What is the Wet Hulled Process?
The wet-hulled process, also known as Giling Basah in Bahasa, is a hybrid coffee method used in parts of Indonesia, especially Sumatra. It is a unique process that results in a distinct, low-acid, earthy, heavy-bodied coffee with a dark, opal-green colour and little silverskin clinging to the bean.
The process begins with the farmer picking ripe coffee cherry, pulping off the skin, and either drying it immediately for one day, or letting it sit overnight in a bucket with or without water. Then, the coffee is washed and partially dried with some or all of the mucilage still clinging to the parchment-covered seed. The partially dried coffee is then sold at a local market to a coffee processor.
When the coffee processor receives the wet parchment coffee, it has a moisture content of 40-50%, which is much higher than the standard moisture content for export-quality coffee. The processor then dries the coffee to a moisture content of 25-35% and runs it through a wet-hull machine. This machine uses friction to strip off the parchment, and the bean emerges swollen and whitish-green.
After wet-hulling, the coffee is dried on the patio until it reaches a moisture content of 11-14%, ready for sorting, grading, bagging, and export. The wet-hulling process shortens the drying time for the coffee, which can be advantageous in a humid climate like Indonesia's.
The wet-hulled process is controversial among coffee professionals. Some appreciate its unique flavour profile and the shorter drying time, while others criticise the method for producing inconsistent quality and not allowing the coffee to fully develop its flavours. Nonetheless, wet-hulled coffee remains popular in Indonesia and is exported all over the world, particularly to the United States and Europe.