Why is Kenyan Coffee So Acidic? What is the Kenya K72 Processing Method?

When it comes to coffee beans characterized by acidity, many people think of African coffee, with Ethiopian and Kenyan coffees being prominent representatives. However, these two countries show distinct differences in their acidity profiles. Ethiopian coffee offers a cleaner, brighter acidity, while Kenyan coffee presents a richer, more intense acidic character.

Why does Kenyan coffee possess such distinctive acidity? Besides benefiting from the country's rich natural resources, it's also influenced by the renowned K72 processing method and the primarily cultivated SL28 and SL34 coffee varieties.

Kenya's Natural Advantage

Located in East Africa, Kenya consists largely of plateaus with an average elevation of 1,500 meters. The eastern branch of the Great Rift Valley cuts through these highlands from north to south, dividing them into eastern and western sections. Along this rift stand numerous volcanoes, with the most famous being Mount Kenya, an extinct volcano. The soil here, influenced by volcanic ash, is rich in phosphoric acid, giving the coffee its abundant fruity acidity.

Development of SL Varieties

Initially, Kenya cultivated the Bourbon variety and had also introduced the Kent and Jamaica Blue Mountain Typica varieties, but none yielded ideal results. Consequently, the Scott Agricultural Laboratory was commissioned to conduct varietal selection. Over the subsequent four years, Scott Agricultural Laboratory selected 42 coffee trees from different origins, researching their yield, quality, drought resistance, and disease resistance. The selected coffee trees were all prefixed with "SL" (an abbreviation for Scott Laboratory) followed by a number, with SL28 and SL34 being among the winning varieties. Although Scott Laboratory has since been renamed to the National Agricultural Research Laboratories (NARL), the coffee variety names and numbers have been preserved.

SL28 was discovered in a region called Tanganyika (now Tanzania), and genetic testing has confirmed its relation to the Bourbon genome. SL34 was selected from a coffee estate in the Kabete region near Nairobi, Kenya's capital, and genetic testing shows its relation to the Typica genome.

Characteristics of SL28 and SL34

The cultivation characteristics of SL28 and SL34 are remarkably similar—both are high-yielding, easy to grow, and suitable for cultivation at medium to high altitudes. In terms of flavor, both possess complex and varied acidity and flavor profiles, with prominent citrus and dark plum notes.

Although the yields of these two varieties are not as high as they once were and they are susceptible to diseases like coffee leaf rust, the Kenyan government has been actively promoting high-yield, disease-resistant varieties such as K7 and Ruiru 11. However, these newer varieties cannot match the unique and rich flavor profile of SL28 and SL34, so many Kenyan coffee farmers continue to primarily cultivate SL28 and SL34.

The K72 Processing Method

Beyond the unique coffee varieties, Kenya's washed processing method is equally special. In typical washed processing, fermentation rarely exceeds 36 hours, whereas Kenyan washed processing features an extended fermentation period of up to 72 hours.

After harvesting, coffee farmers select high-quality coffee cherries through flotation, then proceed with depulping and the first 24-hour fermentation. After fermentation is complete, the mucilage is removed, followed by a second 24-hour fermentation in clean water tanks. The remaining components are then cleaned before a final 24-hour fermentation in fresh water. Finally, the beans are dried on specially designed raised beds.

With these three cycles totaling 72 hours of fermentation, this processing method is known as the Kenya 72-hour fermentation washed process, or K72 for short. The extended low-temperature fermentation allows the coffee beans to develop bright, clean, yet full-bodied acidity and flavor profiles.

FrontStreet Coffee's Kenyan Selection

Combining these factors, Kenyan coffee has gained global recognition for its distinctive and complex berry-like acidic aroma, cane sugar sweetness, and juice-like acidity, earning the admiration of coffee professionals worldwide. FrontStreet Coffee offers a selection from the Asail processing plant in Kenya's Thika region, featuring SL28 and SL34 varieties processed with the K72 washed method. When brewed, this coffee reveals cherry tomato and dark plum flavors, with bright acidity, prominent sweetness, a juicy mouthfeel, and a clean finish.

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