How does the Kenya K72 coffee bean process shape AA flavor?

Kenyan coffee owes its bright fruit acidity and heavy body to the K72 double washing method, a fermentation process that runs at least 36 hours. Cherries are pulped in the evening after selective coffee picking, fermented overnight in an upper tank, washed once, then moved to a lower clean-water tank where circulating water is changed every 3 to 5 hours before a final 12-hour soak and drying.

Kenya grades coffee by bean size across nine levels, with PB peaberry making up about 10 percent of production, and AA representing the largest screen size. The SL28 and SL34 varieties, selected decades ago, carry the blackcurrant and citrus notes that manual pour-over brewing draws out of these dense, high-grown AA beans.

Kenyan coffee is renowned worldwide for its bright fruit acidity and rich body, and the core of this unique flavor is the double washing fermentation process known as K72. This article will provide a complete analysis of the Kenyan double washing method's procedural details, outline the nine-level grading system based on bean size, introduce the origins of the two legendary varieties SL28 and SL34, and present the flavor layers revealed by Kenyan AA coffee beans under manual brewing. Whether you want to gain an in-depth understanding of origin processing methods or are looking for a daily staple bean with bright fruit acidity and solid sweetness, Front Street Coffee's Kenyan AA is a choice worth noting.

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Kenya “double washing method”

Kenya's double washing method is also called Kenyan double fermentation.

The reason is that its washing tank has two levels, upper and lower. Generally, in the evening, coffee farmers first sort out defective beans from the harvested coffee cherries, remove the pulp, and then pour the parchment beans with mucilage into the upper fermentation tank, or use dry fermentation without soaking in water. After fermenting overnight, they wash it once with water the next morning to remove most of the pectin, then move it to the lower clean water tank for a second fermentation.

During the second fermentation, the circulating water is changed every 3~5 hours to prevent mold growth and foul odors, and then it is directed into washing channels to remove the remaining pectin.

(The picture shows the cleaning and collection step by coffee farm workers after the second washing)

The entire process above takes at least 36 hours. After that, the thoroughly rinsed parchment beans still need to be placed in a clean water tank and soaked for at least 12 hours. Finally, they are dried and dehydrated before the process is considered complete. This total time is several times longer than the total processing time in Central and South America, and the water demand is also considerably higher.

Kenyan coffee grade classification

Kenya is a well-known origin that grades coffee by bean size. It is usually divided into nine grades. According to bean type, there is PB (peaberry, about 10% of total production). In addition, according to size, there are also E (elephant bean), AA, AB, C, T, TT, MH, and ML. The best coffee grade is peaberry PB, followed by AA++, AA+, AA, AB, and so on in order.

1) Common classifications:

Hand-picked coffee cherries are manually sorted to remove defects such as unripe and overripe cherries, then pulped, fermented for about 36 hours, sun-dried on metal mesh racks, and finally hulled at the processing plant to become the charming Kenyan green beans with a blue-green appearance.

These beautiful green beans are graded according to size, shape, and weight:

E: kenyaE, elephant bean, 18 mesh and above (including peaberry)

AA: KenyaAA, 17-18 mesh,

AB: KenyaAB, 15-16 mesh, a mix of grade A and grade B

TT: light beans screened out from AA and AB by an airflow separator

PB: KenyaPB, 15 mesh and above, peaberry

C: 12-14 mesh, as well as light beans screened out from PB by an airflow separator

T: below 12 mesh, with more defective beans, broken beans, and light beans

HE: beans outside the above grades become HE (HulledEars)

2) Green beans that have not undergone official standard grading are UG (ungrade)

E, AA, AB, PB→UG1

C, TT, T, HE→UG2

(Note: 17 mesh (6.8mm) and above is grade A, 16 mesh (6.3mm) and above is grade B. 18 mesh = 18/64 inch, 1 inch = 25.4 mm) Kenyan coffee varieties

The first variety brought to Kenya for planting was Bourbon. In the 1950s, the agricultural research institution ScottLaboratory, through unremitting efforts, bred two excellent hybrid varieties, SL-28 and SL-34, overturning the long-held prejudice that artificially selected varieties could not be superior to natural varieties. SL-28 and SL-34 helped Kenyan coffee form its unique flavor characteristics and established a perfect reputation in the coffee world.

According to botanists at the SL laboratory, SL28 and SL34 are genetic variants. Among them, SL28 has a mixed lineage of French Mission, Mocha, and Yemen Typica. The original goal of cultivating SL28 was to mass-produce coffee beans that combined high quality with resistance to pests and diseases.

Although SL28's yield later did not reach the expected high volume, its bronze leaf color and broad-bean-shaped beans have excellent sweetness, balance, and complex, varied flavors, as well as notable citrus and smoked plum characteristics. SL34 is similar in flavor to SL28. In addition to complex and varied acidity and a excellent sweet finish, its body is heavier, richer, and cleaner than SL28. SL34 has a lineage of French Mission, Bourbon, and more Typica. Its bean appearance is similar to SL28, but it is better able to adapt to sudden heavy rain. It is these two important varieties that lead us to understand the unique Kenyan style: intense and rich fruit acidity, a full body, and a beautiful balance.

Kenyan coffee growing regions

Kenya's coffee-producing areas are mainly concentrated in the highland regions represented by Mt. Kenya. The tropical climate and acidic red volcanic soil provide a naturally suitable growing environment for coffee. The seven major production areas are the most famous, including Nyeri, Thika, Kiambu, Kirinyaga, Ruiru, Murang'a, and the western side of Mount Kenya. Major production areas include Nyeri and Ruiru in the central region.

Kenyan coffee processing

Large farms usually have independent processing facilities. The many smallholder farmers usually hand-pick ripe coffee cherries themselves. Coffee picking is labor-intensive work, and during the harvest season the whole family may need to turn out and even hire workers. The harvested fresh coffee cherries need to be transported promptly to cooperative-owned coffee processing factories for pulping, and the means of transport may be ox carts, pickup trucks, or trucks. After pulping, the parchment coffee is briefly kept at the cooperative's processing plant and then sent to privately owned factories for hulling.

Front Street Coffee's Kenyan AA coffee beans are carefully selected from Kenya's central production region and use K72 washing processing. The beans are plump and uniform in shape. After brewing, they present bright citrus and smoked plum acidity, with a tomato-like fresh sweetness in the middle, a clean and lingering finish, and solid sweetness.

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