We all might drink coffee every day. But do we think about how our coffee is harvested and how it is processed? If not then today we will discuss how harvesting and processing of coffee beans are done.
For new experience and great experiences, one must know how the harvesting of the beans are done and which type is best suited and how the beans are processed.
When it comes to harvesting and processing coffee beans many of the stages do affect the taste of our coffee beans. Especially the origin of the coffee should be considered.
What is Harvesting?
First, we should understand what harvesting means. Harvesting is the process where the ripened crops are gathered from the field. It means when the crops get mature then they are cut off from the field of the particular tree they are grown on.
It takes two to four years after planting the coffee plant to produce the full ripen beans, ready for harvesting. The plant first grows the small white blossoms that are replaced by the green cherries of the coffee.
The color changes to deep red as they ripen. It takes the 9th month for the green cherry to become the deep red ripe cherry. When unripened coffee fruits have involved the harvesting, the characteristic is a little displeasing, bitter in flavor, and has a sharp odor.
Ripen red cherries have higher aromatic oil and their lower content of organic acid, they are more fragrant and smooth. When the unripened coffee fruit is involved in the production it makes the product cheaper. When the production involves only ripen cherries it increases the price of the product.
In the case of coffee, they are harvested whether it is by hand or by machine.
Each mature cherry is picked up by hands, individually by the experienced expert coffee pickers. The pickers take round among the trees every week, only choosing the cherries which are at the peak of their ripeness.
Thus, this process is more costly. It requires labor-intensive work. This process results in providing high-quality and expensive coffee. This process is used to harvest the fine Arabica beans.
The stripping process is the process where all the coffee fruit or cherries are removed from the trees regardless of whether they are mature or not.
They place the canvas on the ground and they grab the branch near the trunk with their hand and pull out, this will in return will pull down all the fruits on the ground. The same process is repeated with the other branches and trees.
In this process, both ripened and unripened cherries are involved in harvesting which in return will give not so high quality as this one doesn’t involve many efforts as it was involved in the picking process.
The mechanized process is the same as the striping process but this process is done with the help of machines. They use mechanical stripers to make the process easy. With the help of the machines, the branches are shaken so that the cherries fell on the ground and can be gathered for further process.
This is the easiest process of harvesting. The process involves both ripen and unripe cherries in harvesting, which doesn’t provide high quality.
What is Processing?
Processing of the coffee beans means removing the outer layers. In this stage, the pulp, the parchment skin, the silver skin, and the mucilage layer are removed.
The processing plays an important role in flavoring the coffee. The honey processed will give it a sweet flavor but the host process will give it a strong flavor.
1. Wet Process
In the wet process, the covering of the seed is removed before it gets dried. Coffee processed by this method is known as wet-processed coffee or washed coffee.
This process needs specific equipment and large quantities of water. Firstly, the cherries are sorted by immersion in water. The bad one or the unripe one will float while the good and ripen will sink. Now the skin has to be removed.
The skin of the cherry is removed by pressing it with the machine in water through a screen. If after this any of the pulp is clinging needs to be removed. The removal of extra pulp is done by the ferment and wash method.
A machine-assisted wet processing or aqua-pulping or mechanical demucilaging method is a newer procedure whereas ferment as wash method is a classic method
Ferment and Wash Method
In this method, the remaining pulp is removed by breaking down the cellulose by fermenting the beans with microbes and washing them with a large amount of water. The fermentation process needs to be carried out carefully to make sure that coffee does not acquire any undesirable or bitter flavors.
In most coffee, the mucilage layer is removed with the help of fermentation. It takes 8 to 36 hours to remove the layer depending on the temperature, thickness, and concentration of the enzyme. At the end of the fermentation, you have to assess it by feel.
The parchment of the bean is lost making it of slimmer texture with a rough pebble feel. When the fermentation process is complete the coffee is washed with clean water. It either gets washed in the tank or a special washing machine.
Machine-Assisted Wet Process
This process is used to remove the remaining pulp with mechanical scrubbing. This process helps in cutting down the use of water and pollution, as the water of ferment and wash methods stings.
Removing the Mucilage layer with the help of the machine is far easier and more predictable than removing it with the ferment and wash process.
- By eliminating the fermentation step and using mechanical demucilaging can remove an important part from the coffee which helps in influencing the flavor of the coffee.
- The mill operators use low water equipment tanks to carry out fermentation with limited pollution.
