Kenya Coffee Bean Varieties SL28, SL34 Grading System AA, AB, PB Grade Flavor Differences

Coffee growing regions are primarily located between the Tropic of Cancer and Tropic of Capricorn. FrontStreet Coffee joins everyone in broadly organizing the characteristics of world coffee distribution. Internationally, coffee is mainly grown in Africa, Central America, and Asia. Among these, Asian coffees generally feature herbal and spicy flavors, American coffees are known for nutty and balanced flavors, while African coffees typically feature fruity acidity.

Africa has always been one of the world's finest coffee-producing regions, known globally for captivating acidity and aroma. Kenya certainly doesn't disappoint. Located in East Africa, right on the equator, with the Indian Ocean to the east, Ethiopia to the north, and Tanzania to the south, Kenya is a major coffee power in East Africa and one of the most important and irreplaceable producing countries. FrontStreet Coffee believes that a coffee bean's flavor has an indispensable relationship with its growing region, altitude, climate, processing method, and variety. Today, FrontStreet Coffee will provide a detailed explanation of Kenyan coffee.

Introduction to Kenyan Coffee Producing Country

The full name of Kenya is the Republic of Kenya, located in eastern Africa, with the equator crossing through the middle and the East African Rift Valley running north to south. It borders Somalia to the east, Tanzania to the south, Uganda to the west, and Ethiopia and Sudan to the north, with the Indian Ocean to the southeast. The country is mostly plateau, with an average altitude of 1500 meters. Mount Kirinyaga (Mount Kenya) in central Kenya reaches 5199 meters, with snow on its summit, making it the second highest peak in Africa.

Altitude, Latitude, and Geology

The equator runs through Kenya, with the country conveniently located within 10 degrees north and south latitude. It belongs to the tropical growing region, with two rainy seasons annually, allowing for two harvests: 60% concentrated from October to December, and the remaining 40% from June to August. Coffee is mainly grown in volcanic soil at altitudes of 1600-2100 meters around the capital Nairobi to the Kenya mountain region. This altitude is suitable for coffee flavor development because the mountainous areas have lower temperatures, slower growth, allowing coffee beans' aromatic components to fully develop, resulting in more prominent fruit acidity and harder texture. This fertile, crescent-shaped coffee specialty zone is the main source of Kenyan specialty beans.

Coffee is Kenya's second export trade product after tea. The main coffee variety grown in Kenya is Arabica, considered one of the highest quality coffee varieties in the world. African coffee growing regions are known for captivating acidity and aroma globally, and Kenya certainly doesn't disappoint. Located in East Africa, right on the equator, with the Indian Ocean to the east, Ethiopia to the north, and Tanzania to the south, Kenya is a major coffee power in East Africa and one of the most important and irreplaceable producing countries.

Kenya belongs to the tropical growing region, with two rainy seasons annually, allowing for two harvests: 60% concentrated from October to December, and the remaining 40% from June to August. Coffee is mainly grown in volcanic soil at altitudes of 1600-2100 meters around the capital Nairobi to the Kenya mountain region. This altitude is suitable for coffee flavor development because the mountainous areas have lower temperatures, slower growth, allowing coffee beans' aromatic components to fully develop, resulting in more prominent fruit acidity and harder texture. This fertile, crescent-shaped coffee specialty zone is the main source of Kenyan specialty beans.

History of Kenyan Coffee

In 1878, the British brought coffee to Africa, establishing coffee plantations in Kenya in the 19th century. At that time, Ethiopian coffee beverages were imported to Kenya via South Yemen. However, it wasn't until the early 20th century that Bourbon coffee trees were introduced to Kenya by the St. Austin Mission. After Kenya's independence in 1964, the coffee industry continued to develop on its existing foundation. Today, it has become a world-renowned high-quality coffee-producing country. Notably, they established an auction system that successfully摆脱 the exploitation of small farmers by other coffee-producing countries (this is where so-called "fair trade coffee" originated).

Kenyan Coffee Varieties

In Kenya, common varieties include SL28, SL34, French Mission Bourbon, and Ruiru 11.

