Flores Island - Tuang Coffee, Experimental Thermal Fermentation, Indonesia | Anaerobic Natural FSC-8463

-----

Location:	Manggarai, East Nusa Tenggara
Producer	Tuang Coffee
Varietal:	Yellow Caturra, Typica, Kartika
Process:	Thermal Fermentation // Anaerobic Natural
Altitude:	1400 - 1700
Production/Harvest Date:	2026
Cup Score:	86.5
Cup profile:	Orange, peach, mango, caramel, black pepper, dark chocolate.

Tuang Coffee comes from Ruteng in the Manggarai region, Flores Island, and Nusa Tenggara in Timur, Indonesia. It started in 2014 when Andre Tuang decided to leave his job in Jakarta and head to Flores to work with farmers in Flores Manggarai. Before then it was rare to find coffee in that area that was not mixed with coffee from other regions like Sumatra, Java, or Toraja. Coffee was exported as commodity grade while farmers were under appreciated. They suffered from limited market access and unfair payment systems. Also few people cared about specialty coffee processing.

By 2023, the organisation has more than 2500 members delivering to 17 community leaders within these farmer groups. Our coffees come from 3 main village areas of Nati, Mbohang and Gulang which have around 250 farmers. Farmers are trained every season on when and how to pick their cherries for maximum quality. Tools are provided such as grass cutters, that encourage farmers not to use any herbicides, and pruning scissors and gloves. Financial support is also provided with a pre-harvest deposit or a bonus after the season.

Tuang are also helping to provide in some areas deposits for farmers to help them build their own homes which they will repay with coffee over the following harvests. They grow yellow caturra, typica and kartika traditionally on the farms as well as ginger and clove and the farmers see ginger as 'money in the ground' as they are able to harvest this monthly to sell for cash when needed. Coffee grows here in very healthy conditions. Trees are well spaced from one another.

Farmers use dried grass, leaves, and pulped cherry skins as organic fertilizer. Pruning is carried out only when needed and shade trees are grown around the coffee areas. Cherries are picked by farmers in the Villages and then sent for processing in Ruteng at the Tuang central processing site. 

Thermal fermentation process: 

The process begins by harvesting the cherries at peak ripeness to ensure maximum sugar content.

Next, a thermal stage is introduced, involving a brief exposure to high temperatures of around 70 °C. During this phase, the coffee cherries are pulped and placed in direct sunlight. The heat exposure starts breaking down the natural sugars, partially caramelizing them and enhancing malic and lactic acidity. This contributes to greater complexity and a more pronounced fruit character in the final cup.

The coffee is then thoroughly mixed and transferred into a hermetically sealed tank. Proper sealing is essential, as any escape of CO₂ would prevent pressure from building. Fermentation takes place over 18 to 23 hours, with the tank temperature carefully controlled. After approximately 15 hours, pH levels are regularly monitored to track the fermentation progress.

Fermentation must be halted once the sugars in the mucilage are fully consumed, but before any alcohol develops. During this stage, the CO₂ generated creates pressure inside the tank, helping drive the coffee’s natural flavors into the parchment.

Finally, the tanks are carefully opened, the coffee is drained—at this stage the mixture has become more fluid—and it is then dried under the sun.