Arabica
SL28
Also known as: Scott Laboratories 28
SL28 is one of the most iconic and beloved coffee varieties in the world , known for its intensely fruity, juicy, and complex cup profile. It was selected in Kenya by Scott Laboratories in the 1930s and has become synonymous with the distinctive Kenya coffee flavor: blackcurrant, berry, and bright, wine-like acidity.
Key Takeaways
- SL28 is responsible for Kenya's reputation for world-class specialty coffee.
- The 'SL' prefix stands for 'Scott Laboratories,' a research station in Kenya operated by the British colonial government.
- SL28 was selected from a population that may have originated from southern Sudan or Ethiopia.
- SL28's distinctive blackcurrant and berry notes are considered the hallmark of Kenyan coffee flavor.
- SL28 has deep roots, making it drought-tolerant, which was one of the reasons for its original selection.
SL28 is one of the most iconic and beloved coffee varieties in the world , known for its intensely fruity, juicy, and complex cup profile. It was selected in Kenya by Scott Laboratories in the 1930s and has become synonymous with the distinctive Kenya coffee flavor: blackcurrant, berry, and bright, wine-like acidity.
SL28 is one of the most iconic and beloved coffee varieties in the world, known for its intensely fruity, juicy, and complex cup profile. It was selected in Kenya by Scott Laboratories in the 1930s and has become synonymous with the distinctive Kenya coffee flavor: blackcurrant, berry, and bright, wine-like acidity.
Origin
Selected in Kenya from a population originating from Tanganyika (Tanzania), possibly from southern Sudan or Ethiopia.
History
SL28 was selected by Scott Laboratories in Kenya in the 1930s from a single tree population. The 'SL' prefix stands for 'Scott Laboratories,' a research station in Kenya that was operated by the British colonial government. SL28 was selected from a population believed to have originated from Tanganyika (now Tanzania), where trees were said to have been brought from southern Sudan or Ethiopia. SL28 was selected for its drought tolerance, disease resistance, and exceptional cup quality. It became the dominant variety in Kenya and is responsible for the country's reputation for world-class specialty coffee.
Discovery
Selected by Scott Laboratories in Kenya in the 1930s from a population believed to have originated from Tanganyika (now Tanzania).
Genetics and Lineage
SL28 belongs to the Bourbon genetic group, though its exact lineage is debated. Genetic analysis suggests it may be related to the Typica group or an Ethiopian landrace. SL28 is known for its genetic distinctiveness within Kenyan coffee.
Parent Varieties
Hybrid Status: Not a hybrid. SL28 is a selection from a single tree population, not a controlled cross. It is a pure-line variety.
Growth Characteristics
SL28 is a tall, vigorous tree with bronze-tipped young leaves and large beans. It has deep roots, which contribute to its drought tolerance.
Tree Size: Tall (3 to 4 meters at maturity)
Yield: Moderate. SL28 yields less than modern varieties like Ruiru 11 or Batian but is prized for its exceptional cup quality.
Disease Resistance: Moderate. SL28 is tolerant of drought but susceptible to coffee leaf rust, coffee berry disease, and nematodes. This susceptibility led to the development of resistant varieties like Ruiru 11 and Batian.
Climate and Growing Conditions
SL28 thrives in Kenyan highland conditions at elevations of 1,400 to 2,000 meters. It requires well-distributed rainfall, moderate temperatures, and fertile, well-drained volcanic soils.
Climate Preferences: Tropical highland climate. Optimal temperatures 15 to 24 degrees Celsius. Drought-tolerant due to deep root system.
Rainfall: 1,200 to 1,800mm annually, well-distributed.
Elevation Range: 1,400-2,000 meters
Processing Compatibility
SL28 is most famous as a washed coffee, which highlights its bright acidity and blackcurrant notes. Natural processing produces intensely fruity, berry-forward cups. Honey processing is also excellent.
Roasting Behavior
SL28 beans are dense and take heat well. Light to medium roasts best preserve its bright acidity and fruit complexity. Recommended for specialty roasting.
Cup Profile
SL28 is renowned for its intensely fruity, juicy, and complex cup profile. It has bright, wine-like acidity, a juicy body, and distinctive notes of blackcurrant, blackberry, tomato, and sometimes citrus. The cup is bold, complex, and unmistakably Kenyan.
Acidity
Bright, wine-like, and intense. Often described as juicy or succulent.
High, with dark fruit and berry sweetness.
Body
Medium to full, often described as juicy or syrupy.
Professional Cupping Notes
Top SL28 lots from Kenya regularly score 87 to 92+ points in SCA cupping. Competition lots have scored above 93 points. SL28 is considered one of the world's great coffee varieties.
