SL28 (Kenya variety)

Kenyan variety selected by Scott Laboratories in the 1930s from a drought-resistant Tanzanian Bourbon. Unique profile: intense phosphoric acidity (blackcurrant), high body. Susceptible to leaf rust.

Background & Context

SL28 is one of Kenya's most celebrated coffee varieties — a drought-tolerant selection made by Scott Agricultural Laboratories (the "SL" designation) in 1935 from material traced to a single Kenyan farm (Loresho Estate in Kabete) originally believed to be derived from the Tanganyika drought-resistant variety. SL28 is now considered one of the most distinctive Arabica varieties in specialty coffee, producing the characteristic Kenyan cup profile: intense blackcurrant and cassis acidity, full body, dark fruit, tomato-like savouriness in some expressions, and exceptional complexity. SL28 requires high altitude (above 1,500m) to fully develop its characteristic acidity profile; at lower elevations, the variety's inherent quality potential diminishes. SL28 is susceptible to coffee leaf rust (Hemileia vastatrix) and coffee berry borer — a significant agronomic challenge that has prompted research into rust-resistant alternatives without SL28's quality sacrifice.

Practical Use

For specialty buyers, SL28 on a lot document from Kenya is a premium quality signal — the variety's intense blackcurrant and cassis acidity is one of the most distinctive and valued flavour profiles in specialty coffee, commanding higher prices per kilogram than Kenya AB or AA lots of mixed or unspecified variety. Roasting SL28 requires careful management to preserve its characteristic acidity without over-extracting to bitterness: light-to-light-medium development (DTR 18–21%) at drop temperatures around 200°C is the typical specialty approach. In brewing, SL28 Kenya is revelatory as filter at 92°C — the blackcurrant note unfolds over 30–60 seconds of cooling and persists through a 90-second finish. Espresso from SL28 is exceptional but polarising: the intense acidity is striking and complex but may not suit consumers calibrated to more muted espresso profiles.

Related Terms

Related terms: SL28/SL34, SL34, Kenya coffee, Altitude, Acidity.