What Gives Kenyan Coffee Beans Their Bright Acidity?

Kenyan coffee earns its juicy, berry-like character from three things working together: the high-altitude terroir around Mount Kenya and the East African Rift Valley, the SL-28 and SL-34 varieties, and the K72 double washed processing method. Together they produce the bright fruit acidity alongside a thick, coating mouthfeel that sets Kenya apart.

Kenya sits on the equator with two rainy seasons, so it harvests two crops each year: roughly 60 percent from October to December and 40 percent from June to August. Coffee grows mainly in the volcanic highlands, where average altitude reaches about 1,500 meters. For drinkers who prefer that acidity, iced pour-over, iced drip and cold brew all work well.

Kenyan coffee is famous for its bright, uplifting fruit acidity and its full, thick berry-juice body. Where exactly does this unique flavor come from? This article analyzes the causes of Kenyan coffee's flavor from three dimensions: origin terroir, the characteristics of the SL-28 and SL-34 varieties, and the K72 double washed processing method. It also introduces in detail the flavor performance of two representative Kenyan beans in Front Street Coffee's stores, Asalia and Little Tomato. In addition, in response to the prominent acidity of Kenyan coffee, the article shares the specific brewing parameters and operating steps for three iced coffees: iced pour-over, iced drip, and cold brew, making it suitable for coffee lovers who enjoy fruity acidity to refer to and practice.

For more specialty coffee knowledge, please follow the WeChat public account: Front Street Coffee (FrontStreet Coffee)

Front Street Kenyan coffee's bright, uplifting fruit acidity, combined with its vivid and full mouthfeel, leaves a deep impression on anyone who has tasted it. Front Street has cupped many beans from various Kenyan producing regions. If high acidity can be called the soul of good coffee, then Kenya is undoubtedly the embodiment of that soul. Kenyan beans also have another distinctive trait: most coffees with bright acidity often lack a substantial mouthfeel. For example, Ethiopian beans give a clean and refreshing impression on the palate, while Kenyan coffee can form a berry-juice texture in the mouth with a full sense of coating, rich like tomato juice.

Kenyan Coffee Cultivation

Kenya is located in eastern Africa, with the equator passing through its center and the East African Rift Valley running north to south. It borders Somalia to the east, Tanzania to the south, Uganda to the west, Ethiopia and Sudan to the north, and faces the Indian Ocean to the southeast. Highlands are widespread throughout the country, with an average altitude of about 1,500 meters. Mount Kirinyaga (Mount Kenya) in the center has an altitude of 5,199 meters, and its summit is covered with snow year-round, making it the second-highest peak in Africa.

Kenya is a tropical producing region with two rainy seasons each year, so it can also harvest two crops, with 60% concentrated from October to December and the other 40% from June to August. Coffee is mainly grown in the volcanic zone at altitudes of 1,600 to 2,100 meters from the capital Nairobi to the surrounding Kenyan highlands. This altitude is favorable for the development of coffee bean flavor because temperatures in the highlands are lower, the beans grow slowly, aromatic substances can fully accumulate, the fruity acidity is more prominent, and the texture is also harder. This fertile coffee zone shaped like a crescent moon is precisely the core producing area of Kenyan specialty beans.

In the specialty coffee wave, variety is regarded as a key factor affecting flavor in the cup. The flavor performance of Kenyan coffee is inseparable from the two varieties SL-28 and SL-34.

SL stands for Scott Labs. In the 1930s, the laboratory was commissioned by the Kenyan government to conduct coffee breeding and classification research, with the goal of finding varieties that could adapt to Kenya's terroir, be suitable for large-scale cultivation, and have commercial value. SL-28 and SL-34 are two among many research results.

Kenya belongs to the African producing regions, and high-quality Kenyan beans basically all use the washed processing method. Combined with meticulous roasting, this can better showcase the region's distinctive lemon, citrus, and grapefruit flavors, with a refreshing mouthfeel and a slight sweet-and-sour quality.

Kenya's unique processing method is called the "double washed method," also known as "K72" washed processing. Its core lies in making the coffee beans undergo two fermentations. The process of Kenyan double fermentation is: floating selection of coffee cherries, removal of pulp, fermentation overnight in the upper fermentation tank, washing, transfer of parchment beans to the lower fermentation tank for continued fermentation for 36 hours, washing again, and sun drying.

The washing channels of the double fermentation method are divided into upper and lower levels, used respectively for the first and second washing. After harvesting the coffee cherries, defective fruits and fruits with insufficient density are first removed, the skin is removed, and they are poured into the upper fermentation tank for fermentation; dry fermentation without putting them into the tank can also be used directly. The length of fermentation is affected by many factors; the hotter the environment, the faster the fermentation. After fermenting for a period, most of the pectin is removed by washing, and then the beans are placed in the lower clean-water tank for a second fermentation. It should be noted that during fermentation, the circulating water must be changed every few hours to prevent the coffee beans from becoming foul-smelling.

