Coffee is the among the world’s top internationally traded commodities in terms of both volume and value; it is second only to oil. Coffee farming is very lucrative and rewarding. aThe fruits of coffee trees are cherries. Cherries usually contain two hemispherical seeds, though it is possible to find some with just one. These seeds are at the core of coffee harvesting; they are actually the highly famed coffee beans. The current global coffee production is at the most high. It is therefore apparent that coffee is on high demand and so farmers should aim at maximising their yield to tap into this lucrative industry. In order to maximise yields, great care has to be taken when harvesting coffee to avoid any damage that can minimise the overall produce.
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Coffee trees naturally take about 3 to 4 years to mature, however, improved varieties can mature between 1 to 2 years for example the Sigararutang beans which are said to be quick yielding. Such varieties can produce coffee throughout the year and are the most favoured by farmers. Although the overall coffee yield differs from place to place, experienced farmers harvest between 200 and 400 pounds of coffee per day at the peak of the season. The ideal time for harvesting coffee is in the region of 8 to 9 months after the coffee bush flowers. The total number of harvests vary in relation to climate and variety among other factors. Most areas record only a single harvest whereas some use the selective method of harvesting coffee thus record 2 or more harvests. The first harvest is termed the principal harvest and is considered as the main harvest. The second is called a secondary harvest whereby left over coffee is picked to supplement the principal harvest. Coffee beans should ideally be picked at the peak of ripeness when the cherry becomes red in colour. It is important to note that cherries do not mature simultaneously. A single coffee tree can have cherries in several stages of development. Farmers are advised to only select red cherries which are neither immature nor over-ripe. This is because immature and over-ripe coffee beans are of inferior quality and nothing can be done to salvage them. Another downside of harvesting coffee that is immature is that it does not have caliginous coating to protect it from damage. In spite of these recommendations, some farmers harvest cherries while still green due to the increased amount of beans found on green cherries. Ripe cherries contain about 800 to 900 beans whereas green cherries have roughly 1000 to 1200 beans, hence the choice of picking green cherries in a bid to maximise the overall yield.
Coffee harvesting is achieved in two ways, namely through strip picking and selective picking. These methods can either be done manually through hand picking or mechanically, employing the use of harvesting machinery. Like the namesake, strip picking involves removing all cherries from the tree regardless of the maturity level. Selective picking is basically the selection of ripe red cherries, allowing green cherries the opportunity to reach maturity before being harvested. Coffee harvesting done by selective picking involves frequent visits to the same tree for about 8 or more days until the completion of the harvest. Although selective harvesting is time consuming, it results in increased yields as immature cherries are allowed to mature.
Pulping involves the separation of the coffee fruit and the coffee beans. Pulping has to be done within 12 hours of harvesting coffee to maintain the quality of the coffee and to avoid damage. One of the common mistakes made by farmers is waiting for 48 hours and sometimes up to several days before coffee beans are pulped. Consequently, the mucilaginous coating of the bean is decomposed leaving the coffee beans vulnerable to damage during the pulping process. The heat generated by fermentation of the pulp results in discoloured and sour beans that are considered as defective.
This is an essential stage in harvesting coffee that allows efficient drying of coffee beans. After pulping, coffee beans are covered in a thick layer of mucilaginous matter which is very difficult to dry. Fermentation is the process of removing this mucilage. It is carried out in concrete tanks, wooden crates or jute bags. Coffee beans are left in clean water for 8 to 12 hours. In areas with low temperatures, this process can take up to 18 hours. After fermentation, the beans are washed with clean water for 2 to 4 times in order to remove any traces of mucilage. Mucilage can also be removed from coffee beans through mechanical means. A demucilager machine is recommended as it ensures constant quality and prevents over-fermentation.
Coffee is processed through the wet method also known as the washed method or the dry method which is often referred to as the natural method. Wet processing is a sophisticated method that involves placing harvested cherries in a de-pulping mill to remove coffee beans from the fruit. Afterwards they are immersed in moving water through sluice ways to wash the coffee. Once washed, the beans are partially kiln dried in rotating dryers and sun dried on terraces. Depending on the quantity of the yield and preference of the farmer, coffee can either be sun dried or employ kilns to fasten the process. Dry processing involves drying cherries on terraces before pulping. Sun dried coffee must be laid 2.5cm thick and turned every hour. Coffee beans should be dried until they reach a moisture content of 12%. Beans having moisture contents higher than 13% turn into an opaque white upon storage. Note that coffee with parchment dries after 9 to 10 days. Wet processing is highly recommended as it produces superior beans with fewer defects and a cleaner finish.
Hulling and Grading
Hulling is the process of removing the parchment from the coffee beans. Hulling machines are employed as this is an almost impossible task to achieve by hand. Care should be taken that coffee beans are not over heated during this process. Overheating impairs the quality of the coffee. Most farmers do not process their coffee up to this stage; they sell it to larger agricultural specialists who then finish processing the coffee. Coffee beans are polished soon after hulling. This is however an optional process. Polishing is done to remove the outer filament and any of the parchment that remains on the bean after hulling. Polished coffee beans are considered to be of superior quality. After the removal of parchment, coffee beans are graded according to shape and size (width, thickness and length).
Packaging and Storage
These are the final stages involved in harvesting coffee. Coffee beans are packed firmly into coffee baskets or in any aluminium free packaging which the highest environmental stability. This is done to avoid pressurization that leads to damage during brewing. As a result, the coffee will permeate unevenly. Coffee beans should be stored in a well ventilated dry rooms to avoid any last minutes defects. Excessively high and low temperatures will compromise the quality of coffee beans.
The overall coffee yield depends on a range on factors such as seed variety, climate, fertility of the soil and so forth. Traditionally grown coffee yields amount anywhere between 500 to 1000kg per hectare. On the other hand, coffee grown from improved varieties and modern technology constitutes double this amount. Yields can be as high 2300 to 3400 kg per hectare. Note that coffee yields often decline due to improper harvesting technques.
Coffee consumers do not compromise on the quality of their coffee hence the need for skilfulness when harvesting coffee. Only coffee without physical and sensorial defects is deemed worthy for consumption. Errors in the process of harvesting coffee can thus minimise production costing farmers a lot of time. For this reason, skilfulness is an asset that all coffee growers should possess so as to get the most out of their harvest.