Our new Sumatra is a Giling Basah? So the logically follow up I received was: what is Giling Basah?
Also known as wet-hulling, Giling Basah is a traditional method for processing coffee in Indonesia. Akin to other approaches, the goal is to take the coffee cherry and remove its many layers: skin (exocarp), the mucilage (mesocarp), and the parchment (endocarp). After pulping the outer peel, fermentation in tanks helps break down the pectin that anchors the remaining sticky layers. Times vary according to approach and region, but typically a day after fermentation, a wash will strip away the mucilage leaving just the parchment.
For most coffees, the next stop is drying beds. Take for example, our Ethiopia Yurkro. It spends 8 plus days on beds as water evaporates from the parchment. Part of the reason the Yukro has such delicate intensity is the use of shaded canopys during the initial 24-28 hours to prevent cracking under the intense Ethiopian sun. The end point for this method leaves a stable and mold-resistant moisture content of about 10-12%.
However in Sumatra, such timelines would simply not work do to the dominant rainfalls and ubiquitous humidity. On beds, it could take up to 4 weeks, which endangers a plethora of harmful molds and bacterial defects. The solution: remove the parchment much sooner. At a 20-24% moisture level or 2-3 days, the inner bean is exposed to air at special mills designed to handle the semi-dry parchment. At Reje Gayo, the beans then dry in the sun during the day and further ferment in bags overnight. The system aligns perfectly with the unique climate and gives Sumatran coffee those hallmark flavours. The causes for which are still relatively unknown but common belief is that it is due to ambient yeasts and bacteria specific to the region.
As I frequently repeat here, coffee terroir is complicated and multifaceted. There is a political dimension given the method originates with Dutch colonialism. The motivation was profit, not quality. Shorter timelines translated to quicker exports and larger margins. There is an industry dimension, given low-acid and high-body cups are not exactly celebrated in most third wave shops. Yet, Indonesian crops were integral to the spread of the classic ‘mocha java’ blend. There is an element of approach. Slightly higher moisture can present a challenge for roasters. Unfortunately meaning Sumatrans cups often undersell their origin.
And, of course, there is taste. At the cupping table this week, there was unanimous admiration of Reje Gayo for defying the usual associations of deep, spicy, and earthy flavours. Typically if a cup presents any of these notes, it is dry or bitter. But in a great Sumatra it is full, creamy, and deeply satisfying. Pumpkin pie is on the bags for a reason.
tl;dr: Giling Basah is a unique processing method that pulps parchment before full drying.