Kenya is well known for its highly organized network of coffee cooperatives. This system produces remarkable consistency in growing methods, milling, and auctioning across a web of about 150,000 growers, the majority of which are small-scale farmers. The topography of high-altitude plateaus in major Kenyan coffee regions combined with acidic soil provides excellent growing conditions for Arabica.
All Kenyan coffee is graded primarily by screen size (a measure of the size of the bean, larger being higher grade) immediately after milling; it then proceeds to the weekly auction at the Nairobi Coffee Exchange. The AA Grade is the top grade based on screening. After grading, there are two general quality distinctions for AA:
Top Quality or Plus
Only a minimal amount of slight defects allowed as long as no effect on the cup. Typically grown at 4500-6000 ft above sea level, of SL-34 variety. Very high-quality coffees often derive from small co-ops and may be auctioned as separate lots.