The aroma that envelopes you when opening a pack of fresh coffee really is one of life’s little pleasures isn’t it? But what do you actually know about coffee and how it came to be in your cup? Well, if you’re sitting comfortably, we’ll begin at the very beginning – with one single arabica coffee bean growing around 5,000ft above sea level in the highlands of Nyeri, nestled between the Aberdare Mountain range and Mount Kenya, in East Africa.
Well, for a start, our coffee bean isn’t actually a bean. It’s the seed in a cherry of a coffee plant. People call it a bean because, well, it looks like a bean, and usually there are two inside each cherry, though a few cherries do contain single coffee beans that are known as “peaberries”.
Our coffee bean has been growing happily inside its cherry, which slowly ripened and turned red. It was then picked by hand and placed in the cherry hopper at the mill.
There are two principal ways to process coffee – by the dry process, also known as the natural method, or the wet process, also referred to as the fully washed method. The wet process involves removing the skin and the pulp from the cherry before drying.
The wet mill is at the nearby Gikanda Farmers Co-operative, a Fairtrade certified coffee producer. Here the hand-picked coffee cherries are pulped. Pulping needs to be done as soon as possible after harvesting and involves the coffee beans being added to water and then passed through vertical spinning discs to remove the skin and some of the pulp. Our coffee bean, still in its “parchment” coating, is swept along by water with other beans and over a screen that moves back and forth. Good quality dense beans like ours sink and fall through the screen, and poorer quality light beans float across the top. These two grades of coffee are then separated into different fermentation tanks.
Our coffee bean, along with its high quality company, is then left to ferment – that’s when naturally occurring enzymes in the remaining fruit of the cherry get to work breaking it down. Knowing when to stop fermentation is crucial as over fermenting can result in a flavour of rotten fruit. So as soon as the parchment feels rough, not slimy, the beans are ready, and they’re washed in fresh water.
The best grades of parchment coffee are improved by being soaked in tanks of water for anything from twelve hours to seven days and water is replenished every twelve hours. Once the beans have soaked, they are transferred to the skin drying tables. This is when they get their “coffee passports” that carry a reference number and details of the dates that the cherry was received and fermentation was completed.
The waist high drying tables let air circulate around the parchment coffee for a day until surface moisture has evaporated, leaving a moisture content of around 45-55%. After skin drying, our arabica coffee bean is moved to a drying table where its moisture is carefully monitored.
Only mad dogs and Englishmen go out in the midday sun, and coffee is sensitive too, so beans are spread thickly on drying tables and covered during the hottest part of the day. This stops our coffee bean drying too quickly and its protective parchment casing from cracking. When its moisture hits 30%, the amount of coffee on the table is halved and spread much more thinly to get plenty of sun and dry to between 10-20% moisture.
Once moisture is at an optimum 12.5% the beans are placed in special conditioning bins – huge mesh containers that are raised off the floor to allow air to circulate freely. Here our arabica coffee bean will sit out of the sun in a stable environment waiting for its moisture content to settle and even out. Finally, just before auction and export, beans are sent for ‘curing’ where they are ‘hulled’ to remove the parchment. Finally, they are cleaned, screened, sorted and graded.
Then our bean waits for a buyer. This is also where we’ll leave you waiting… until the final part of our coffee bean’s journey in next week’s post. Any questions so far? Do leave a comment and we’ll get back to you.
