Located within Kiambu County, Mchana Estate was once described as a “little paradise.” While a paradise it may be, very few would describe the sprawling 906 hectare estate as little. Nearly 500 hectares of the land is in active production, which makes Mchana Estate one of the largest estates in all of Kenya. Historically the estate has produced a vast amount of traditionally washed coffees (in line with the production of Kenya.) The rest of the coffees were processed as M’buni, a lower quality coffee that is generally sold to local markets or lumped in within larger lots for a low price. Thanks to the guidance of Mr. Wambungo, the estate has run several experiments ranging from Honey processes to full naturals. The estate's commitment to quality doesn't stop with coffee, they are committed to employing nearly 200 permanent employees, while supplying hospital care, child care, and stringent education in harvesting coffee.
NATURALLY PROCESSED COFFEE
Natural coffees are beautiful…Okay, natural coffees are beautiful when done properly, but can be equally terrible when things go wrong. Natural processing, or dry processing, refers to the act of drying and fermenting coffee inside the cherry. Long before the age of portafilter tattoos and dual-boiler home espresso machines, coffee was picked and dried this way out of convenience. It is, to this day, still the most convenient and economically friendly way to process coffee cherries. (It’s estimated that dry-processing can use up to 90% less water than the washing process.) So why isn’t all coffee processed this way? Well, as coffee made its way across the world, it was commoditized and standardized, just like all other products spread by colonialism, but that’s a whole other story... Adding to the boom of washed processing, the natural process method can be tricky to get right, due to the delicate nature of fermentation and drying. What does all this have to do with the final cup? Well, when you leave the skin and fruit of the coffee cherry on the seed throughout fermentation and drying, that fruit begins to break down, imparting esters that lend delicate florals and big fruit notes into the seed that will survive the roasting process. If it’s rushed or handled incorrectly, this fruit rot can lend off-flavors to the coffee, making the final cup dirty or ‘fermenty.’ Basically, that single cherry begins to slowly decay, and controlling that delicate action through advanced technique and metrics allow us to drink wonderfully floral and fruity coffees.
In the Kenya process, first, the cherries are sorted, and under-ripe/overripe cherries are removed. Once the sorting is finished, the coffee is then depulped. This is done by squeezing the cherry through a screen and removing the fruit and skin from the bean. The coffee is then left to ferment in white ceramic tiled tanks for 24 hours. Next, the coffee is stirred for a short amount of time and left to ferment for another 24 hours. After two days of dry fermentation, the coffee is washed with fresh water, removing the sticky mucilage attached to the beans that are loosened by bacteria during the fermentation. It’s then soaked in water to ferment overnight slightly. The coffee goes through sorting and density channels, which separates the lots, and then it is taken to raised beds to dry. Once it reaches 11.5-12% moisture content, the coffee is brought to conditioning bins to rest until it goes to the dry mill.
Once a coffee has been processed, dried, and then milled, it goes to a sorter that separates the beans by specific characteristics, mainly size. Coffee goes into a machine that vibrates, sending beans through different screens with different-sized holes and sorts the coffee based on size and density. This results in a more uniform coffee and cup profile. Then the coffees are auctioned based on the grade (size & density) they have.
AA (screen size 17 & 18)
The largest and most celebrated grade of Kenyan coffee. Usually the highest priced coffee on the auction from each outturn and factory. AA is the most common grade we buy and what we normally expect from an outstanding Kenya cup.
AB (screen size 15 & 16)
This grade represents about 30% of Kenya production. While AB is usually considered lower quality than AA, we find that to not be accurate in the cup. Over the years of cupping, we have consistently found incredible AB’s that actually cup better than their more prestigious AA relatives, enforcing the idea that everything must be cupped and not have its value determined based on classification or reputation.
Peaberries represent about 10% of Kenya production. They are a result of a coffee cherry only producing one bean instead of two. Technically they are fused together during early stages and form one round bean instead of two half spheres. We tend to notice more fermentation tasting notes here. Winey, syrupy, and mouth coating are some of the attributes that we usually notice in the cup.
E (large Peaberries & large chipped beans)
C (screen size 14 & 15)
TT (falls through 14)
T (small or broken pieces of beans)