Common Defects
- •Susceptible to coffee leaf rust
- •Susceptible to coffee berry disease
- •Prone to potato defect in some regions
Brewing Recommendations
SL28 excels as pour over (V60, Chemex) to highlight its bright acidity and fruit complexity. Also excellent as espresso for its bold, juicy character. Recommended brewing temperature: 92 to 96 degrees Celsius.
Countries Where Grown
Notable Farms
Interesting Facts
- •SL28 is responsible for Kenya's reputation for world-class specialty coffee.
- •The 'SL' prefix stands for 'Scott Laboratories,' a research station in Kenya operated by the British colonial government.
- •SL28 was selected from a population that may have originated from southern Sudan or Ethiopia.
- •SL28's distinctive blackcurrant and berry notes are considered the hallmark of Kenyan coffee flavor.
- •SL28 has deep roots, making it drought-tolerant, which was one of the reasons for its original selection.
Frequently Asked Questions
Sources
- •World Coffee Research
- •Specialty Coffee Association
- •Kenya Coffee Board
- •Illy, A. 'Espresso Coffee: The Science of Quality' (2nd ed.)
Related Varieties
Batian
Batian was developed to combine disease resistance with the cup quality of SL28. Well-grown Batian produces a bright, juicy cup with notes of blackcurrant,...
ArabicaBourbon
Sweet, complex, and balanced. Known for a pronounced sweetness, deep fruit notes (berry, stone fruit), and bright but rounded acidity. Body is medium to full with a smooth, creamy mouthfeel. Among the most sought-after cup profiles in specialty coffee.
ArabicaK7
K7 produces a clean, balanced cup with bright acidity, medium body, and notes of citrus, berry, and chocolate. The cup is good but generally considered...
ArabicaRuiru 11
Ruiru 11's cup quality is debated. Well-grown Ruiru 11 can produce a bright, fruity cup reminiscent of SL28 but generally with less complexity and intensity....
ArabicaRume Sudan
Rume Sudan has a complex, unique cup with bright acidity, a juicy body, and distinctive notes of stone fruit, berries, citrus, and sometimes floral or herbal notes. The cup is complex, elegant, and unlike Typica or Bourbon varieties.
ArabicaSL14
SL14 produces a good-quality cup with bright acidity, medium body, and notes of citrus, berry, and chocolate. The cup is similar to other Kenyan SL varieties...
ArabicaSL34
SL34 has a rich, complex cup with a heavier body and darker fruit notes than SL28. It has bright acidity, a full, syrupy body, and notes of blackcurrant, plum, dark cherry, and chocolate. The cup is complex, rich, and less overtly fruity than SL28.
Related Encyclopedia Entries
Acidity
In coffee tasting, acidity refers to the bright, vibrant, and often fruity quality that gives coffee its liveliness and structure. Unlike the negative connotation of acidity in everyday language, coffee acidity is a desirable characteristic when balanced. It is perceived as a pleasant tartness or brightness on the palate, similar to the acidity in wine or fruit.
Sensory & TastingBody
Body, also called mouthfeel, refers to the physical weight, texture, and viscosity of coffee as it is perceived in the mouth. It is a tactile sensation rather than a taste, ranging from thin and tea-like to thick and syrupy. Body is influenced by brewing method, coffee oils, suspended solids, roast level, and the variety and origin of the coffee.
Origins & GeographyCoffea Arabica: The Specialty Coffee Species Explained
Arabica coffee (Coffea arabica) is a species of coffee plant native to the highland forests of Ethiopia and South Sudan. It is the most widely cultivated coffee species worldwide, accounting for approximately 60 to 70 percent of global coffee production. Arabica is prized for its complex flavor, refined acidity, and aromatic diversity, producing notes ranging from floral and citrus to chocolate and caramel depending on origin, variety, and processing.
Coffee ScienceCoffee Leaf Rust
Hemileia vastatrix belongs to the order Pucciniales and is an obligate biotrophic fungus, meaning it requires living host tissue to survive. The infection cycle begins when urediniospores are deposited on the abaxial (underside) surface of the coffee leaf, typically via wind or rain splash. Germination occurs only in the presence of free water—such as dew or rainfall—within a temperature range of 15°C to 28°C. Upon germination, the fungus enters the leaf through the stomata and establishes a mycelium that colonizes the internal tissue. The visual manifestation of the disease begins as small, chlorotic spots that expand into characteristic orange, powdery pustules. These pustules contain thousands of spores capable of further infection. The physiological impact includes a rapid reduction in photosynthetic capacity and the eventual abscission of the leaf. Severe cases lead to 'dieback,' where the plant's branches wither due to carbohydrate depletion, often resulting in the death of the tree or a total loss of the following year's crop.
