Giling Basah or semi washed or wet hulled is the Ketiara preferred post harvest processing method. This method is commonly used to process arabica coffee in Indonesia. Sumatra, Sulawesi, some parts of Java, and Gayo use the same method. Below is a step by step on how giling basah is used for post harvest processing in Ketiara.
Coffee cherry harvesting and depulping
Harvest only red cherries in the morning until late afternoon. After coffee cherries are picked and hand-sorted, they must be depulped within 18-24 hours whether at the farm, house, or at the communal pulping station. Cherries past the 24-hour mark without being depulped are not accepted in the Ketiara quality requirement. Depulping is the process of separating the coffee seeds from the outer layer of flesh.
Depending on the geographical condition of each villages, Ketiara accepts two methods of fermentation process. First main method, depulped cherries are put inside plastic burlap bags tied tightly for no longer than 24 hours. Second method – only when first method is not possible for example during peak harvest –depulped cherries are put inside a cement tank and submerged with very shallow clean water for no longer than 48 hours. The water inside the tank should be kept clean during the process. Usually within 24 hours, water need to be replaced 3-4 times. Once it is finished, then all beans need to be washed clean thoroughly to stop the fermentation process.
Fermentation is a very critical process, to accentuate the body and flavor of the coffee beans. The coffee beans ferment in the mucilage that is left on the bean after the depulping process, transforming the natural sugars to liquid.
Sun drying and wet hulling
No machines are used for the drying process even when there is no sun. First stage sun drying is done at farmer household level to achieve 30-40% of moisture level. The time to achieve this level may takes only several hours but sometimes will need 2-3 days depending on the sun. Once it is completed, we name the bean as gabah (parchment). Next stage is wet hulling. Gabah with 30-40% moisture are transported to the wet-hulling facility. Ketiara has several smaller facilities in some villages, beside the largest facility located at the main factory. Once gabah passes physical inspection, it is recorded, and directly hulled. Once it is hulled, we continue with second stage sun drying to achieve 12-13% moisture content. Once all the processes are completed, the name is no longer gabah, but green asalan.
Series of sortation (density, hand sortation, and destonner)
First the density machine. Density sortation is to remove very dense rocks and stones, and also any debris. The cooperative uses a densiometric table to separate the coffee into three or more densities. We then continue with hand sortation process. Ketiara implements the SCAA standard quality for defects. Hand sortation is to remove primary defects and secondary defects. Ketiara quality standard for specialty grade, need 3 rounds of hand sortation. We then continue with a second pass of the density machine to achieve better densities and removal of debris. Final sortation process is a destonner machine which is to remove any remaining stones and other foreign material.
Green bean analysis and blending
Each batch of arrival is analysed by Ketiara quality team for moisture, color, defect, and cup profile. All information is recorded, and used for the final process: blending. Ketiara has 6 main brands like Ketiara Sumatra Classic Mandheling, Queen Ketiara, and several private label products. Each brand has its expected standard profile. Blending is used to achieve this expected profile, which is very hard to create from a single origin due to local conditions where coffee is produced by thousands of farmer, with different arabica cultivar, at different altitude, and a processing style/ stages that depend on the weather condition. Profile is maintained through blending process.