What do Kenyan coffee grades AA and PB mean?

Kenya's coffee grading system sorts green coffee bean by size before roasting: E, PB, AA, AB, C, TT, T, and MH/ML. AA carries a screen size of 18, AB a screen size of 16, and E, called Elephant grade, is the largest. PB means peaberry, a single round bean that occurs in roughly 5% of Kenyan coffee.

Grading by size exists to keep roasting consistent, since beans of similar size heat at similar rates. Kenya AA coffee is grown at about 6,600 feet or above. Many drinkers believe peaberries cup better than other grades, though the difference depends on the lot. Weigh the coffee grades against flavor rather than reputation alone when buying.

Kenya AA coffee is often hailed as one of the world's top specialty coffees, but what exactly do the letters AA and PB stand for? This article systematically breaks down Kenya's green coffee bean grading system, including the meaning and specifications of each grade—E, PB, AA, AB, C, TT, T, and MH/ML—and takes a deep dive into the flavor differences between AA and PB peaberry beans. Drawing on years of roasting experience, Front Street Coffee uses an Ichamama Peaberry as an example to share peaberry roasting approaches and cupping performance, while also offering brewing parameter suggestions for Kenya AA, helping coffee lovers fully understand the key points of buying and tasting Kenyan coffee.

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Kenya AA coffee has long enjoyed an extremely high reputation in the global specialty coffee scene and is often listed as one of the world's finest specialty coffees. Many friends new to Kenyan beans often ask Front Street: what exactly does AA mean? The letters PB are equally puzzling. When faced with these terms, do you also feel confused? Today, Front Street will systematically discuss knowledge related to Kenyan coffee.

In fact, both AA and PB are grade names for Kenyan coffee. In addition, Kenyan coffee grades also include:

Kenya E (Elephant Bean)

Kenya PB (Peaberry)

Kenya AA

Kenya AB

Kenya C

Kenya TT

Kenya T

Kenya MH/ML

Before coffee beans enter the roasting stage, the green beans are usually graded. Kenya's approach is to use green bean size as the basis for grading, with the aim of ensuring roasting consistency—because beans of similar size heat at similar rates, while a mix of sizes can easily lead to uneven roasting, such as small beans being over-roasted while large beans are not yet fully roasted.

Kenyan E-grade coffee beans, also called Elephant grade, are the largest type in Kenyan coffee. Kenyan PB is called pea bean or peaberry. Normally, a coffee fruit contains two semicircular beans, but the PB fruit produces only one bean, with a shape closer to round. This occurrence is quite rare, accounting for only about 5% of Kenyan coffee beans. Many people believe that peaberries have better flavor performance than other grades. Kenyan AA coffee beans are grown at an altitude of about 6,600 feet or above, with a screen size of 18.

Kenyan AB has a screen size of 16 and is made by mixing A-grade and B-grade coffee beans. Grade A is screened using a 6.8 mm screen, while Grade B uses a 6.2 mm screen. These two grades, when mixed, make up Kenyan AB grade. Grade C Kenyan coffee beans have a screen size of about 15. Kenyan TT refers to light-density beans separated from AA, AB, and E grades by aspiration. Kenyan T refers to beans that are damaged, defective, and relatively small. Finally, NH and ML refer to immature beans. So what exactly is the difference in taste between Kenyan AA and PB? Front Street will explain this in detail below.

The above is the Kenyan coffee grading system compiled by Front Street. To give everyone a deeper understanding of Kenyan PB coffee beans, Front Street will use a Kenyan PB bean purchased earlier as an example for a detailed introduction. The specific green bean information is as follows:

Kenya Nyeri Ichamama Peaberry

Country: Kenya

Region: Nyeri, Karima Village

Washing Station: Ichamama

Producer: Smallholder farmers who are members of the Othaya Farmers' Cooperative Society

Altitude: 1,700 – 1,750 meters

Variety: SL28 / SL34

Soil: Volcanic soil

Temperature: 18 - 26ºC

Harvest Season: November – January

Processing Method: Water selection, washed, then African-style raised-bed sun drying

Kenya is located in East Africa, adjacent to Ethiopia, the birthplace of coffee. Kenyan coffee producers are broadly divided into two types: large estates and smallholder farmers, but regardless of the type, after processing, the coffee beans are sent to the official coffee board for grading and auction. The coffee board sends samples of the green beans to be auctioned to interested buyers and holds an auction every Tuesday in the capital, Nairobi, namely the NCE bidding session.

This Kenyan peaberry from Front Street comes from the Othaya Farmers' Cooperative Society, located in Othaya town in the Nyeri region of Kenya's central highlands, about 120 kilometers north of the capital Nairobi. It is currently the largest coffee farmers' organization in Kenya. The cooperative is almost entirely organized and managed by smallholder farmers themselves and has obtained Fairtrade certification. Othaya Cooperative's vision is to become Kenya's best-managed cooperative, with the ultimate goal of producing the highest-quality coffee, selling it at the best price, and enabling all member farmers to live the best possible lives.

