Why Are Kenya AA Coffee Beans the Largest Coffee Bean Grade?

Kenyan green coffee is graded mainly by bean size, color, shape, and density, and local traders treat bean size as the leading quality signal. The largest and most uniform beans are classed AA, which is why Kenya AA coffee beans from the Thika region are prized for plump shape and bright acidity, with varieties SL28 and SL34 behind the cup.

Thika sits near Nairobi and counts roughly two thousand growers, with about ninety percent of plantings in SL34 and SL28. The K72 Kenyan-style double fermentation washed process, 1,550 to 1,750 meters of altitude, and a V60 pour-over at 92°C, 1:15 ratio, and three pours bring out black plum, smoked plum, and a black tea finish.

Kenya AA coffee beans, with their plump beans and bright acidity, have long been a favored African representative in the specialty coffee world. Starting from Front Street Kenya Asali coffee beans, this article systematically reviews the growing background of the Thika region, the K72 Kenyan-style double fermentation washed process, and the flavor performance of the two main varieties SL28 and SL34. It also shares in detail Front Street's brewing approach for light-roast Kenya AA, including V60 dripper selection, 92°C water temperature, 1:15 coffee-to-water ratio, and a three-pour pouring technique, helping coffee lovers recreate at home the classic Kenyan flavor interwoven with black plum, smoked plum, and black tea finish.

Front Street Coffee: Front Street Kenya Asali Coffee Beans

Region: Kenya Thika

Washing Station: Asali Honey Washing Station Altitude: 1550-1750 meters Grade: AA TOP Variety: SL28, SL34 Process: Kenyan 72-hour washed

The grading system for Kenyan green coffee beans is mainly determined by bean size, color, shape, and density. In the view of local industry practitioners, bean size is the primary indicator of quality—the larger the beans and the more uniform their shape, the more ideal the generation and accumulation of aromatic compounds during roasting. For this reason, the largest and highest-quality Kenyan beans are classified as AA grade. This Kenyan coffee launched by Front Street Coffee is selected from the highest AA grade and carries Kenya's signature fruity acidity.

The Thika region is located around Kenya's capital, Nairobi. Quite a few coffee fields are scattered across the outskirts of Nairobi. Thika itself is an industrial town, but it is surrounded by farmland and waterfalls. The area has roughly two thousand coffee growers. Thika's coffee-growing history can be traced back to the late nineteenth century, when seeds were introduced from Ethiopia to the north. Since then, through continuous local selection and improvement, the commonly cultivated varieties now include four types: Bourbon, Kents (SL34, SL28), Typica, and Riuri 11. At present, about ninety percent of the planted varieties are SL34 and SL28. Batian, a new variety released only in 2007, has still not been widely promoted. The coffee flavor of the Thika region is known for bright fruity acidity, a thick berry-juice body, and honey-like sweetness.

The biggest difference between Kenyan-style washing and that of Central and South America lies in its use of double fermentation, commonly known as K72 washing. This method repeats the steps of fermentation and rinsing in cycles: after harvesting, the coffee cherries are first sorted, the finest cherries are selected and depulped, then they enter the fermentation stage, which lasts 24 hours, after which they are rinsed clean with clean water.

Immediately afterward, they are fermented again with clean water for 24 hours and rinsed, and this cycle is repeated three times in total, for a total duration of 72 hours. This is the Kenyan-style 72-hour fermentation washed method, abbreviated as [K72]. Front Street Coffee's experience is that K72 washing, compared with conventional washing, can further elevate the acidity and cleanliness of the coffee beans.

SL28 and SL34 Varieties

The main varieties of Kenyan coffee include SL28, SL34, K7, Ruiru11, and Batian, among which SL28 and SL34 contribute 90% of Kenya's total production of high-quality coffee beans. SL is taken from the abbreviation of the Scott Laboratories in Kenya. In the 1930s, Kenyan coffee trees were widely infected with coffee berry disease, and Scott Laboratories was commissioned by the government to begin breeding disease-resistant new varieties. Among the research results, No. 28 and No. 34 showed strong disease resistance and exceptionally outstanding flavor, so they were promoted to farmers for widespread planting. The SL series belongs to the Bourbon lineage in the coffee tree family and displays excellent acidity in the Kenyan producing region. Through cupping, Front Street found that SL28 and SL34 have excellent sweetness, balance, and multi-layered, changeable flavors, with particularly distinct characteristics of citrus and smoked plum.

Brewing Flavor of Front Street Kenya AA Coffee Beans

This Kenyan coffee obtained by Front Street carries flavors of black berries and stone fruits. In order to retain the fruity aroma as much as possible, Front Street's roaster chose a light roast. Through cupping comparison, its dry aroma presents notes of cherry tomato, smoked plum, and caramel; on the palate, it has dark stone fruit tonality, such as plum, plum, and apricot, with full-bodied acidity. Therefore, in the brewing stage, Front Street also focuses on preserving more of the fruity charm of Front Street Kenya AA.

Light roasting allows high-altitude coffee beans to retain more floral and fruity aromas. Compared with medium-dark roasting, lightly roasted beans have a denser internal structure and require a higher water temperature and finer grinding to fully release flavor compounds. Front Street here uses hot water at 92-93°C for extraction, with grind size controlled so that 80% passes through a No. 20 standard sieve.

Front Street's flavor descriptions for every coffee are based on freshly roasted beans. If coffee beans are stored for more than one month, part of the aroma has often already dissipated, making it difficult to reproduce the original performance during brewing. Front Street deeply understands the importance of freshness, so it only ships coffee beans within 5 days after roasting, ensuring that when you receive them they are still within the full peak-flavor period.

In terms of dripper selection, Front Street Coffee baristas are accustomed to using a resin V60 dripper to extract medium-light roasted coffee beans. The V60 body has ribs connecting the top and bottom and a large central round hole, which can speed up the flow of water downward; the spiral vent groove design extends the water flow path, increasing the contact time between coffee grounds and hot water. Each stream of water follows the grooves and converges toward the center of the dripper, so the coffee grounds bear more concentrated pressure, and the extracted coffee has a richer layering.

The pour-over parameters are as follows:

Dripper: V60

Water temperature: 92°C

Coffee dose: 15g

Coffee-to-water ratio: 1:15

Grind size: fine granulated sugar size (sift through a No. 20 sieve to 80%)

Three-pour extraction: First pour 15 grams of coffee grounds into the dripper and tare the scale to zero. For the first pour, add 30g of water and bloom for 30 seconds, starting the timer at the same time. Use a slow stream throughout, circling from the center outward, making sure to wet the entire coffee bed. For the second pour, switch to a slightly larger stream and add 120g of water, with the aim of lifting the entire coffee bed. The water column should be poured vertically and evenly. At this point the timer scale shows 150g, and the pour is completed in about 55 seconds. When the liquid level drops to the halfway point, begin the third pour using a thin stream in a small circle, adding 90 grams, trying to control the stream so it does not circle too widely, otherwise it is easy to disturb the coffee bed and cause under-extraction. The final total water amount is 240 grams, and the drip completion time is about 2 minutes 10 seconds. After removing the dripper, swirl the coffee liquid in the server to mix it evenly and it is ready to taste.

This Front Street Kenya Asali coffee enters with the acidity of dark fruits such as black plum and smoked plum, presents a full-bodied sweet-and-sour taste of apricot and stone fruits in the medium-temperature range, and finishes with a rounded black tea note.

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