulous process ensures that Wet-Hulled coffee retains its distinctive profile, making it a sought-after product in the global coffee market.
Get wet-hulled green coffee beans from us!
Email us at info@specialtycoffee.id or WhatsApp at +62 811 6380 606
