Coffee Process – Plant Propagation
Coffee seeds are pulped from the coffee cherry and planted in small plastic tubes. Once growth occurs, the seed pushes itself out of the ground, with stem and roots below. The seed eventually opens out into the first two leaves, with rapid growth following.
Grown under shade to ensure the tender growth is not burnt by direct sun, the sapling coffee plant continues to grow with twin opposing leaves up the stem, until the first branches appear.
Within six-eight months, the young trunk has hardened and is ready to be planted in the open plantation.
Coffee Process – Plantation Management
Depending on altitude, geographic form and harvesting method (hand-picked or machine harvest), the coffee trees will be planted close together or more apart.
- Hand Picking requires 360 degrees access around the tree to enable a greater yield of coffee cherries per tree, and helps to ensure more even ripening. Steep mountain plantations do not allow mechanical harvesting, where hand picking is the only method of cherry removal
- Machine Harvesting requires the coffee trees to be planted close together forming hedge rows that allows the harvester to travel down during harvest season. While the yield per tree is reduced the method allows more trees to be planted per hectare, resulting in an overall better yield/hectare.
Coffee Process – Handpicking
Handpicking occurs when the coffee cherries are ripe, and when they are ready to fall off the tree easily, and in their best condition to offer the coffee flavour characteristics later when they are roasted. Careful handpicking of only ripe cherries means that some trees may require 2-3 harvest visits, to remove all the cherries as they continue to ripen.
Mass removal, known as ’cherry stripping’ or ‘strip picking’, is where both ripe and un-ripe cherries are removed at the same time. Though less labour intensive if the ripe and unripe cherries remain together throughout the remaining process, the result is a lesser quality coffee, Alternatively, the unripe cherries may be removed before processing to better maintain the quality finish and consistency of the bean going to the global market.
Coffee Process – Machine Harvesting
Machine harvested coffee cherries are delivered to the processing plant in tip-trailers pulled by tractors from the fields. The mechanical harvesters use hundreds of flexible vibrating rods, which slowly turn as they pass down the hedgerows. These rods pass within the branches slowly tickling the ripe coffee cherry off the stems of the trees.
Green or unripe coffee cherries are generally not removed from this process as they still have a stronger bond with the branches, where they are left to ripen, and to be harvested by another harvest pass later in the season. Conveyor belts inside the harvester deliver the coffee cherries into an onboard holding bin, which empties into a trailer or via an auger drive directly into a following trailer. It is these trailer bins that are constantly ferried back to the processing plant, from across the plantation.
Coffee Process – Winnowing
It is common, in handpicked coffee estates to see the pickers at a collection point, ‘Winnowing’ before sending the ripe coffee cherry down to the processing mill. Simple Winnowing involves a loose-weave bamboo tray, where small particles of dirt can fall through and be removed from the coffee batch.
Furthermore the plantation workers skilfully throw the picked product into the air allowing the wind or air current to blow the light leaves and things away from the coffee cherry, which lands back into the tray, because of their weight and density. This defect removal is especially helpful for natural process whole cherry sun drying, where rotting leaf matter may taint the flavour of the beans.
Coffee Process – Entering the Processing Plant
Auger feeders move the recently picked coffee cherries into the processing system. It is important for the recently picked cherries to be processed soon after harvesting to remove the parchment coffee from surrounding fruit pulp. Natural fermentation in the hot and humid conditions must not occur before pulping occurs
Timing of incoming harvested coffee cherries, through the process plant is critical to deliver a quality bean at the end of a lengthy process. Visual finish is also important, and it is the auger feed that delivers the soft ripe coffee cherries into the processor without clipping or squashing the two beans inside each coffee cherry.
Coffee Process – Washing, Cleaning and Pulping
The coffee cherries are washed clean of dirt and clinging plant debris before moving into the pulping equipment. Leaves and twigs also float off leaving only clean coffee cherries to proceed into the mechanical processor. The pulping drum, breaks the outside of the coffee cherry, peeling off a section of the skin and fruit pulp, this allows the two coffee beans to be pressure ejected from the remaining surrounding fruit.
The washing of the cherry before pulping ensures that only the parchment coffee, surrounded with a slimy mucilage, will proceed into the remaining processing system. This care in the processing system maintains and adds another quality finish dimension to the remaining steps of the bean production.
Coffee Process – Fermentation
After pulping the coffee cherry, the two parchment beans, surrounded by a fruity slimy mucilage are transferred by conveyor belt and water to the fermentation tanks. Here the beans are immersed in water with an added enzyme, which accelerates the fermentation break down of the fruity mucilage in a controlled environment and most importantly within managed time frames, so as not to affect the bean.
The treated mucilage can then be easily washed off, leaving a clean finished wet-parchment bean for future drying procedures.
Coffee Process – Parchment Drying
The wet parchment beans are moved in huge bulk lots from the processing mill, to drying pans. These pans are large, flat and generally concrete based, to ensure that no soil moisture travels up into the beans. On small drying pans or where mechanization is not affordable, plantation workers use wooden rakes to spread and turn the wet parchment beans, continually turning them over for an evenly dried outcome.
Larger plantation companies utilise large drying pan areas and use graders and front end loaders to spread the heavy wet beans, to an even depth across the drying pan surface.
Coffee Process – Drying the Beans
After pulping the parchment beans from coffee cherry and washing the slimy mucilage off the exterior of the beans, drying the parchment beans occurs. Two methods are used commonly:
1. Using large gas fired revolving drum dryers
2. Using sun drying when the beans are spread evenly over large drying pans which is highly effective and cost efficient too.
It is important keep any rain or heavy dew off these drying beans, to prevent the onset of fermentation and unwanted flavour taints. The beans are dried down to approximately 11-12% moisture content, which is a globally accepted level. From here the beans proceed to hulling, which removes the parchment coating leaving the green coffee bean ready for the international market.
Coffee Proceess – New Crop Analysis
Before trucking the new crop to port for exportation, careful analysis of the green bean crop is undertaken. Large plantations have in-house analysis and testing facilities to assess the quality of their product. Smaller plantation owners rely on analysis centres close to port, to undertake this necessary check on their behalf.
The quality control analysis is critical before the exportation of any new crop can occur, expert staff check for characteristics, including size grading, appearance, colour, moisture content levels, defect count, quality of processing and visual characteristic due to plantation growth and processing production. This all occurs before the all important cupping analysis is undertaken.
Coffee Process – Cupping and Sensory Analysis
The most important analytical factor of the new crop coffee, and one that is the most important to the end consumer, is the outcome of the coffee cupping sampling. Small batch sample roasting is undertaken, then perfectly ground/milled to the correct particle size.
Gram weight of all samples, are evenly measured, along with consistent hot water volume and temperature. The cupping involves slurping and spitting, where sensory analysis is carefully noted. Characteristics of fragrance/aroma, flavour, strength/intensity, sweetness, bitterness, acidity, body, aftertaste/finish and balance are measured.
These cupping notes are then relayed to the global export market with sample beans so that the coffee traders can present the bean offering to the roasters and the ultimate consumer.