Origins & GeographyEthiopian Coffee: The Birthplace of Arabica Coffee
Ethiopia is widely considered the birthplace of coffee, where the Coffea arabica plant originated in the highland forests of the southwest. Ethiopia remains one of the world's top coffee producers, known for extraordinary genetic diversity, distinctive regional cup profiles, and processing traditions that date back centuries. Regions like Yirgacheffe, Sidamo, Guji, and Harrar produce some of the most sought-after specialty coffees in the world, prized for their floral, citrus, and tea-like characteristics.
Coffee ScienceExtraction
Extraction is the process of dissolving soluble compounds from ground coffee into water, producing the beverage we know as coffee. During extraction, water pulls acids, sugars, lipids, carbohydrates, and melanoidins from the coffee grounds in a sequence that shapes flavor, body, and aroma.
Related Book Chapters
- •Chapter 4: Varietals & Cultivars
- •Chapter 2: Coffee Origins
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Keith E. Lyons
Author, Researcher & Coffee Educator
Keith E. Lyons is the author of The Complete World of Coffee and the publisher behind Lyons Den Publishing. A licensed trauma therapist turned specialty coffee writer, Keith blends scientific rigor with genuine passion for the craft of coffee.
Last Reviewed
August 10, 2026
Sources & References
(4)Claims are cited to verifiable sources. Peer-reviewed research is marked.
- 1World Coffee Research
- 2Specialty Coffee Association
- 3Kenya Coffee Board
- 4Illy, A. 'Espresso Coffee: The Science of Quality' (2nd ed.)
Authoritative References
Editorial Standards
- • Fact-checked against peer-reviewed coffee science research and industry standards.
- • Reviewed by the author with documented sources for every factual claim.
- • Updated regularly; the "Last Reviewed" date reflects the most recent verification.
- • Corrections are made promptly when new research or evidence emerges.
Our editorial process prioritizes accuracy, scientific rigor, and practical relevance for coffee enthusiasts and professionals alike.
Publisher
Lyons Den Publishing · Founded 2025 · San Diego, CA
Contact
lyonsdenpublishers@gmail.comIntelligent Recommendations
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SL34 has a rich, complex cup with a heavier body and darker fruit notes than SL28. It has bright acidity, a full, syrupy body, and notes of blackcurrant, plum, dark cherry, and chocolate. The cup is complex, rich, and less overtly fruity than SL28.
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Sl28 Coffee Variety
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Kenya
Kenyan coffee is known for its powerful, wine-like acidity, full body, and intense fruit flavors. Blackcurrant is the signature note, alongside grapefruit,...
Sl34 Coffee Variety
SL34 is a Kenyan selection from Kabete, often confused with SL28 but descended from a different Bourbon lineage. It thrives at slightly lower altitudes and produces a fuller-bodied cup than SL28, with the same signature Kenyan blackcurrant acidity but a heavier, more syrupy mouthfeel.
Batian Coffee Variety
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SL34
SL34 has a rich, complex cup with a heavier body and darker fruit notes than SL28. It has bright acidity, a full, syrupy body, and notes of blackcurrant, plum, dark cherry, and chocolate. The cup is complex, rich, and less overtly fruity than SL28.
SL14
SL14 produces a good-quality cup with bright acidity, medium body, and notes of citrus, berry, and chocolate. The cup is similar to other Kenyan SL varieties...
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SL17 produces a good-quality cup with bright acidity and notes of citrus and berry, similar to but generally less complex than SL28.
K7
K7 produces a clean, balanced cup with bright acidity, medium body, and notes of citrus, berry, and chocolate. The cup is good but generally considered...
Recommended Encyclopedia Entries
Reference definitions that complement this page.
Sl28 Coffee Variety
SL28 is the legendary Kenyan arabica selection from Ruiru, bred by Scott Laboratories for drought resistance and cup quality. It produces the archetypal Kenyan cup: explosive blackcurrant, citrus brightness, and a wine-like complexity that makes it the benchmark for specialty coffee worldwide.
Sl34 Coffee Variety
SL34 is a Kenyan selection from Kabete, often confused with SL28 but descended from a different Bourbon lineage. It thrives at slightly lower altitudes and produces a fuller-bodied cup than SL28, with the same signature Kenyan blackcurrant acidity but a heavier, more syrupy mouthfeel.
Batian Coffee Variety
Batian is a modern Kenyan release from the Coffee Research Institute, bred for disease resistance while preserving the cup quality of SL28 and SL34. Named after Mount Kenya's peak, it delivers bright acidity and blackcurrant notes at altitudes above 1,700 meters.
French Mission Coffee Variety
French Mission is one of the original coffee varieties planted in Kenya, introduced by French missionaries in the late 1800s. It laid the genetic foundation for Kenya's renowned SL varieties and still produces bright, blackcurrant-toned cups at high altitudes.