SL28 - A Kenyan Specialty Coffee Variety's Rise to Global Recognition

If you’ve had a few different coffees from Kenya, you’ve most likely had one of the variety SL28. It’s a variety that evokes images of vibrant, complex coffee. Known for its exceptional cup quality and unique characteristics, this iconic specialty coffee variety has captured the hearts of coffee drinkers around the world. But did you know that it became a specialty coffee darling back in the late 30s?

In this article, we'll take a look at the fascinating story of SL28. We'll explore its origins, its journey from Kenya to Latin America, and the qualities that make it so special.

The History and Origin of SL28

SL28 traces its roots back to the 1930s in Kenya. The British colonial government set up Scott Agricultural Laboratories (Scott Labs) in the 1920s. It was founded to do research into improving farming in the region. The lab also provided technical advice and training to Kenyan farmers on behalf of the Department of Agriculture. 

They researched a variety of crops, one being coffee. One of Scott Labs’ most significant contributions to coffee was the development of the SL varieties, including the famous SL28. The lab selected and studied 42 trees of various origins for yield, quality, and drought and disease resistance. In 1931, the senior coffee officer of Scott Labs, A.D. Trench conducted a tour of Tanganyika (now Tanzania). According to historical documents, he noticed a variety growing in the Moduli district that appeared to be tolerant to drought, diseases and pests. He collected seeds and brought them back to Scott Labs where they confirmed all these properties.

This variety was widely distributed until its offspring, SL28, replaced it. The name SL28 comes from the way that Scott Labs identified tree selections between 1935 and 1939. SL stands for Scott Labs and the number signifies the tree’s serial number.

Many consider SL28 the prize selection of this period of intensive breeding. Scott Labs selected it for its desirable combination of drought resistance, high yield potential, and exceptional cup quality. It quickly gained recognition for its ability to thrive in challenging conditions and produce coffees with a distinctive flavour profile. Recent genetic tests have confirmed that SL28 is related to the Bourbon genetic group.

Scott Labs  played a crucial role in shaping the Kenyan coffee industry. It helped give the country a reputation for producing high-quality coffee. And the research and development the laboratory carried out continues to have a lasting impact.

Cup Quality and Flavour Profile

SL28 is renowned for producing coffees with bright acidity, medium to full body, and a complex flavour profile. The cup often features notes of berries, citrus, and sometimes even wine-like characteristics. A variety of factors influence these qualities. This includes the specific terroir, the altitude, and the processing methods.

This variety is typically grown at higher altitudes which contributes to the coffee's complex flavour development. The cooler temperatures at these elevations slow down the ripening process. This allows the coffee to develop more varied flavours. Additionally, the specific soil composition and climate of the growing region can further influence the final cup profile.

It is known for its exceptional cup quality. And it consistently scores high in coffee competitions, often in the 88-90+ range (out of 100). But, it’s important to note that while SL28 is known for its potential to achieve high scores, not all SL28 coffees will necessarily score this high. The final score can vary depending on processing, terroir, and the farmer's skills.

The Spread to Latin America

Across the coffee-growing regions there is an increasing demand to improve quality and diversify crops. With climate changes, making sure that your production is resilient is any coffee farmers number one priority. This results in new varieties being developed - such as the Esperanza variety in Costa Rica - or existing varieties from other regions being introduced into new territories. So, in recent years, SL28 has made its way to Latin America. Here it has gained popularity among coffee producers and enthusiasts.

Several countries such as Honduras, Costa Rica, and Guatemala, have embraced SL28. They are now producing exceptional coffees from this variety. There are three main factors that have contributed to SL28 appearing in Latin America:

• Coffee Research Institutes: Many Latin American countries have established coffee research institutes which focus on improving coffee production. They often work with organisations and researchers to introduce new varieties and technologies.
• Progressive coffee producers: Producers such as Benjamin Paz and Evin Moreno in Honduras are always seeking to improve the quality and sustainability of their coffee. Producers like them may have sourced SL28 seedlings or cuttings from other countries.
• Government initiatives: Some governments in Latin America support initiatives to introduce new varieties. This is as part of broader agricultural development programmes.

The introduction of SL28 to Latin America is part of a broader conversation about creating a sustainable and strong future for coffee farmers. By embracing new varieties and innovative farming practices, Latin American coffee producers can continue to thrive in the global market.

Coffee has always been an important part of farmers’ livelihoods across the globe. And as we see with Scott Labs, even as early as the 30s they recognised the importance of creating a better future in coffee farming. The story of SL28 is a testament to the ongoing exploration of new varieties and flavours.

Trying this variety from two different origins is an excellent way to understand the influences of terroir. You can learn more about tasting coffee here. If you want to set up your own SL28 cupping, we encourage you to try Karimikui, Kenya, and Evin Moreno, Honduras, side by side.