Othaya Cooperative has 19 washing stations under its management, including Kamoini, Gatugi, Ichamama, and others. The cooperative was founded in 1956 and currently has about 14,000 members, a considerable scale. To improve yield and quality, Othaya applies to the World Bank for grants to hire consultants for agronomy and harvest training; they also have their own nursery and laboratory, continuously developing new coffee varieties (such as Batian) for planting trials. Othaya Cooperative holds its own cultivation technology and marketing licenses, can trade directly with the international market, and is also a member of the Kenya Cooperative Coffee Exporters (KCCE), so it can bypass the NCE bidding session and export coffee directly under the KCCE name.

Ichamama is located in Karuthi, Nyeri, with a total cultivation area of 310 hectares. 927 farmers grow coffee on fertile red volcanic soil, with the Ichamama River right beside it, providing excellent fresh water. In addition to coffee, tea is also grown in this area. The altitude is extremely high, exceeding 1,800 meters. Cool nights allow coffee cherries to mature slowly, ultimately producing a wonderful cup flavor. Why Kenyan coffee is so acidic is also related to its altitude.

Front Street designed a corresponding roasting plan based on the characteristics of this bean. This Kenyan peaberry green bean is emerald green, with relatively high moisture content and also high density. Peaberries tumble relatively smoothly in the drum and heat more evenly than flat beans. However, the bean quality and density of this bean result in poor heat penetration, so Front Street's roasting design needed to allow heat to fully reach the core of the bean, extending the dehydration time so that the coffee would be better homogenized during the roasting preparation stage, then entering first crack with higher heat to showcase its rich berry-like flavors and full body.

Front Street conducted a total of 4 roasting batches and observed the bean condition and aroma changes in each batch. The roaster at Front Street Coffee (FrontStreet Coffee) found that this bean absorbs heat very quickly; using a conventional drop temperature would cause the turning point to be too high, and after first crack, because water vapor carries away a large amount of heat, the ROR would drop sharply (Crash). So, based on the changes in the beans, we adopted 4 different roasting methods—1. FSSF style (fast start, slow finish) roasting; 2. Increasing heat at the yellowing point to promote the Maillard reaction and extend acidity roasting; 3. Increasing heat at the browning point to promote caramelization and increase sweetness roasting; 4. SSFF (slow start, fast finish) gradually increasing heat roasting.

Comparing the state of the roasted beans from the 4 batches, it can be seen that if a stepwise decrease in heat is used, this bean shows more attached silver skin, judged to be underdeveloped, and the aroma released during roasting is mainly a grassy acidity. The other three batches, due to increasing heat, had ideal development, and during roasting one could smell the sweet aromas of dark plum, blackcurrant, and sugarcane. Therefore, roasting profiles No. 2, 3, and 4 were selected for cupping to see which roasting method could better showcase the bean's flavor characteristics.

Through cupping, Front Street concluded that this PB peaberry has a steady, mature aroma with a slight red wine-like acidity. When slurping, one can perceive dark berry flavors, malic acidity, a full and heavy body, along with sugarcane sweetness and a slight cocoa aroma. By comparing the flavors presented by different roasting methods, we found that using a longer dehydration time than usual can remove the astringency caused by uneven dehydration, making the mouthfeel more rounded.

Of course, the above is only Front Street's understanding of the roasting method: using a longer dehydration time than usual to remove moisture from the beans, and increasing heat at the browning point and before first crack to push the crack. Interestingly, by adding heat before first crack to supplement energy, it is possible to effectively prevent this bean's ROR from dropping sharply and from over-development. Kenyan peaberries are beans that Front Street Coffee (FrontStreet Coffee) has had relatively little exposure to, and the roasting of peaberries as well as the flavor of Kenyan peaberries are very much worth exploring in depth. This Ichamama Peaberry gives an overall impression different from ordinary Kenya AA; it does not have very bright acidity or ripe tomato aroma, and its flavor is soft.

Words alone are not enough. In order to directly analyze the difference between the two, Front Street brewed a cup of Kenyan AA coffee beans using the same parameters. As before, first a brief introduction to the coffee bean information:

Kenya Timani Girl AA Coffee Beans

Region: Nyeri Ndima-ini Washing Station

Altitude: 1700-1900 meters

Variety: SL28&SL34

Processing Method: K72 washed

Grade: AA

Although this coffee bean is labeled as 72-hour fermentation, it actually fermented for 80 hours. Therefore, the acidity of this washed Kenyan coffee will be more pronounced. So how should Kenyan coffee be brewed? Front Street brewing suggestions:

Dripper: V60

Water Temperature: 90 degrees

Dose: 15 grams

Coffee-to-Water Ratio: 1:15

Grind Size: Medium-fine (77% passing rate with No. 20 standard sieve)

Front Street Extraction Method: Front Street Coffee (FrontStreet Coffee) uses staged extraction, blooming with 30 grams of water for 30 seconds, then pouring in a small stream in circles until 125 grams for the stage break. When the water level drops and is about to expose the coffee bed, continue pouring until 225 grams and stop pouring. When the water level drops and is about to expose the coffee bed, remove the dripper. (Timing starts at the beginning of blooming.) Extraction time is 2'00".

Kenyan Coffee Characteristic Taste: This coffee has very obvious dark berry flavors, with a charming bright sweet-and-sour sensation on entry. As the temperature drops, it turns into grape-like acidity, and at low temperatures there is a stimulating plum-like acidity. Overall, it has a high level of complexity, is delicate, and has a long finish.

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