What is the Quality Tier of Kenyan Coffee? Why Does Kenyan Coffee Have Cherry Tomato Notes? What is the SL28 Coffee Variety?

The Remarkable SL28: Kenya's Star Coffee Variety

Just as different grape varieties produce wines with distinct flavors, coffee varieties are one of the key factors shaping the final flavor in your cup. Panama's T2722 Geisha is the perfect example, renowned for its white floral notes and citrus fruit character.

Today, FrontStreet Coffee wants to introduce another star variety with equally outstanding flavor: SL28 from Kenya. This variety contributes significantly to Kenya's famous plum flavors and bright acidity.

The Origins of SL28

SL28 is one of Kenya's most representative varieties. It is a direct descendant of Bourbon, selected and cultivated in Kenya in the early 20th century. The body responsible for that work was Scott Laboratories, where "SL" stands for Scott Laboratories and "28" is the variety's experimental number at the time.

In the 1930s, the Kenyan government commissioned Scott Laboratories to conduct coffee breeding research, aiming to find varieties that could adapt to Kenya's terroir and suit large-scale cultivation with commercial value. Between 1935 and 1939, Scott Laboratories collected 42 different varieties from various origins and studied their yield, quality, drought resistance, and disease resistance. Many varieties ultimately distinguished themselves. SL28 and SL34 emerged as the two best known, and they remain key to creating the Kenyan flavor today.

Characteristics and Spread of SL28

According to the materials FrontStreet Coffee consulted, in 1931 a senior official from Scott Laboratories discovered a coffee variety in Monduli, in northeastern Tanganyika, now Tanzania, that appeared tolerant of drought, disease, and pests. It was brought back to Kenya for study, where its drought resistance was confirmed. By 1935 the variety was put into cultivation, and it was SL28.

Beyond drought resistance, SL28 has excellent yield, flavor, and bright acidity, which made it an instant hot commodity once Kenyan authorities released it. Uganda adopted it first, and it was later cultivated by major producing countries in Central America, a sign of its remarkable popularity. SL28 does have drawbacks: like SL34, it lacks disease resistance and is susceptible to various coffee diseases.

Genetic Background and Identification

Research also shows that SL28 belongs to the Bourbon genetic group, meaning it evolved from Bourbon. That explains why its beans share Bourbon's characteristic round, small shape and are highly identifiable. Today most Kenyan coffees are blends of SL28 and SL34. Because their bean shapes differ significantly, SL34 is a Typica variant with an elongated, elliptical shape, we can easily tell the two apart in a sample of Kenyan coffee.

Tasting Experience

To date, FrontStreet Coffee has tasted SL28 from various producing countries, such as El Salvador and Costa Rica. They all show distinct blackberry acidity with very bright acid profiles. Compared with SL28 produced in Kenya, however, their texture is not as rich and full-bodied. That inevitably brings us to Kenya's unique growing conditions and processing methods, which, like the varieties themselves, are indispensable in creating Kenyan flavor.

Now that we have mentioned it, FrontStreet Coffee has to brew a pot to taste. The bean we are brewing today is FrontStreet Coffee Kenya Asalia from FrontStreet Coffee's list. It comes from the Asalia Processing Station in the Thika region, is a single-origin bean made from a blend of SL28 and SL34, and is processed using the classic Kenyan washed method.

Coffee Details

FrontStreet Coffee: Kenya Asalia

Region: Thika

Processing Station: Asalia Processing Station

Altitude: 1550~1750 meters

Varieties: SL28, SL34

Processing Method: Washed

Flavor Notes: Black plum, cherry tomato, brown sugar

Brewing Impressions

This bean already reveals distinct black plum and cherry tomato aromas when ground. As hot water is added, the coffee begins to give off brown sugar sweetness. After brewing, the first sip shows very rich acidity with dominant flavors of black plum, cherry tomato, and plum, accompanied by noticeable brown sugar sweetness and a subtle oolong tea aftertaste. The mouthfeel is round and full-bodied, making for a comfortable, enjoyable drink.

FrontStreet Coffee Recommendation

Variety shapes flavor, and as the opening comparison suggests, no variety has built a reputation quite like Geisha. The name comes from the English spelling "Geisha," and it became a favorite among Arabica varieties for its distinctive florals and superb sweet-tart balance. Panama is where it made its name, helped by high altitude, microclimate, and soil, after the owner of Hacienda La Esmeralda discovered it and entered it in the Best of Panama competition, where it stunned the judges with an average cupping score of 94.6 and set a BOP record.

Hacienda La Esmeralda's Geisha line is split into Red Label and Green Label. The Red Label is officially named "Esmeralda Special," grown at 1600-1800 meters, with every batch scoring above 90 points in cupping and each batch carrying its own number, all from a single plot. The Green Label, officially "Private Collection," blends batches from several plots to express the estate's signature high-altitude Gesha flavor at a more affordable price. For a first taste of the famous Geisha profile, FrontStreet Panama Boquete Gesha is the entry-level pick, delivering the classic citrus-honey character, an oolong-tea finish, and delicate fruit acidity at a friendly price.