Introduction:Kenyan coffee is renowned for its bright acidity and clean, juice-like flavor profile, but do you know the grading logic behind the commonly seen 'AA', 'AB', or even 'AA TOP' in the domestic market? This article delves into the official eight-tier coffee bean grading system of Kenya, explaining the correlation between size, shape, and quality, while focusing on the variety characteristics of the Sidama region, predominantly SL28 and SL34. We also share the cupping notes of a well-known brand’s Kenyan 'Little Tomato' AA-grade washed coffee, along with practical parameters for light roasting and iced pour-over brewing to help you better understand this classic bean variety that’s both sweet and tangy.

Kenyan coffee is globally celebrated for its clean brightness, solid acidity, and vibrant, juicy character. When you see Kenyan beans labeled as 'AA', 'AB', or 'AA TOP' on the market, have you ever wondered what these grades actually mean? In fact, these letters represent an official Kenyan grading system based on physical characteristics such as bean size, shape, and density. Different grades not only reflect appearance but are also closely tied to flavor potential.

The Kenyan coffee grading system is mainly divided into eight categories: AA, AB, PB, E, C, TT, T, and MH/ML. Among them, AA and AB are the two most common grades on the international market. AA-grade coffee beans are sized between 17 and 18 mesh, considered large and high-density beans, generally regarded as having elegant and complex flavors and are representative of high quality. In contrast, AB-grade beans are sized between 16 and 17 mesh. Though their flavor profile is slightly inferior to AA, they offer higher yield and more affordable pricing, making up a significant proportion of the market—about 40% of total exports.

Beyond AA and AB, Kenya has several special grades. For example, PB (Peaberry), commonly known as round beans, refers to the rare occurrence where a coffee cherry develops a single, round seed instead of two flat ones. These beans account for only about 5% of total production and are often considered premium. Grade E refers to elephant beans, which result from two beans fusing during development into a single unusually large bean, sized over 21 mesh. However, due to their rarity and high processing difficulty, they have limited market circulation. Grade C beans are sized between 12 and 14 mesh, significantly smaller in size and usually not considered specialty grade. TT grade consists of lightweight beans screened from E, AA, and AB grades using air separation, while T grade consists of defective beans selected from Grade C—both are generally not regarded as specialty coffee. Lastly, the MH/ML grade often contains underripe or overripe beans and is of lower quality, typically consumed domestically in Kenya and not exported.

It’s worth noting that although bean size is often considered one indicator of quality, it is not absolute. As a result, some exporters or traders may apply a secondary grading system based on cupping scores, with common labels including 'TOP', 'Plus (+)', and 'FAQ'. However, such grading is not part of Kenya’s official standards, varies by vendor, and should only be taken as a reference—the actual flavor still depends on cupping results.

The history of coffee cultivation in Kenya dates back to the British colonial period, when introduced coffee varieties and processing techniques laid the foundation for Kenya’s refined grading and management systems today. Currently, the main varieties grown in Kenya include SL28, SL34, Batian, K7, and Ruiru11, among which SL28 and SL34 are favored in most high-end producing regions for their outstanding acidity and flavor performance.

The Sidama region is located near Kenya’s capital, Nairobi, and is a town surrounded by agricultural areas and natural waterfalls. It is also one of the important coffee-producing areas. With approximately 2,000 coffee farmers, the region's coffee cultivation history dates back to the late 19th century, initially introduced from neighboring Ethiopia. Over time, through localization and improvement, it gradually developed into the current variety structure dominated by SL28 and SL34, accounting for about 90% of local plantings. The altitude in Sidama ranges between 1,550 and 1,750 meters. This high-altitude environment provides ideal growing conditions for coffee, resulting in a flavor profile characterized by bright acidity, rich fruity aromas, and honey-like sweetness.

Taking the Sidama region as an example, a well-known brand’s 'Kenyan Little Tomato' AA-grade washed coffee is produced using the locally common SL28 and SL34 varieties, processed via the K72 washed method to enhance its clean and bright acidity. These beans are plump and full, and to highlight their robust fruit acidity and juice-like mouthfeel, roasters often opt for a light roast. This approach brings out an active acidity reminiscent of freshly squeezed juice, delivering a refreshing and non-cloying taste.

If you’d like to try brewing this uniquely flavored Kenyan Little Tomato AA-grade washed coffee at home, you can refer to the following iced pour-over parameters: use 15 grams of coffee, with 10 times the amount of hot water (150 grams at 92°C) for high concentration and high extraction, paired with 5 times the ice (75 grams). Grind size is recommended to be adjusted to approximately 83% passing through a #20 sieve—for instance, EK43s at setting 9 or C40 at setting 22—using a Hario V60 filter. The brewing process involves a three-stage method: first, place 75 grams of ice in the bottom carafe, then put the coffee grounds into the filter and gently level them. The first stage involves pouring 30 grams of hot water in small streams (3–4 ml per second) in a circular motion from the center outward, followed by a 30-second bloom. The second stage uses the same method to pour 60 grams of water, taking care to control the liquid level to avoid it getting too high, which could lead to under-extraction. Finally, when the coffee is nearly finished dripping, pour the remaining 60 grams of hot water at a rate of 3 ml per second until completed. The entire extraction time should be controlled between 1 minute 50 seconds and 2 minutes.

The resulting iced Kenyan Little Tomato coffee brewed with the above parameters showcases a rich berry character. On the palate, it offers acidity reminiscent of cherry tomatoes, dark plums, and pears—balanced, sweet, and refreshing. The finish lingers with a subtle caramel aroma, which becomes even more vivid with the presence of ice. It’s an excellent choice for summer or for coffee lovers who enjoy fruity, tangy profiles.

The above content is compiled by CoffeeHunters, a coffee news website.