The parchment coffee on the patio at Pak Jomin’s house is still wet. It is not damp. It is not dewy. It is wet, with a moisture content of about forty percent, which is approximately thirty percent higher than parchment would be at the same stage anywhere else in the world. The beans have a faint blue-green cast. They smell vegetal. They are, at this point in the process, completely unlike anything else in the global coffee trade.
This is giling basah — wet-hulling — and it is the reason Sumatran coffee tastes the way it does.
“The other countries dry to eleven percent,” Pak Jomin says, sliding a rake through the pile with the kind of casual precision that takes decades to develop. “We hull at forty. Then we dry. The taste comes from this.”
A process that should not work
The conventional wisdom, almost everywhere else in the coffee-growing world, is that parchment protects the bean during drying. You leave the parchment on until the coffee is at ten or eleven percent moisture, then you mill it off in a dry environment, usually just before export. This produces a coffee that is clean, consistent, and predictable.
Giling basah does approximately the opposite. The coffee is depulped at the farm, fermented briefly, and partly dried, often on a tarp beside the farmer’s house. Then, while it is still visibly wet, it is hulled at a collection point — the parchment stripped off the still-soft bean — and the naked green coffee is dried further, sometimes on another tarp at a second location, before being delivered to an exporter who may dry it a third time in Medan.
The bean is exposed to moisture, humidity, and a changing microbial environment during a stage at which almost every other coffee-producing country keeps it sealed in parchment. The result should be, by any reasonable theory, a catastrophe. Instead it is one of the most distinctive coffees in the world: low acid, heavy-bodied, herbaceous, earthy in a way that some people find almost meaty and others find deeply calming, with the kind of cedar-and-tobacco finish that pairs well with cold weather and long conversation.
“You cannot drink a Sumatra and expect a Kenya,” Pak Jomin says, amused by the idea. “You can only drink a Sumatra and expect a Sumatra.”
Why this method exists
The practical explanation for giling basah is, like most things in Sumatra, a combination of geography, weather, and economics. The highlands around Lake Toba are humid nearly year-round. The rainy season is not a season so much as a baseline. Drying coffee in parchment to eleven percent, under these conditions, is extremely slow and extremely uncertain — you lose lots to mold, you lose weeks to overcast skies, you lose money either way.
Wet-hulling is faster. It lets the farmer convert wet cherry to sellable green coffee in a matter of days rather than weeks, on a cash-flow cycle that actually functions in a region where most farms are small and most households have no savings cushion. The farmer sells partly-dried parchment to a collector who does the final drying. The collector sells to an exporter who polishes and grades. Risk is distributed across the chain. No single actor has to hold inventory for long.
The method evolved, in other words, because the alternative was not viable. That it produces a flavor profile that has become iconic is, in some sense, an accident of climate — an accident that the rest of the world has spent eighty years failing to replicate by any other route.
The future, which is also the past
There are, in recent years, a small number of farms in the Gayo and Lintong regions experimenting with fully washed and natural processes, aimed at the specialty export market. The coffees are excellent. They sell well. They taste, interestingly, very little like Sumatra.
Pak Jomin has tried one. He thought it was fine. He was not tempted.
“That is coffee from Sumatra,” he said, when I asked. “This” — meaning the wet-hulled lot on his patio — “is Sumatran coffee. The second one is a harder thing to make. We will keep making it.”
The patio dries in the afternoon. The vegetal smell gives way, gradually, to something darker and sweeter, like damp wood and cocoa. In the kitchen, Pak Jomin’s wife is preparing coffee the local way — ground very fine, boiled briefly in an open pot with a thumb of palm sugar, poured into small glasses and topped with a splash of cold water to let the grounds settle.
It is, predictably, delicious. It tastes, very specifically, like Sumatra.