Wet-hulled (Giling Basah)
Processing method unique to Sumatra (Indonesia): coffee is depulped and partially dried to 25-35% moisture, then the wet parchment is mechanically hulled. Result: irregularly shaped beans, very thick body, earthy and woody notes characteristic of Sumatra Mandheling.
Background & Context
Wet-hulled processing, locally called giling basah, is the defining post-harvest method of Sumatra and parts of Sulawesi and Flores in Indonesia. Unlike washed or natural processing, wet-hulling involves removing the parchment layer from coffee seeds while they still contain high moisture, typically 25-35 % water content, rather than waiting until the seed has dried to 10-12 %. The wet parchment is stripped by a hulling machine, leaving a naked green bean that continues to dry exposed directly to air. The result is a porous, swollen bean with a distinctly blueish-green colour and an earthy, full-bodied cup profile characterised by notes of dark chocolate, cedar, tobacco, and low acidity.
Practical Use
When sourcing Sumatran coffees, buyers encounter wet-hulled lots under regional identity names, Mandheling, Lintong, Gayo, rather than as a processing label. Understanding giling basah explains why Sumatran coffees taste the way they do: the porous bean structure absorbs ambient aromas during the open-air drying phase, and the absence of the protective parchment layer during final drying allows microbiological activity that contributes earthiness and body. For espresso blends, a wet-hulled Sumatran adds syrupy body and low-acid depth that balances brighter East African or Central American components. In filter brewing, the earthiness can be intense, grinders should be calibrated coarser than for washed coffees of equivalent origin weight.
Related Terms
Wet-hulled / giling basah connects to washed process, natural process, processing method, and Sumatra coffee. Key quality indicator: well-executed giling basah produces clean earthiness and body without off-flavours of mould or excessive fermentation. Related terms include parchment, moisture content, hulling machine, and green bean density.