What is the difference between Kenya AA and AB coffee grades?

In the Kenyan coffee grading system, the letters AA and AB are not indicators of quality in the sense of 'better' or 'worse,' but rather a classification of physical size. This system is unique to Kenya and is deeply ingrained in the country's coffee trade. The grading process involves passing the beans through a series of screens to sort them by size, which is then used to determine the market value of the lot.

AA beans are the largest, typically measuring 7.2mm or larger. Because they are the biggest, they are often perceived as having the most concentrated flavor and the most uniform roast potential. This perception has led to AA being the most sought-after grade, often commanding a premium price at auction. However, it is important to understand that size does not always equate to superior flavor. A smaller bean can be just as delicious, complex, and vibrant as a larger one.

AB beans are a combination of A and B screen sizes, typically measuring between 6.0mm and 6.4mm. While they are smaller than AA, they are still considered high-quality specialty coffee. In fact, many roasters prefer AB beans because they can sometimes offer a better value-to-quality ratio. The flavor profile of Kenyan coffee—known for its bright, wine-like acidity and intense fruit notes—is present in both grades, as these characteristics are determined by the variety, terroir, and processing, not just the size of the bean.

It is also worth noting that the Kenyan grading system includes other categories, such as E (Elephant beans, which are very large) and PB (Peaberry, where only one seed develops in the cherry). Each of these grades has its own unique characteristics and market demand. The focus on size is a legacy of the colonial-era auction system, which prioritized uniformity to make it easier for large-scale buyers to purchase consistent lots.

In practice, when you are choosing between Kenya AA and AB, you are mostly choosing based on your preference for bean size and price. Both grades can provide an incredible, classic Kenyan coffee experience. If you are looking for the most iconic, large-bean Kenyan coffee, AA is the way to go. If you are looking for a fantastic cup that might offer a bit more value, don't hesitate to try the AB grade. Both are excellent representations of one of the world's most celebrated coffee origins.