Kenya Coffee Beans: SL28, AA Grade & Flavor Guide

Kenya produces some of the world's most complex and sought-after coffees. The distinctive blackcurrant, tomato, and bright citrus notes found in Kenyan coffee are unlike anything from other origins — and understanding why requires a look at its unique varieties, processing, and grading system.

The SL28 and SL34 Varieties

Kenya's coffee reputation is built largely on two varietals: SL28 and SL34. According to World Coffee Research, these are selections made in the 1930s by Scott Laboratories (hence "SL") from seeds sourced in Tanzania and Sudan.

SL28 is considered the finer of the two, producing coffees with intense blackcurrant and phosphoric acidity when grown at altitude. It performs best above 1,600m. SL34 is more productive and slightly less complex in flavor, but still delivers the characteristic Kenyan brightness.

Both varieties are highly susceptible to coffee leaf rust, which has led Kenya to develop drought-resistant hybrids like Ruiru 11 and Batian — though these generally lack the cup quality of SL28/SL34.

Kenya's Grading System

Kenya uses a screen-size-based grading system. The most common grades you'll see are:

Grade	Screen Size	Notes
AA	6.75mm+	Largest bean, most uniform roasting
AB	6.00–6.75mm	Blend of A and B grades
PB (Peaberry)	Round single seed	Often prized for concentrated flavor
C, E, TT	Smaller sizes	Lower market grades

Double-Fermentation Processing

Kenya is known for its unique two-stage wet (washed) processing. After the cherry skin is removed, beans are fermented underwater for 24–72 hours (first fermentation), washed, then soaked in clean water for an additional 12–24 hours (second fermentation). This double fermentation is believed to contribute to Kenya's characteristic bright acidity and clean flavor clarity.

Flavor Profile

Kenyan coffee is famous for its:

• Blackcurrant / Black cherry: The signature Kenyan note, especially from SL28
• Tomato-like acidity: A savory complexity distinct from fruity Ethiopians
• Citrus and grapefruit: Phosphoric brightness that "pops" on the palate
• Syrupy body: Despite high acidity, quality Kenyan coffees have excellent mouthfeel
• Long, juicy aftertaste

Growing Regions

Nyeri — Considered Kenya's premium origin. High altitude (1,800–2,200m) and rich volcanic soils produce coffees with intense blackcurrant and complex acidity. Estates like Gakuyuini and Tegu are internationally acclaimed.

Kirinyaga — Slopes of Mount Kenya. Fruity and complex, often with red fruit notes.

Murang'a / Thika — Lower altitude, slightly milder profiles than Nyeri.

Embu — Emerging region with well-balanced cups, fruit and chocolate notes.

Brewing Recommendations

Kenya's bright acidity shines in methods that allow clarity:

• Pour-over (V60, Chemex): Best for highlighting the complex fruit notes
• Water temperature: 90–93°C
• Grind size: Medium-fine
• Ratio: 1:15 to 1:16 (1g coffee : 15–16ml water)

Summary

Kenya produces some of the world's most distinctive and prized specialty coffees.

Key takeaways:

• SL28 and SL34 are Kenya's iconic high-altitude varieties, producing blackcurrant and phosphoric acidity
• AA grading indicates bean size, not quality — look for estate name and processing
• Double-fermentation washed processing is unique to Kenya, contributing to exceptional clarity
• Brew at 90–93°C with pour-over for the best expression of Kenya's bright, complex character