The coffee beans are washed again with water to remove residual pectin. The second fermentation plus rinsing takes 36 hours, but this is not the end. If the coffee beans are soaked too long during fermentation, negative flavors will increase. Once it exceeds 36 to 72 hours, over-fermentation may occur and fatty acids may be produced, making the coffee taste too sour. Therefore, this process takes about 12 hours or more. In other words, the entire Kenyan washing process takes at least 48 hours, and can even last as long as 72 hours.

Kenya's unique double fermentation washed method enhances the original acidity and cleanliness, because during the washed fermentation process, the acetic acid concentration of the coffee beans increases, thereby strengthening the coffee flavor.

Kenya's unique washed processing, combined with appropriate roasting, presents very obvious berry-type flavors. One coffee from the Asalia processing plant in Front Street Coffee (FrontStreet Coffee)'s stores has distinct blackcurrant, grapefruit, and slight cherry tomato flavors. The baseline of high-quality Kenyan coffee is mostly pronounced acidity and uplifting acidity quality.

If you prefer berry-acidity flavors, Front Street Little Tomato coffee beans are usually recommended. This is a classic Kenyan single-origin coffee. It not only uses K72 washed processing, but its varieties also consist of SL28 and SL34, and it comes from the region's highly representative high-altitude producing area, Thika. After Front Street uses a medium-light roast, it shows a dense and full berry flavor and fragrant floral notes, along with a cherry tomato flavor running throughout, making it suitable for extraction in multiple ways.

What kind of coffee is Kenyan coffee suitable for making?

As introduced earlier, high-quality Kenyan coffee mostly has pronounced acidity, lingering berry flavors, and uplifting acidity, so it is very suitable for enthusiasts who like coffee with acidity. Also because of its prominent acidity, Kenya is especially suitable for making iced drinks, such as iced pour-over, iced drip, cold brew, and so on.

How do you brew iced pour-over coffee?

Front Street Coffee (FrontStreet Coffee)'s iced pour-over approach is: extract a low-ratio coffee liquid (high concentration), then dilute it by adding ice cubes.

The amount of coffee powder is 15g, the powder-to-water ratio is 1:10, the ice amount is 75 grams, the water temperature is 92°C, and the grind level is medium-fine (EK43s setting 9.5, 80% passing through a 0.85 mm sieve).

First, put 75g of ice cubes into the server, then pour 15g of ground coffee into the dripper and gently tap it level. In the first stage, pour 30g of hot water from the center outward in a small circle with a slow flow of 3-4 ml/s and bloom for 30 seconds; after 30 seconds, pour the second stage of 60g of water using the same technique, taking care not to raise the water level too high, as this can easily cause under-extraction; when the coffee liquid is about to run dry, pour all the remaining 60g of hot water at a flow rate of 3 ml/s, ensuring the extraction time falls within 1 minute 50 seconds to 2 minutes.

The ice molds we usually use at home are mainly spherical and square. Because they use static freezing, they are both solid ice. In the same shape, the larger the volume, the slower it melts, though the corresponding freezing time is also longer. In addition, ice that has been refrozen has greater hardness, and when put into coffee it has a better cooling effect than fresh ice just unmolded after freezing.

For friends who like to drink iced coffee at home, Front Street suggests choosing slightly larger ice cube trays when buying them, or a single large spherical mold, so the ice made is firmer. If the ice tray you are using is on the small side, you can unmold the ice cubes in advance and store them in a clean container to keep the ice harder.

Then pour the extracted coffee liquid into the ice cubes and shake to mix. Cover the sharing pitcher with its lid: on one hand, this reduces the volatilization of aroma molecules; on the other hand, it allows the coffee liquid to be poured out without ice cubes mixed in.

Because iced pour-over coffee is a low-ratio extracted coffee liquid diluted with ice cubes, at the beginning it is a relatively concentrated coffee liquid with a full and solid mouthfeel. As the ice cubes melt and dilute it, the mouthfeel tends toward smoothness, and the flavor shifts from complex to refreshing.

How do you make iced drip coffee?

Front Street's iced drip plan is to use 60 grams of coffee powder to extract 600 milliliters of coffee liquid. The powder-to-liquid ratio is 1:10. The drip rate is about 3 drops every 10 seconds, using an ice-water mixture as the water source in the upper chamber. The extraction time is about 8 hours. After extraction, put the coffee liquid into a sealed bottle and place it in the refrigerator for 48 hours.

How do you make cold brew coffee?

Front Street's cold brew plan is to use 50 grams of coffee powder, with a powder-to-water ratio of 1:10, meaning 500g of drinking water needs to be poured in. Stir it thoroughly with the powder, make sure it is sealed, and then place it in the refrigerator to chill for 8-14 hours.

When the soaking time is up, take it out and filter out the coffee grounds cleanly with filter paper, then pour it into a clean sealed bottle. If you want a richer coffee flavor, you can put it back in the refrigerator for another 3-4 hours to settle. The Little Tomato cold brew made this way has a refreshing, pleasant taste, with a slight sweet-and-sour finish, and is especially suitable for drinking in summer.

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