I got up early this morning and sample roasted four Kenyans from Cafe Imports. The guys from Hanson are coming in this afternoon to taste them and potentially sell one of them on their website. I hope.
I'm doing a little research, so I don't sound so ignorant if they ask questions. Thought I'd share with you.
As far as I can tell, there are 8 grades of coffee coming out of Kenya.
AA is the highest grade, but all it really means is th
at it is a 18 or 17 screen (18/64 or 17/64 inch).
AB is a 16 screen.
PB - Peaberries are sorted out and make up about 10% of the crop.
C grade is smaller than AB.
TT is the size of AA and AB, but are less dense, and separated via air pressure.
T grade are very light and broken pieces.
It appears there are two other grades of coffee, but I'm not certain what they are. I'm sure at least one of them is a designation of domestic consumption coffee.
Most coffee produced in Kenya is Arabica. But there are many, many different varietals grown there. The French Mission Varietal is one of the oldest types of coffee in Kenya. It is a Bourbon strand brought over from Reunion Island by French missionaries in the late 1800s. Bourbon coffee developed (sort-of) naturally. The British East India Company sold seeds from Aden, Yemen to the French, who planted them on the island of Bourbon (which is now called Reunion). After a few generations on the island it took on unique characteristics. It is generally more "robust" than Typica and tends to have a higher production. The trees and cherries have a distinctive look, as well.
Some hybrid varietals are grown in Kenya. SL-28 was created by Scott Labs from Bourbon and Ethiopian Mokka varietals. (From Sweet Maria's site:) "It supposedly is selected from Tanganyika DR cultivar, found by A.D Trench on a trip through Tanzania, and has similar drought resistant properties. DR is of French Mission Bourbon origin. Many prefer SL-28 to the other successful... cultivar SL-34." I don't know who A.D. Trench is and I can't seem to find anything on the internet about him.
SL-34 is another hybrid produced by Scott Labs. (Again from Sweet Maria's:) "It supposedly is selected from French Mission Bourbon trees at Loresho Estate in Kabete Kenya. SL types are responsible for 90% of Kenya coffees. SL-34 has better yields than SL-28, and is grown at lower altitudes than SL-28." Generally, a higher-yielding varietal that produces well at lower elevations doesn't taste as good, so that's my assumption.
RUIRU 11: "is named for the station at Ruiru, Kenya where it was developed in the '70s and released in 1986. The initial tests were with Hibrido de Timor (a cross between Arabica and Robusta, resistant to Coffee Leaf Rust) and Rume Sudan, an original coffee strain resistant to Coffee Berry Disease. Later they added SL-28 and SL-34 inputs due to poor cup character of the early tests. The Robusta content of Ruiru 11 is still an issue, and the cup does not match the quality of the SL types."
Here is a map of Kenya with the growing regions highlighted.