Coffee Started out Green…
I may be wrong, but if you were like me, for the longest time I never knew that coffee started out green.
One story tells us that it was a goat shepherd who found his goats screaming across the pastureland. He traced their travel to some green shrubs with red berries, and after trying some, understood why his goats were wired.
The coffee plant is a perennial evergreen that belongs to a family of plants known as the Rubiaceae family. It can grow to very tall heights, so hence it is also called a tree.
There are two (2) types, or species of coffee which are cultivated today. There is coffee canephora (Robusta) and coffee arabica, aka Arabica coffee. Robusta accounts for 20% of the world’s consumption of coffee, but even though they are a more robust than their counterpart, its’ taste falls short and but has a higher caffeine content. Arabica, on the other hand, comprises the other 80% of the world’s coffee.
Beans on the Vine Coffee plants are planted much like Christmas trees, and after three or four years, they start producing sweet smelling flowers which are formed in the axils of the leaves themselves. It must be noted that the fruit portion (where the beans start growing) can only survive in the new tissue growth.
The main difference between the Robust and Arabica coffee plants is simple. Robusta relies on self-pollination for growth, whereas Arabica is self-pollinating.
Two months after fertilization, cell division is occurring and then the coffee flower continues growin, the speed and size of which are totally dependent upon the climate.
There is a lot of other technical stuff that goes on, but suffice it to say that you’d need to be a PhD in botany to grasp it all. But, after about 36 weeks after germination, the coffee bean turns from green to red, which signals that it’s almost ready to be picked.
The root system is vast, and there are horizontal and vertical root systems for each plant.
To be thick and strong, the coffee roots need an extensive supply of nitrogen, calcium and magnesium. During planting the main vertical roots are often clipped to promote growth of the horizontal roots, which then have better access to water and added nutrients in the top soil.
In most countries, the coffee crop is picked by hand, a labor-intensive and difficult process, though in places like Brazil, where the landscape is relatively flat and the coffee fields immense, the process has been mechanized. Whether picked by hand or by machine, all coffee is harvested in one of two ways:
The entire crop is harvested at one time. This can either be done by machine or by hand. In either case, all of the cherries are stripped off of the branch at one time.
Only the ripe cherries are harvested, and those are picked individually by hand. Pickers rotate among the trees every 8 – 10 days, choosing only the cherries which are at the peak of ripeness. Because this kind of harvest is labor intensive, and thus more costly, it is used primarily to harvest the finer arabica beans.
In the Wet Process, the fruit covering the seeds/beans is removed before they are dried. Coffee processed by the wet method is called wet processed or washed coffee .4 The wet method requires the use of specific equipment and substantial quantities of water.
After the Green coffee is picked the coffee is sorted by immersion in water. Bad or unripe fruit will float and the good ripe fruit will sink. The skin of the cherry and some of the pulp is removed by pressing the fruit by machine in water through a screen. The bean will still have a significant amount of the pulp clinging to it that needs to be removed. This is done either by the classic ferment-and-wash method or a newer procedure variously.
In the ferment and wash method of wet processing the remainder of the pulp is removed by breaking down the cellulose by fermenting the beans with microbes and then washing them with large amounts of water. Fermentation can be done with extra water or, in “Dry Fermentation”, in the fruit’s own juices only.
The fermentation process has to be carefully monitored to ensure that the coffee doesn’t acquire undesirable, sour flavors. For most coffees, mucilage removal through fermentation takes between 24 and 36 hours, depending on the temperature, thickness of the mucilage layer and concentration of the enzymes. The end of the fermentation is assessed by feel, as the parchment surrounding the beans loses its slimy texture and acquires a rougher “pebbly” feel. When the fermentation is complete, the coffee is thoroughly washed with clean water in tanks or in special washing machines.
Machine-assisted wet processing:
In machine-assisted wet processing, fermentation is not used to separate the bean from the remainder of the pulp; rather, this is done through mechanical scrubbing. This process can cut down on water use and pollution since ferment and wash water stinks. In addition, removing mucilage by machine is easier and more predictable than removing it by fermenting and washing. However, by eliminating the fermentation step and prematurely separating fruit and bean, mechanical demucilaging can remove an important tool that mill operators have of influencing coffee flavor. Furthermore, the ecological criticism of the ferment-and-wash method increasingly has become moot, since a combination of low-water equipment plus settling tanks allows conscientious mill operators to carry out fermentation with limited pollution.
Coffee Drying Beds
Any wet processing of coffee produces coffee wastewater which can be a pollutant. Around 130 liters of fresh water is required to process one kilogram of quality coffee.
After the pulp has been removed what is left is the bean surrounded by two additional layers, the silver skin and the parchment. The beans must be dried to a water content of about 10% before they are stable. Coffee beans can be dried in the sun or by machine but in most cases it is dried in the sun to 12-13% moisture and brought down to 10% by machine. Drying entirely by machine is normally only done where space is at a premium or the humidity is too high for the beans to dry before mildewing.