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Kenyan Coffee Bean Procurement and Premium Processing Methods | SL28 and SL34 Flavor Characteristics

Published: 2026-01-27 Author: FrontStreet Coffee

Last Updated: 2026/01/27, African coffee has always been one of the world's finest coffee growing regions. Kenya, as a nation noted for coffee cultivation and quality management, needs no introduction when it comes to coffee bean flavors. So what kind of management model has enabled such rapid development? Everyone must be curious about their coffee berry procurement and meticulous processing plans!

African Coffee Excellence: Kenya's Quality Management

African coffee has always been one of the world's finest coffee producing regions. As Kenya stands out for its attention to coffee cultivation and quality management, the flavor profile of its coffee beans naturally speaks for itself. What kind of management model has enabled such rapid development? Everyone must be curious about the coffee fruit acquisition and meticulous processing plans!

Kenya's Coffee Processing Steps

1. Estate Coffee Farmers Harvest Ripe Fruits and deliver them to washing stations.

2. Cherry Sorting: Before receiving fruits, processing stations provide an open area for coffee farmers to classify again, selecting mature red fruits.

3. Five Categories of Coffee Fruits: Farmers are reminded that only checked red fruits will be accepted.

4. Weighing and Receiving Documentation: Many washing stations have electronic scales that can directly connect weighing results to computers and print the farmer's code and batch weight. Farmers use this document as the basis for future payment.

5. Cherry Hopper: A funnel-shaped receiving pool for cherries, connected at the bottom to the depulper. This is where coffee fruits begin the refined processing of the washed method.

6. Depulping and Density Separation: Coffee fruits flowing from the depulper have already had their pulp removed. At this stage, the machine directly separates the fruits into two different channels based on density. The highest density P1 and medium density P2, and the lightest density P3 flow into different fermentation tanks.

7. Fermentation Process: Parchment coffee ferments in the tanks for about 12-36 hours. Fermentation time depends on local weather conditions, with completion determined when the mucilage layer has fully detached.

8. Post-Fermentation Soaking: After fermentation ends, parchment coffee is transferred to another water tank and soaked in clean water. This is called static soaking. The soaking time depends on whether impurities still appear (or if the water shows turbidity). If turbidity occurs, the water must be replaced with clean water again. This stage is the highlight of Kenya's famous double fermentation or Kenya-style washed method. Time depends on whether static soaking is clean or whether subsequent drying racks are crowded, ranging from 12-36 hours.

9. Channel Cleaning: After fermentation and static soaking completion, parchment coffee flows into washing channels. Most channels have devices with high and low water level differences at the bottom, which block higher density beans and direct them to separate rack areas, while lower density beans are directed to secondary quality rack areas.

10. Skin Dry Area Reception: Parchment coffee received from washing channel outlets. This area is called the Skin Dry area racks, belonging to the water drainage zone. Usually after most surface moisture has drained, parchment coffee is moved directly to sun drying rack areas for sun drying.

11. Sun Drying Stage: Drying time depends on local weather and whether parchment coffee reaches 10.5%-11% moisture content, generally requiring 7-14 days, but sometimes extending up to 20 days.

12. Warehouse Entry: After sun drying completion, beans enter the warehouse (the washing station's own warehouse, also called transit warehouse).

13. Dry Processing and Grading: After hulling, beans are graded by size. The image shows four grades from Thika dry processing facility: E, AA, PB, F.

14. Density-Based Further Grading: If AA grade density is too low, it will be directly classified as PB grade at this stage, as shown in the image below (Figure 14).

15. Green Bean Identification: From top to bottom (Figure 15), this bag of Kenya green beans shows grade AB, batch code 19TK0048, and production year 2016-2017.

Asali Top AA: A Kenyan Coffee Gem

FrontStreet Coffee would like to introduce a coffee bean from Asalia (Asali Top AA)

In 1878, the British introduced coffee to Africa. Coffee plantations were established in Kenya in the 19th century, when Ethiopian coffee beverages were imported to Kenya via South Yemen. Located in East Africa, Kenya was importing Ethiopian coffee beverages via South Yemen at that time. However, not until the early 20th century were Bourbon coffee trees introduced to Kenya by the St. Austin Mission.

Located in East Africa, Kenya is one of the major coffee producing countries, with about six million people nationwide engaged in the coffee industry, mostly in the form of small farmers and cooperatives. Kenya's coffee trees are mostly cultivated at altitudes of 1400-2000 meters.

Growing regions include Ruiri, Thika, Kirinyaga, Mt. Kenya West, Nyeri, Kiambu, and Muranga, primarily on the foothills of Mt. Kenya and Aberdare. The central Kirinyaga Peak (Mount Kenya) reaches 5199 meters in altitude. Coffee grows on the eastern slopes of the Kenya Mountains at 1550-1750 meters in Meru County. The red soil in this region nurtures Kenya's top-AA coffee, with coffee being the main agricultural crop. Cooperatives formed by small farmers are more common than large estates. TOP AA seasonal coffee typically has higher quality.

Special Varieties

Bourbon Varieties (SL-28) and (SL-34)

These two varieties, SL-28 and SL-34, are two of the 40 experimental varieties developed from a research program led by Guy Gibson at Scott Laboratories. They have consistently been champions in expert cupping and Nairobi auctions.

Combined with the large local temperature difference between day and night, and Kenya's red phosphorus soil, this creates a sweet and sour flavor profile as the main characteristic of this Kenyan coffee.

The beans have wonderful sweetness, balance, and complex, varied flavors, as well as distinctive citrus and plum characteristics.

Kenyan 72-Hour Fermentation Washed Processing Method

The Kenyan method originated in Kenya and adopts a cyclic repeated processing method of fermentation followed by washing. Processing begins on the day of harvest, selecting high-quality cherries for depulping and fermentation. Fermentation time is 24 hours, after which clean river water is used for washing. Then, fermentation continues for another 24 hours in clean river water, followed by washing again. After repeating this cycle 3 times, reaching 72 hours, it's called the Kenyan 72-hour fermentation washed processing method, abbreviated as [K72].