Kenyan Coffee: Variety, Washed Processing, and Bright Structure

Kenyan coffee is among the most recognisable in the world, and the reasons are unusually well documented: specific varieties, a rigorous processing protocol, and a grading system that actually means something.

SL28 and SL34

Kenya's signature profile traces substantially to two varieties selected at Scott Agricultural Laboratories in the 1930s.

SL28 is the celebrated one — drought-tolerant, low-yielding, and producing the intense blackcurrant and citrus acidity Kenya is known for.

SL34 is similar in cup with slightly different agronomy.

Both are old, disease-susceptible and expensive to farm, which is why they are gradually being displaced by Ruiru 11 and Batian — disease-resistant and higher-yielding, but generally considered less distinctive in the cup. That tension between agronomic sense and cup quality is an ongoing story in Kenyan coffee.

The double fermentation protocol

Kenya's washed processing is distinctively thorough. A common approach ferments the coffee, washes it, ferments again, then soaks the parchment in clean water — often for 12 to 24 hours — before drying.

That extended soak is unusual and is widely credited with the clarity and pronounced acidity of Kenyan coffee. It is labour-intensive and water-intensive, and it is a genuine processing signature rather than marketing.

Grading, and what AA actually means

Kenyan coffee is graded by screen size: AA is the largest, then AB, PB (peaberry), C and below.

AA indicates bean size, not quality. Larger beans often correlate with good growing conditions, so the correlation is not meaningless — but a well-farmed AB can outcup a mediocre AA, and paying purely for the letters is a mistake.

Look instead at the factory (washing station) name and the cooperative.

What it tastes like

Blackcurrant is the descriptor that recurs, alongside grapefruit, tomato, and an acidity that is high, structured and often described as savoury or winey. Body is medium and the finish is long.

It is a polarising profile. People who love Kenyan coffee love it specifically; people who find it too sharp are not wrong about the acidity.

Buying and brewing

Look for a factory or cooperative name, a stated grade, and a light to medium roast — dark roasting flattens the acidity that is the whole point.

Brew slightly coarser and cooler than you might otherwise, since Kenya's acidity can tip into sharpness when over-extracted.