Burundi: Nemba Anaerobic - Kayanza - Red Bourbon
In the cup: Complex and layered, tones of stone fruit, vanilla and mango yoghurt and a sherbet like effervescence, undertones of jasmine and citrus fruits.
Cupping Score: 88
Mouthfeel: Round, layered.
Variety: Red Bourbon
Process: Anaerobic fermentation with Cima yeast
Producer: Local Smallholders / Nemba Washing Station
Altitude: 1700 - 1800 meters above sea level
There are 3,113 smallholders living around Kayanza, Burundi who deliver their cherry to Nemba Washing Station
Nemba station lies in the northern province of Kayanza. Each washing station is managed and led by an agronomist. This agronomist oversees the implementation of good agricultural practice and farmer education. They collaborate with the producers to ensure they have access to the necessary farming tools. The agronomist also helps farmers determine and implement the practices best suited to the specific growing conditions of their farming plots.
Nemba uses a monitoring system to ensure traceability all along the production and processing chain. All 3,000+ producers are smallholders who own an average of 150 coffee trees. The farms delivering cherry to Nemba are all located around 1,700+ meters above sea level, near the Kibila forest. The washing station has over two hundred drying tables and can process up to 750 metric tons of coffee cherry annually.
Nemba also participates in a number of farmer outreach and support projects including a goat and pig project, Farmer Hub, strengthening cooperatives and distributing fertilizer and coffee trees.
Many trees in Burundi are Red Bourbon. Because of the increasingly small size of coffee plantings, aging rootstock is a very big issue in Burundi. Many farmers have trees that are over 50 years old, but with small plots to farm, it is difficult to justify taking trees entirely out of production for the 3-4 years it will take new plantings to begin to yield. In order to encourage farmers to renovate their plantings, Bugestal purchases seeds from the Institut des Sciences Agronomiques du Burundi (ISABU), establishes nurseries and sells the seedlings to farmers at or below cost. At the washing station, farmers can also get organic fertilizer derived from composted coffee pulp.
Despite the ubiquity of coffee growing in Burundi, each smallholder producers a relatively small harvest. The average smallholder has approximately 250 trees, normally in their backyards. Each tree yields an average of 1.5 kilos of cherry so the average producer sells about 200-300 kilos of cherry annually.
Anaerobic fermentation is a processing method where the coffee is processed in a fully sealed and oxygen deprived fermentation tank.
After selective handpicking of fully ripe cherries, they are checked in water basins to sort out underripe floaters. Coffees enter the anaerobic process in depulped cherries (honey). The beans are placed in air-sealed barrels or stainless steel tanks that need to be in a cooler environment (wind or even fridges), as the fermentation process creates heat.
After around 18-24 hours, the anaerobic process has started causing a breakdown in the mucilage and a buildup of CO2 pressure in the tank. This pressure forces the flavours of the juicy mucilage into the coffee parchment. Pressure is released through one-way valves at the top of the barrel - or oftentimes released through pipes that surpass water basins. The anaerobic fermentation has many levels and can take up to 120 hours, sometimes even 240 hours.
The types of microbes able to survive and participate in fermentation is limited by the lack of oxygen. The result is a very expressive flavour profile that oftentimes has notes of cinnamon, bubble gum or poached pear.
Once carefully removed from the tank, the coffee is dried to ensure a halting of the fermentation stage. This experimental process yields unexpected and complex flavours, while also giving the producer great control over the sugars, temperature, pressure, pH and length of the ferment.