Origin of SL28 Variety

According to literature, in 1931, officials from Scott Laboratories conducted field surveys in Tanganyika (now Tanzania). He noticed that a coffee tree variety in the Moduli region seemed to have resistance to drought, diseases, and pests, so he collected seeds and brought them back to Scott Laboratories. In 1935, the laboratory selected a single tree from the Tanganyika drought-resistant population and continuously improved it through breeding, ultimately launching the SL28, a descendant of the Moduli region. Recent genetic studies have confirmed that SL28 belongs to the Bourbon genetic group.

Characteristics of SL28 Variety

The SL28 variety is easy to grow without special care, with large beans and high yields. It has very high flavor quality. After being released by Kenyan authorities in the 1930s, it was first planted in Kenya and then spread to Uganda. Currently, it has gained wide attention even in Central America. This variety is suitable for medium to high altitude areas and has drought resistance, but remains susceptible to major coffee diseases.

Coffee Flavor of SL28 Variety

The flavor of SL28 variety indeed carries the bright notes of original Bourbon, even the rich acidity of original Mocha varieties, with more complex flavors and rich texture. Although the yield of SL28 was not as high as expected later, its copper-colored leaves and broad bean-shaped beans have wonderful sweetness, balance, and complex, varied flavors, as well as significant citrus and black plum characteristics. It has strong, rich fruit acidity, rich mouthfeel, and beautiful balance. Most particularly, only when planted in Kenya can SL28 have such distinctive character; SL28 planted in other countries only has similar flavors.

FrontStreet Coffee: Kenya Asali Coffee

Region: Thika, Kenya
Processing Station: Asali Honey Processing Station
Altitude: 1550-1750 meters
Grade: AA TOP
Variety: SL28, SL34
Processing Method: Kenya 72-hour washed

Roasting Suggestions

This bean has a full, round body. To fully express its bright, rich acidity, use light roasting.

Machine: Yangjia 800N, 550g green beans input
Entry Temperature: 200°C
First Crack: 5'30", 154.3°C
Development after First Crack: 2'10", discharged at 191.6°C

Brewing Suggestions

Dripper: Hario V60
Water Temperature: 90°C
Dose: 15 grams
Ratio: 1:15
Grind Size: Medium-fine grind (EK43s setting 10)

Brewing Method

Segmented Extraction
Use 30g of water for bloom for 30 seconds. When pouring to 125g with small water flow in circular motion, segment the extraction. When the water level drops and is about to expose the coffee bed, continue pouring to 225g and stop pouring. When the water level drops and is about to expose the coffee bed, remove the dripper. (Timing starts from bloom) Extraction time is 2 minutes.

FrontStreet Coffee Kenya Coffee Flavor Description

The wet aroma has ripe tomato and floral notes. The entry brings cherry tomato and black plum flavors, with bright acidity, clean and most solid, rich mouthfeel, like the weight of an African elephant! The mid-section has prominent sweetness with juicy mouthfeel. The aftertaste has berry aroma and brown sugar sweetness, with green tea fragrance.

SL34 Variety

FrontStreet Coffee learned from reviewing materials that SL34 is a variety selected in the 1930s at Scott Agricultural Laboratories in Kenya. Kenya's Scott Laboratories selected from individual coffee trees between 1935-1939, naming them "SL" varieties. SL34 was selected from a single coffee tree at Loresho Estate in the Kabete region of Kenya. This coffee tree was marked as "French Mission."

French missionaries from the Spiritans order established missionary areas in the Bura area of Kenya's Taita Hills, introducing Bourbon coffee seeds from La Réunion island for cultivation. In 1899, coffee seedlings were brought from Bura village to other French missionary areas in Saint Austin for cultivation. These coffee seeds were distributed in this area for coffee bean production. This is the origin story of so-called "French Mission coffee."