- When we use a machine-assisted process or semi wash the chances are there that the beans will get chipped or damaged. The beans are grown at a lower altitude when damaged, in return will have some porous feature.
- During the wet process of coffee, wastewater is produced which can be a pollutant. Ecological sensitive farms use that wastewater with the shell and mucilage as a compost which is used as a soil fertilizer.
After the removal of the pulp, the bean is surrounded by two layers: the silver skin layer and the parchment layer. The beans need to be dried at about 10% for being stable.
The beans can be dried by sun or by machines but in most cases, it is sun-dried which to brings down 12% to 13% of moisture by the sun or 10% by machine. The machine drying process is used in places where the weather humidity is too high for the beans.
When the beans are sun-dried they spread in a row where it needs to be laid every 6 hours so that it promotes drying without the growth of mildew. Some coffees are dried on a large-scale table, where the coffee is turned by the hands.
Drying coffee beans on a large raised table has the advantage that the air is circulated better around beans and allows more even drying. This increases the cost of coffee and labor.
After drying the parchment skin or pergamino is thoroughly dried and is prepared for removal.
2. Dry Process
The dry process is the natural process or the process where there is no need to wash coffee, this is the oldest method for processing coffee. After the harvesting is done the cherries are first clean and then placed in the sun to dry on the table or in layers.
The harvested cherries are first sorted and then cleaned. They separate the unripe, overripe, and damaged cherries. Then they remove dirt, soil, twigs, and leaves.
This is done by the method known as winnowing which means two separate the lighter and the heavier material with the help of a tool known as a winnowing fork or shovel.
The unwanted cherries and other foreign particles are, picked out from the top of the sieve. The ripe cherries are separated by the flotation by washing them in the channels flowing near to the drying area.
The drying part is the most important stage of the process because it affects the quality of the green coffee.
If the coffee gets over-dried it will become brittle and during the further process, beans may get broken which will be considered as a defect. If the coffee is not dried sufficiently this will lead to Detroiration which is caused by the attack of fungi and bacteria.
Cherries spread out in the sun. they are spread on a block of large concrete or brick patios or raised to waist height on trestles for drying purposes. The cherries are raked or turned by hand to ensure even drying and to prevent mildew.
It takes almost four weeks to dry out the cherries at optimum weather content. Sometimes we use machines to speed up the drying process after the coffee is pre-dried in the sun for some days.
When the cherries are dried properly they are stored in bulk quantity in special silos ( silos- are the pits or the tall towers in the farmer’s field used to store grains). Then these beans are sold for further processes of milling, sorting, cleaning, roasting, grading, and at last bagging.
This process is used for about 90% of Arabica beans produce in Brazil, Ethiopia, Haiti, and Paraguay, as well as some Arabica, is produced in India and Ecuador with this method. Almost all the robusta beans in any part of the world are processed by this method.
But this method cannot be used in very rainy seasons or the region where the humidity is high or it rains frequently during harvesting.
3. Semi-Dry Process or Wet – Hulled
The semi-dry process is also known as a semi-washed or wet-hulled or pulped natural process. In Indonesia, it is known as “Giling Basah” which means “wet grinding”. This process helps in the reduction of acidity and increases the body.
This process is a hybrid process which is used by small scale farmer in Sumatra, Sulawesi, Flores, and Papua. During this process, farmers remove the outer skin from the cherries mechanically.
For this, they use pulping machines which are locally built. The coffee beans which still have a mucilage layer are stored for a day.
The twisted part about the semi-wash process method is that bacteria is always around. The fermentation can start immediately as the coffees are honey dry with the remaining sugar layer which offers feeding for bacteria.
The drying must be done carefully under supervision because this method is crucial to the success of this processing. The beans must constantly move during drying to prevent any mode of fungal infection.
The processor needs to rake beans two to three times per hour to ensure safe drying of the green coffee beans.
Once the beans are dried sufficiently with the moisture content needed they are drily milling to remove the parchment layer and sent off for roasting and selling globally
Milling – The Last Stage of Processing Coffee Beans
The process of removing the dry skin from the coffee beans and the remaining residue followed by cleaning and sorting them is the final process of coffee processing. These steps are also known as dry milling. The steps that are involved are collectively known as wet milling.
1. Hulling – The Removal of Layers
Hulling is the first step involved in dry milling which is the removal of whatever is left on the beans. This part is done with the help of the machine. The machines are simple stone machines to sophisticated machines that gently whack the coffee.
