Life of a Coffee Bean
24 September 2019
While our new Emporio takeout cups tell the coffee story, from plant to cup, Emporio owner Eric Heycoop takes us even closer to the action with a description of the life of a coffee bean.
Photos are mostly from Eric and Miriam's trip to visit their coffee growers in Nicaragua, with extra information sourced from the National Coffee Association USA.
Coffee growing and ripening
A coffee bean is actually a seed from the coffee tree, which is then dried, roasted and ground to brew coffee. If the seed isn’t processed, it can be planted and grown.
Coffee beans are found in coffee cherries, the fruit of a coffee tree. Each cherry usually contains two beans.
Cherries take up to six years to grow and ripen on the coffee tree, they begin life as small white flowers before turning into buds. The cherries are ripe and ready for harvest when they turn red.
Each coffee tree can produce fruit for about 20 years with each tree yielding around 40,000 beans during its life time.
Typically, there's one major harvest a year but in countries like Colombia, where there are two flowerings annually, there is a main and secondary crop.
Crops are mostly picked by hand, a labour-intensive process. Whether by hand or by machine, all coffee is either strip or selectively picked:
Strip Picked: All the cherries are stripped off the branch at one time, either by machine or by hand.
Selectively Picked: Only the ripe cherries are harvested, and they are picked individually by hand. Pickers rotate among the trees every eight to 10 days, choosing only the cherries which are at the peak of ripeness. Because this kind of harvest is labour intensive and more costly, it is used primarily to harvest the finer Arabica beans.
The cherries are then sorted to remove any less than optimal fruit that may have slipped in.
Once the coffee has been picked, processing must begin as quickly as possible to prevent fruit spoilage. Depending on location and local resources, coffee is processed in one of two ways:
The Dry Method is the age-old method of processing coffee, and still used in many countries where water resources are limited. The freshly picked cherries are simply spread out to dry in the sun. To prevent the cherries from spoiling, they are raked and turned throughout the day, then covered at night or during rain.
The Wet Method removes the pulp from the coffee cherry after harvesting so the bean is dried with only the parchment skin left on. First, the freshly harvested cherries are passed through a pulping machine to separate the skin and pulp from the bean. The beans are separated by weight as they pass through water channels. The lighter beans float to the top, while the heavier sink. They are passed through a series of rotating drums which separate them by size.
After separation, the beans are transported to large, water-filled fermentation tanks. They remain in these tanks for 12 to 48 hours to remove the slick layer of mucilage (called the parenchyma) that's still attached to the parchment. While resting in the tanks, naturally occurring enzymes will cause this layer to dissolve.
When fermentation is complete, the beans feel rough to touch. The beans are rinsed by going through additional water channels and are ready for drying.
If the beans have been processed by the wet method, the pulped and fermented beans must now be dried to approximately 11% moisture to properly prepare them for storage.
The beans, still inside their parchment envelope (the endocarp), are spread on drying tables or floors and turned regularly, or they can be machine-dried in large tumblers.
Milling and Export
The dried beans are now known as parchment coffee and are warehoused. Just before being shipped, the beans are first milled, either by processes called hulling or polishing. The milled beans are now known as green coffee and are packed in jute sacks ready for export.