Historically, coffee seeds from La Réunion island were spread by French missionaries. French Mission was considered another name for Bourbon coffee. However, current genetic testing has confirmed that SL-34 has Typica genetic group. The original legend that SL-34 was selected from French Mission coffee groups is likely incorrect. SL34 is a mutation between Typica and Bourbon, distinguished from SL-28 by its copper-colored young leaves. This indicates the variety is closer to the Typica variety. SL34 has strong resistance to heavy rain at high altitudes, with high coffee quality, featuring citrus acidity and rich mouthfeel.

FrontStreet Coffee: Kenya Thathini Estate Washed AA

Origin: Kiambu Region
Estate: Thathini Estate
Altitude: 1650 meters
Grade: AA
Variety: SL28, SL34
Processing Method: Washed processing

Roasting Curve

FrontStreet Coffee Barista Brewing Suggestions

Dripper: Hario V60
Water Temperature: 90°C
Dose: 15 grams
Ratio: 1:15
Grind Size: Medium-fine grind (EK43s setting 10)

Brewing Method Sharing - Segmented Extraction

Use 30g of water for bloom for 30 seconds. When pouring to 125g with small water flow in circular motion, segment the extraction. When the water level drops and is about to expose the coffee bed, continue pouring to 225g and stop pouring. When the water level drops and is about to expose the coffee bed, remove the dripper. (Timing starts from bloom) Extraction time is 2 minutes.

FrontStreet Coffee Kenya Hand-pour Coffee Flavor Description

Distinct black plum, cherry tomato, honey, with slight nutty notes when cooled, juice-like mouthfeel, bright acidity.

Ruiru 11

In 1985, during the global coffee leaf rust outbreak, Kenya developed this hybrid variety focused on yield rather than quality. However, its flavor quality is far inferior to the previous SL28 and SL34, so it hasn't developed in the specialty coffee industry. However, many suppliers, even those importing famous coffee, mix this hybrid bean into blends to reduce costs.

Kenyan Coffee Grading

Kenyan coffee beans began using a strict grading system in the 1930s, mainly based on coffee bean size, shape, and hardness. From high to low, they are classified as AA or AA+, AB, PB, C, E, TT, T. This can be used as a reference when selecting, and coffee flavor is also considered. Currently, common grades in the mass market are AA, AB, and PB.

E (Elephant Bean)

Here "E" represents "Elephant," but this is not the elephant bean variety among coffee bean types. Rather, it's a defect caused by abnormal development where two seeds intertwine, forming what appears to be a single bean. Generally, one fruit contains two seeds facing each other, so one side is flat, called flat beans, female beans, or twin beans. E grade beans are where two seeds fuse together during growth, becoming extra-large beans. E grade beans are about 18 screen (one screen = 1/64 inch) or larger and are rare.

AA

This grade is about 17-18 screen (approximately 6.7-7.1mm). It's the most commonly heard Kenyan coffee grading. In specialty coffee, this grade is usually called AA TOP and is the bean most coffee shops promote. However, AA doesn't necessarily mean the best - this only refers to bean size and shouldn't be confused with flavor.

AB

Most coffee beans fall into this grade. It's called AB mainly because A grade filter holes are 6.80mm and B grade are 6.20mm. These two sizes of coffee beans (A and B grades) are mixed together for sale, hence called AB. The size is about 15-16 screen (approximately 6.0-6.4mm).

C

This grade includes beans about 14-15 screen (approximately 5.6-6.0mm), smaller than B grade.

PB

In English called Peaberry, in Taiwan mostly called small round beans, but can also be called male beans or single瓣 beans. Compared to regular flat beans, these are also quite rare, accounting for about 10% of all coffee beans. This occurs when only one seed develops inside the fruit, resulting in small, round beans. Some people particularly love PB flavor, so PB beans are selected and sold separately.

TT

This category includes light beans selected from AA and AB beans using air separators. They usually have light weight, don't meet hardness standards, and include broken and defective beans.

T

These are lighter-weight beans selected from C grade beans, mixed with damaged beans and even coffee bean fragments.

MH/ML

This category of coffee beans is not exported. They are usually overripe coffee beans that have fallen to the ground, with poor quality, accounting for about 7% of all coffee beans, only for the Kenyan domestic market.