Anything that is leftover such as crumbly parchment skin left after wet processing, the parchment skin, dried Mucilage of semi-dry process, or any fruit covering of the dried process coffee is removed.
Note: There is an optional process after hulling that is known as polishing in which any silver skin that remains on the bean after hulling is removed with the help of a polishing machine. This is done to make coffee beans appear better and eliminates any by-products of roasting known as chaff.
2. Cleaning – The removal of Foreign Particles
The coffee is passed through several machines to get cleaned. The coffee beans are accompanied by foreign products such as sticks, rocks, nails, and debris that may get mixed during drying.
The beans are blown into the air and separated such as the beans which fall into the closest bin are the heaviest and the biggest, the lightest beans plus foreign particles are blown in the farthest bin
3. Sorting – Grading the Beans
The beans that are collected after they are blown into the air are put into a gravity separator which shakes the sized beans on a tilted table so that they get separated such as the heaviest, high density, and the best vibrated on the one side and the lightest one on the other side.
After this, the beans are sorted based on color, density, and size. This is known as color sorting. It separates defective Beans from the sound beans. This is one of the tricky stages and it’s the most important step. To get the most high-quality coffee color sorting is done in the simplest way that is by hands.
The workers pick up the discolored or defective beans from the sound beans and separate them. The best quality coffee is the one that is cleaned by hand, the most high-quality coffee color is sorted by hand twice or even thrice which means they hand clean more than once.
The special coffees are sorted in this way and this hand cleaned or sort is usually known as European preparation. Color sorting can also be done with the help of the machine.
The streams of beans are for rapidly flow through a sensor that is set according to the parameter and identifies the defective bean by their color. With the help of a tiny decisive puff of compressed air, they kicked out the defective beans from the sound beans as soon as it detects something odd or irregular.
However, these machines are not available widely for two reasons.
- The investment in installing and maintaining these delicate machines is difficult.
- Sorting by hands needs much work which in return gives more employment to small rural communities that stays around the mills.
These machines are essential in the region where there are high standards of living and high salaries demanded.
After this, the coffee beans are separated considering the various criteria such as the size of the bean, where they are grown, at what altitude they were grown, how they were prepared, and how they were picked.
Some coffees may also be graded but the number of imperfections per sample such as a broken bean per sample or unripened beans per sample etc. To get the finest coffee the origin of the beans is really important.
The growers that grow premium quality coffee impose the level of quality in the grading criteria as this helps the coffee to have a higher price and they are recognized with consistent quality.
4. Storage – Storing the Green Beans
The green beans are stored in jute bags or woven poly bags for transportation. Green coffee beans are usable for several years. But they should be stored in a more vulnerable way. Jute bags are porous and expose the coffee to the elements they are surrounded by.
Coffee that is not stored carefully or poorly stored may develop burlap taste which is also known as bagginess This kind of storage may fade the quality of the coffee.
But nowadays special coffee markets have begun to enhance their storage methods. They put gas barrier liners into the jute bags to preserve the quality of the green coffee.
The green coffee is stored in vacuum packs. This will lead to reducing the ability to interact with oxygen or any atmospheric content. All these make storage more expensive.
Roasting is not considered as a part of processing but almost all of the coffee throughout the world is sold in roasted form. They are generally roasted in one of the 4 degrees such as light, medium, medium-dark or dark.
Consumers may buy unroasted beans and roast them at home. It’s a personal choice. Green coffee beans can be used to prepare an infusion or ingested as a ground powder. Green coffee bean’s relevance is limited in the global coffee market.
Where the coffee beans are grown?
Coffee beans are grown near the equator such as 30 degrees to the south and 30 degrees to the north of the equator.
coffee is grown in large amounts in Central America, Brazil, the Caribbean, India, Yemen, Indonesia, Madagascar, East Africa, West Africa, Vietnam.
In which season coffee beans are harvested?
At the North of the equator, they are grown in the winter season and at the south of the equator, they are grown in the summer season.
Is coffee fruit or vegetable?
Coffee, when grows on the coffee plant is known as Coffee Cherries. This means that coffee is a fruit which is also known as Peaberry because it has the shape which resembles a pea
As a coffee drinker, one must know how harvesting and processing of coffee beans are done. Knowing about different ways and method is a must to discover your taste.
If you like a strong flavor then you go for beans that are processed using a washed method. If you want to go for a sweet taste then you can go for beans that are honey processed. If you want something in the middle then you should go to a semi-hulled process coffee beans.