The Source of Kenya Beans' Bright Acidity

Fans of fruity acidity probably love Kenyan beans. Unlike the elegant acidity of Yirgacheffe, Kenyan beans boast exceptionally prominent acidity, rounded body, sweetness, and a full mouthfeel. This is thanks to the SL28 and SL34 varieties grown in Kenya.

According to the SL Laboratory (as explained by its botanists, SL28 and SL34 are genetic variants. Among them, SL28 has a mixed lineage of French Mission, Mocha, and Yemeni Typica. The SL series was developed through research and selection based on the ancient Yemeni Mocha variety and the Bourbon variety from Réunion Island. Today, these varieties dominate Kenya’s coffee production. Relatively speaking, SL-28 enjoys higher prestige, while SL-34 yields greater quantities and is grown at slightly lower altitudes.), as explained by its botanists, SL28 and SL34 are genetic variants. Among them, SL28 has a mixed lineage of French Mission, Mocha, and Yemeni Typica.

There’s also Kenya’s unique high-concentration phosphoric acid soil and the double fermentation washed processing method for green beans.

Although Kenya borders Ethiopia, which we’re all familiar with, coffee cultivation in Kenya only began to expand in the early 20th century.

Kenya mainly grows four varieties: SL28, SL34, K7, and Ruiru 11. SL28 is the most flavor-rich variety, but since it’s not very resistant to leaf rust, it can only be grown at mid-to-high altitudes where leaf rust is less severe, resulting in lower yields. SL34 has better moisture tolerance, making it suitable for humid and rainy mid-to-high altitude regions. K7 is a Typica variant with some resistance to leaf rust and coffee berry disease, and its flavor isn’t bad, so it’s grown in low-altitude disease-prone areas. Finally, Ruiru 11 is a Catimor variety with Robusta genes and the poorest flavor.

Kenya’s Coffee Trading System

Kenya’s coffee producers are mainly divided into two types: large estates and so-called “smallholders.” However, whether from large coffee estates or smallholders, the vast majority of their processed coffee beans are sent to the official Kenya Coffee Board for grading and evaluation.

The Coffee Board first sends green bean samples of the collected beans (destined for auction) to interested buyers for cupping. Every Tuesday, auctions are held at the Nairobi Coffee Exchange in Kenya’s capital, Nairobi. Through a transparent auction mechanism and a dual system of official sales agents and independent sales agents, foreign buyers can directly negotiate with producers to purchase coffee without going through the official auction board. This ensures producers receive fairer compensation for their efforts, rather than having most of the profits taken by intermediaries.

The Kenyan government takes the coffee industry extremely seriously. Here, cutting down or destroying coffee trees is illegal, and the country’s coffee quality standards are among the strictest in the world, as evident from its grading system.

Kenya Coffee Grading

Kenya’s coffee grading is primarily based on bean size, shape, and hardness, ranked from highest to lowest as AA or AA+, AB, PB, C, E, TT, T:

AA grade: Bean size between 17–18 mesh

AB grade: Bean size between 15–16 mesh, making up the majority of production and the most common green bean grade

C grade: Bean size between 12–14 mesh

PB grade: Round beans, accounting for about 10% of all coffee beans

E grade (elephant bean): A large mutation bean formed by two beans fused together, also called Elephant Ear, mostly over 18 mesh, also known as elephant bean, and very rare.

TT grade: Lighter-weight beans sifted from AA and AB grades using an air classifier, indicating softer beans that don’t meet hardness standards

T grade: Below 12 mesh. T grade consists of lighter-weight beans sifted from C grades using an air classifier, with softer beans that don’t meet hardness standards, smaller size, and more defects

MH/ML grade: Unwashed beans that haven’t been sorted, consisting of beans that fell off after harvesting, making up about 7% of all coffee beans, and belong to the lowest grade, intended only for Kenya’s domestic market.

The above is Kenya’s official national grading system. In addition, Kenya’s exporters or green bean traders have introduced special grading (not officially recognized by Kenya’s national standards) for AA and AB grade green beans, namely TOP, PLUS (+), and FAQ.

　　TOP 

This grading is based on cupping results and is not yet an official Kenya national standard. Since exporter-added grading inevitably involves commercial considerations, it should only be used as a reference. Ultimately, proper roasting and cupping are the most reliable methods.

　　PLUS（+）

The same bean can yield different results depending on the company—Company A and Company B may have different standards—leading to varying outcomes. After all, without a unified grading standard, there’s no benchmark for cupping results, so this can only serve as a reference. Ultimately, proper cupping is essential.

　　FAQ 

Fair to Average Quality may have some minor defects but doesn’t affect flavor.

Speaking of this, we often see terms like “AA+” and “AA++.” Is there anything particularly special about them?

As mentioned earlier, grades like TOP, PLUS (+), and FAQ are determined by Kenya’s coffee traders. Even for the same bean, each company’s standards differ, leading to varying results. Since these are exporter-added grades, commercial considerations inevitably come into play, so they should only be used as a reference. The actual performance of the beans after roasting and cupping is what truly matters~