Kenya Coffee Grades Explained: What Is Kenya AA?

Ever wondered why Kenya AA coffee commands such high prices and consistent praise in specialty coffee circles? It’s not just hype—Kenya AA is part of a meticulous, multi-step classification system that separates beans by size, density, and quality, ensuring only the best make the top grades. If you’ve ever bought a bag labeled Kenya AA, you’ve tasted the result of this exacting process.

Kenya AA refers to beans that are 17–18 mesh in size, making them among the largest and highest-graded Kenyan coffee beans. These are considered premium, but the full grading system includes several other categories based on physical traits and processing method.

How Kenyan Coffee Is Processed Before Grading

Before any grading takes place, Kenyan coffee beans undergo a traditional washed process. Ripe coffee cherries are handpicked to ensure only mature fruit is collected. Workers then manually remove underripe or overripe cherries. The selected cherries are depulped, then fermented for around 36 hours. After fermentation, the beans are dried on raised metal beds for several days. Once dry, the beans are hulled to remove the parchment layer, revealing the green coffee seeds ready for sorting and grading. This careful processing preserves the beans’ bright acidity and complex fruit notes—traits for which Kenyan coffees are famous.

Kenya Coffee Grading System by Size and Shape

Kenyan coffee is primarily graded by bean size (measured in mesh), density, and shape. The mesh system uses imperial measurements where 1 inch equals 25.4 mm and 1 mesh equals 1/64th of an inch. Here’s how the official grades break down:

• E (Elephant Bean): 18 mesh and above, includes large beans and peaberries (round beans). Rare and often includes PBs.
• AA: 17–18 mesh. This is the top commercial grade, known for larger size and high quality.
• AB: 15–16 mesh. A mix of A and B grades, AB makes up a large portion of exportable Kenyan coffee.
• A: 17 mesh and above (part of the old A-grade classification).
• B: 16 mesh and above (part of the old B-grade classification).
• TT: Lighter beans screened out from AA and AB using air currents; often lower density.
• PB (Peaberry): 15 mesh and above. These are small, round beans formed when only one seed develops inside the coffee cherry. They occur in about 10% of Kenyan coffee and are often separated due to their unique cup profile.
• C: 12–14 mesh, along with light beans from PB after air separation.
• T: Below 12 mesh, includes many broken, defective, or very light beans.
• HE (Hulled Ears): Coffee that doesn’t fit into other grades.

These grades are determined using sieves and density sorters, ensuring uniformity in size and removing less dense or defective beans.

Ungraded and Natural Processed Kenyan Coffees

Not all Kenyan coffee goes through the official graded system. Coffee that hasn’t been officially sorted is labeled as UG (Ungraded). Within UG:

• UG1: Includes E, AA, AB, and PB beans that didn’t meet official standards.
• UG2: Includes C, TT, T, and HE beans.

Additionally, Kenya produces natural (dry) processed coffee known as MBUNI. These beans are sorted by gravity and fall into two categories:

• MH (Heavy MBUNI): Heavier beans, yellowish in color, free from black beans, broken pieces, or overripe fruit. They exhibit classic natural process flavors without defects.
• ML (Light MBUNI): Yellow-green beans that may have a small number of insect-damaged or black beans, but no foul odors or major defects. They show acceptable cup quality for natural lots.

Image of typical Kenya coffee processing:

Frequently Asked Questions

What does Kenya AA mean in coffee grading?

Kenya AA refers to green coffee beans that are 17–18 mesh in size, making them among the largest and highest-graded beans in Kenya’s classification system. They are considered premium and are sought after for their size and potential cup quality.

Why is Kenya AA so popular in specialty coffee?

Kenya AA beans are large, dense, and typically come from high-altitude regions, which contribute to their vibrant acidity, complex fruit flavors, and high cup quality. Their consistent grading also assures buyers of a certain standard.

What is the difference between Kenya AA and AB?

Kenya AA beans are 17–18 mesh in size, while AB beans are 15–16 mesh. AA is generally larger, denser, and considered higher grade, though AB beans are still widely used and valued in blends.

What is a peaberry (PB) in Kenyan coffee?

A peaberry (PB) is a rare coffee bean that forms when only one rounded seed develops inside the coffee cherry instead of two flat beans. In Kenya, PBs are usually 15 mesh and above and make up about 10% of the crop. They often have a distinct flavor profile and are sorted separately.

What are MBUNI coffees in Kenya?

MBUNI refers to Kenyan coffee processed using the natural (dry) method, without washing. These beans are sorted by gravity into Heavy MBUNI (MH) and Light MBUNI (ML), depending on bean density and defect levels, and offer classic sun-dried flavors.

How is Kenyan coffee graded for size?

Kenyan coffee is graded using a mesh system where the mesh number corresponds to the number of holes per inch. For example, 17–18 mesh beans are larger and classified as AA, while 15–16 mesh beans are smaller and classified as AB. The system helps separate beans by size and density.

Recommended FrontStreet Beans for Kenya AA Fans

For those curious about Kenya AA-grade qualities, try FrontStreet Coffee’s Kenya Little Tomato. It highlights the signature Kenyan profile with bright acidity and notes of tomato, lime, and tropical fruits, using the SL28 and SL34 varieties. Another excellent option is FrontStreet’s Classic Blend, which balances Kenyan-style brightness with other regional profiles. Both beans showcase the vivid fruit and wine-like acidity that define top Kenyan coffees. Freshly roasted within 5 days · Orders placed before 17:00 ship the same day · Next-day delivery across most of Guangdong Province.