Kenyan Coffee Grading - Where do AA TOP and AB TOP come from?

In fact, besides the official version of Kenyan coffee grading, Kenyan exporters or traders have created special classifications for AA and AB (unofficial). Common ones include: AA TOP, AA+, AA++, AB+, AB TOP, and AA FAQ Kenyan coffee grading.

FAQ

FAQ is short for "Fair Average Quality," meaning average fair quality, representing the basic version of AA grade. However, classifications like AA TOP, AB TOP, AA+ don't have specific standards. It's not necessarily true that more "+" signs mean better taste or flavor. Why?

The main reason is that this isn't a unified standard. Different green bean traders or different people will produce different results. It's possible that Company A's AA+ might be equivalent in flavor to Company B's AA++. Therefore, everything ultimately comes back to cupping when you roast - that's the most practical approach!

Kenyan Processing Methods

Just as honey processing is characteristic of Costa Rica and wet-hulling is characteristic of Indonesia, how can we discuss Kenyan coffee without mentioning the K72 processing method?

Kenyan 72-Hour Fermentation Washed Processing Method

Originating in Kenya, this method uses repeated cycles of fermentation followed by washing. Processing begins on harvest day, selecting the highest quality cherries for pulping and fermentation. Fermentation time is 24 hours, after which clean river water is used for washing. Then, the beans undergo another 24-hour fermentation in clean river water, followed by washing again. After repeating this cycle 3 times for 72 hours, it's called the Kenyan 72-hour fermentation washed processing method, abbreviated as K72.

First Washing and Fermentation

After coffee cherries are harvested, they first undergo water density sorting. The principle uses the density and quality differences of the coffee fruits themselves for selection; high-density (heavy) coffee beans sink in water, while low-density beans float. Fully ripe, high-quality coffee fruits have high density, and they are selected for further processing.

After selecting high-quality, sufficiently ripe fruits, the skin is removed and the beans are soaked in water for washing, allowing the mucilage attached to the outer layer of the green beans to ferment. The mucilage contains natural sugars and alcohols that play a crucial role in developing the coffee's sweetness, acidity, and overall flavor. The fermentation time lasts up to 24 hours, after which 80-90% of the mucilage is removed, leaving only the flavor within the coffee beans.

Second Washing and Fermentation

Next enters the second washing and fermentation process. After the coffee beans from the previous stage are cleaned, they are soaked again in water for 24-48 hours. This process increases proteins and amino acids, creating complex and delicate layers of acidity in the coffee beans. Finally, all remaining mucilage is removed, and the coffee beans are moved to raised racks for sun drying.

The fermentation time lasts up to 24 hours, after which 80-90% of the mucilage is removed, leaving only the flavor within the coffee beans.

Finally, all remaining mucilage is removed, and the coffee beans are moved to raised racks for sun drying. The drying time depends on weather conditions, generally taking about 5-10 days to complete.

How Many Coffee Regions Does Kenya Have?

Kenya has seven famous coffee regions: Thika, Kirinyaga, Mt. Kenya West, Nyeri, Kiambu, Ruiri, and Muranga. The foothills of Mt. Kenya and Aberdare are the main growing areas.

Each region in Kenya has very different flavors. Kenya is divided into 47 counties. Coffee from different counties has distinct characteristics. Kenyan coffee trees are mostly grown at altitudes of 1400-2000 meters, with two harvests per year. Growing regions include Ruiri, Thika, Kirinyaga, Mt. Kenya West, Nyeri, Kiambu, and Muranga, mainly on the foothills of Mt. Kenya and Aberdare. For example, FrontStreet Coffee, through cupping, found that coffee from the Embu region has balanced mouthfeel with citrus fruits, chocolate, apples, and acidity; while coffee from the Nyeri region often features white grapes, juicy mouthfeel, grapefruit and cherry tomato flavors, full of fruitiness and sweet as caramel.

