Traditionally, Kenya’s coffee is renowned for its vibrant acidity and rich body, characteristics enhanced by the country’s long-standing use of the wet (or washed) processing method. This process involves pulping the cherries and then washing them with large volumes of water before drying. While effective in producing clean and consistent cup profiles, the wet process is water-intensive and does not always yield the complex flavour variations increasingly sought after in specialty coffee markets.
In recent years, evolving consumer preferences and market demands have driven innovation in coffee processing techniques. Globally, there is a growing appetite for coffee with unique, traceable, and exotic flavour profiles. As a result, Kenyan coffee growers are increasingly experimenting with alternative processing methods that offer new flavour experiences and respond to challenges such as water scarcity and distance from wet mills. These emerging methods include natural processing, carbonic maceration, anaerobic fermentation, and honey processing.
Natural (Dry) Processing
Natural processing is one of the oldest coffee processing techniques, now gaining renewed attention in Kenya. In this method, whole coffee cherries are dried in the sun without being pulped or washed. Before drying, cherries are typically floated in water to remove damaged or low-quality fruits and are then carefully sorted. The drying process can take up to three weeks, depending on climatic conditions. During this time, the sugars and flavours from the fruit penetrate the bean, resulting in a coffee with fruity, wine-like notes and increased body. This method is particularly suitable for regions facing water scarcity and farmers who lack access to wet mills.
Carbonic Maceration
This highly controlled and experimental technique originates from winemaking. It involves placing freshly harvested coffee cherries in sealed tanks filled with carbon dioxide. The absence of oxygen creates an anaerobic environment that allows specific microbial activity to flourish. These microbes ferment the sugars in the cherries in a unique way, often producing coffee with strikingly vibrant, fruity, and floral characteristics. Although still new to Kenya, carbonic maceration is gaining interest among high-end specialty coffee producers looking to create unique, limited-edition lots.
Anaerobic Fermentation
Similar to carbonic maceration, anaerobic fermentation involves processing coffee in an oxygen-free environment. However, the cherries or depulped beans are usually placed in sealed tanks without added carbon dioxide. The oxygen-deprived conditions encourage the growth of lactic acid bacteria, which break down sugars and mucilage in distinctive ways. This method can yield coffees with complex acidity, layered flavours, and a creamy mouthfeel. Temperature and fermentation duration are carefully monitored to control flavour development.
Honey Processing
Honey processing offers a middle ground between natural and washed processing. In this method, coffee cherries are pulped to remove the skin but not washed, leaving varying amounts of mucilage—the sticky layer surrounding the bean—on the parchment during drying. The proportion of mucilage retained determines the sub-category of honey process:
- White Honey: 10–15% mucilage
- Yellow Honey: 15–50% mucilage
- Red Honey: 50–90% mucilage
- Black Honey: 90–100% mucilage
As the mucilage ferments and dries on the bean, it imparts sweetness, body, and acidity, with each sub-category delivering a different cup profile.
These emerging processing methods offer both flavour diversity and practical benefits for farmers. They enable value addition at the farm level, particularly for producers who operate far from central processing facilities or in areas where water resources are limited. However, it is crucial for farmers to identify and secure committed buyers before adopting these methods. Without proper market linkage, the coffee may be categorized as low-grade and sold at reduced prices, negating the potential benefits of these innovative techniques.