Major Kenyan Coffee Regions:

NYERI

Located in central Kenya, Nyeri is home to the dormant volcano Mount Kenya. This region's red soil nurtures Kenya's best coffee. Agriculture is extremely important here; coffee is the main crop. Cooperatives composed of small farmers are more common than large estates. This region has two harvests, but coffee from the main season is usually higher quality. This region is known for its solid blackberry-like acidity and floral and fruity aromas.

Altitude: 1200-2300 meters
Harvest Period: October-December (main season), June-August (secondary season)
Varieties: SL-28, SL-34, Ruiru 11, Batian

MURANG'A

This region in Central Province has about 100,000 coffee farmers. This region, not far from Nairobi, was one of the first settlement areas chosen by missionaries because the Portuguese prohibited them from living in coastal areas. This is another region benefiting from volcanic soil, with more small coffee farmers than estates. It has brighter acidity.

Altitude: 1350-1950 meters
Harvest Period: October-December (main season), June-August (secondary season)
Varieties: SL-28, SL-34, Ruiru 11, Batian

EMBU

This region near Mount Kenya takes its name from Embu city. About 70% of the local population engages in small-scale farming, with tea and coffee being the most popular cash crops. Almost all coffee comes from small farmers, making this region's production relatively small. The acidity is not as pronounced as Nyeri, but the flavor is well-balanced.

MERU

Most coffee in this region is grown by small farmers on the foothills of Mount Kenya and the Nyambene Hills. The name refers to both the magnetic field area and the Meru people who live there. In the 1930s, they were among the first Kenyans to start producing coffee, due to the 1923 Devonshire White Paper which guaranteed the importance of rights for people of African descent in Kenya.

Altitude: 1300-1950 meters
Harvest Period: October-December (main season), June-August (secondary season)
Varieties: SL-28, SL-34, Ruiru 11, Batian, K7

KIAMBU

This region in central Kenya has the highest altitude coffee growing areas within the region, and Thika also belongs to this region. However, some coffee trees at high altitudes suffer from dieback disease, stopping their growth. This region is named after Nakuru town. Coffee cultivation here includes both estates and small farmers, though production is relatively small. This region is a traditional tea-growing area, with coffee beans having vanilla and floral aromatics.

Altitude: 1850-2200 meters
Harvest Period: October-December (main season), June-August (secondary season)
Varieties: SL-28, SL-34, Ruiru 11, Batian

KISII

This region in southwestern Kenya, not far from Lake Victoria, is a relatively small growing area, with most coffee beans coming from cooperatives composed of small producers.

Altitude: 1450-1800 meters
Harvest Period: October-December (main season), June-August (secondary season)
Varieties: SL-28, SL-34, Blue Mountain, K7

TRANS-NZOIA, KEIYO & MARAKWET

This small region in western Kenya has begun developing in recent years. Mount Elgon provides considerable altitude, with most coffee coming from estates. Coffee cultivation usually aims to diversify farms that previously only had corn fields or dairy products.

Altitude: 1500-1900 meters
Harvest Period: October-December (main season), June-August (secondary season)
Varieties: Ruiru 11, Batian, SL-28, SL-34

KIRINYAGA

This region sits on the slopes of Mount Kenya, near Nyeri, known worldwide for coffee with intense, layered flavors and solid mouthfeel. Together with Nyeri, it's recognized as currently Kenya's two best producing regions. Most producers in this region are small coffee farmers who join cooperatives. The cooperatives play a coordinating role, providing washing stations where coffee farmers send coffee cherries for green bean processing. The region originally referred to Mount Kenya, but British colonists found this name difficult to remember and changed the mountain name to Mt Kenya, no longer calling it Kirinyaga. It comes from the Kikuyu people, meaning "white mountains," considered the dwelling place of gods. The Kikuyu are Kenya's most populous ethnic group, accounting for one-fifth of the total population.

Altitude: 1300-1900 meters
Harvest Period: October-December (main season), June-August (secondary season)
Varieties: SL-28, SL-34, Ruiru 11, Batian

For more specialty coffee beans, please add FrontStreet Coffee on private WeChat, WeChat ID: kaixinguoguo0925

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473