From the tree to the bag

For us it’s normal to brew, in half-awake, our first coffe in the morning. How much work was previously put into the beans, I would like to outline today. My coffee already tastes much better!

Cultivation

  • Coffee trees need a balanced climate without temperature extremes, without too much sunshine and heat.
  • The cultivation areas are located according to the requirements between the turning circles.
  • Coffee is usually propagated by seeds. They are sown in seedlings.
  • The first two leaves of the seedling appear after 5 to 6 weeks.
  • After 8 months, they are planted in the plantation, depending on the variety at intervals of 1-4 meters.
  • The first yield is only after 3-5 years for 10 – maximum 20 years.
  • The trees are constantly cut in height and freed from weeds, fertilized, transplanted, treated, when the for example have leaf disease and all this in often impassable terrain.
  • A lot of work, because 1 tree produces in 1 year only between 500 g – 1 kg roasted coffee!

Picking

1-2 x a year is harvested for up to 12 weeks, because the fruits on the same shrub need different maturation.
2 coffee crops are distinguished: Stripping and Selectively Picked

  • Stripping: All the coffee cherries of the plant are harvested at the same time.
    • by Machine: on commercial coffee plantations like Brazil, harvesting machines are used. A fast method, which is not very gentle for the trees, and harvest ripe and immature coffee cherries together.
    • By hand: It is waited until most coffee cherries are ripe and then they are stripped of the branches. The still immature cherries are later sorted out to improve the quality.
  • Selectively Picked: the most time-consuming method of picking the coffee, as only the ripe cherries are picked – the immature are still left on the shrub and later picked.

Processing

Now the outer layers of the coffee cherries are removed. There are 3 methods: wet process, dry process or semi-dry process. The climate and the desired taste profile decides aout the best fitting process per coffee. To talk about a better quality comparing the wet to the dry process is only partially correct. From the ecological point of view, the dry process wins!

Wet Process

The coffee cherries come in special water tanks. The bad and immature fruits float on the surface of the water, the ripe coffee cherries sink downwards. The latter are pressed mechanically through a sieve or passed through a roller system in order to remove the fruit from the beans. For the removal of the remaining shell residues there are the two methods ‘ferment-and-wash’ and ‘machine-assisted-wet-processing’:

  • Ferment-and-Wash Method: In fermented tanks the beans are fermented between 6 and 70 hours. There are 2 methods:
    • Wet Fermantation. For this purpose, water is added to the tanks, which are enriched with microbial peptide-electrolytic enzymes. (e.g., in Kenya)
    • Dry Fermentation. The moisture of the remaining pulps is sufficient for fermentation. (e.g., in Guatemala)
  • Machine-assisted wet processing: The remaining pulp is not subjected to fermentation and is removed by machine.

After the pulp is removed, parchment and silver skins remain around the beans. For the beans to become stable, the water content must be brought to 10%. This usually happens with drying under the sun but also by machine.

Dry process

The dry process, unwashed or natural coffee is the oldest method. After cleaning the whole cherries are dried in the sun.

  • Cleaning: Unripe, overripe, spoiled coffee cherries as well as leaves, twigs and soils are sorted out.
  • Drying: The fruits that are spread under the sun are used regularly and need 3-5 weeks until they reach a moisture content of 12 % so as not to break or to spoil.

The dried coffee grinders are stored in silos and are put into the rolling mill in time for further processing.

Semi dry process

The washed coffee cherries are mechanically freed from the pulp. This saves water.

  • Wet Fermentation: To remove the remaining pectin layer, the cherry is subjected to a short fermentation of up to 1 day. The mucus layer is then washed off and the parchment coffee is dried.
  • Pulp Natural: After removing the pulp, the cherries are dried directly. The dried mucus layer is removed by machine.

Milling

The final steps of the coffee processing consist of removing the last layers of the dried peel and last fruit residues, cleaning and sorting.

Hulling

When dry, it is the removal of the brittle parchment skin. In the case of the semi-dry process, it is the removal of the parchment skin and the dried pectin layer, and in the case of the dry process it is the removal of the whole dried fruit husk with the help of machines.

Polishing

This is an optional processing step, which also removes the silver skins. The so-called Chaff during roasting is then omitted.

Cleaning and Sorting
  • Sorting by Size and Density are done by machines that simultaneously remove styles, pebbles, and dirt.
  • Photocells and UV light are used for sorting by colour in order to detect and sort immature, black or fermented beans.
Grading / Classification

Finally, the coffee is divided into grades, chopped and stacked in cool, airy storage halls protected from direct daylight. Then they are traded and reach the roasters.

  • Size: in Africa and India: AA> A> B> C <PB (Peaberry). In Central America: Superior, Primera, Tercera, Caracol and Caracolito. 
  • Altitude: from 1,600 m: SHB (Strictly Hard Bean) / SHG (Strictly High Grown), 1,200 – 1600 m: HB (Hard Bean) 
  • Quality: Determines the percentage of deficient beans. According to the SCAA classification one differentiates:
    • Specialty green coffee beans: less than 6 full defects in 300 g of green coffee.
    • Premium Coffee Grade: less than 9 full defects in 300 g.
    • Exchange Coffee Grade: less than 23 full defects in 300 g.
    • Below Standard Coffee Grade: less than 86 defects in 300 g.
    • Off Grade Coffee: more than 86 defects in 300 g.

Trade, Transport and Storage

  • The price depends on the quality of the raw coffee varieties, the supply and demand as well as the stocks of the production and consumption countries. The main species of Arabica and Robusta are traded on the international coffee exchanges in New York and London.
  • 80% of the coffee is shipped as loose bulk goods in containers into the import countries.
  • High-quality green coffee with low harvest volume is still shipped in bags (in the container). From South America to Hamburg or Bremen it takes about 2-3 weeks.
  • Having arrived at the port, stockholders are picking specimens to proof quality deviations or register damage.
  • The coffee beans are either poured from the containers or bags directly into silos or stored in sacks stacked in pallets on storage pallets.
  • Here is an illustration of the German Coffeeshop >>
  • Before the raw coffee arrives at the roaster, there may be many intermediate steps in services. Roasters, which focus on Direct Trade, try to minimize this. Here is a good overview >>

Roasting

Since raw coffee tastes more like peas, the beans are roasted. This gives the coffee its specific colour, taste and flavour. During this roasting, the beans will lose 60 % volume but at the same time 20 % weight. The variety, origin and quality of the raw coffee beans, as well as the roasting time and temperature, determine the result. The longer roasted at low temperature, the higher the roasted coffee quality, since more incompatible chlorogenic acid is degraded and more aromas are built up.

The roasting process can be divided into different phases by means of sensory characteristics of the beans. The appearance and the volume of the beans plays an important role. The clearest signal, however, is the noise of the first or second crack of the beans. The roaster can recognize the aromas, acidity, taste and body the coffee will have in the cup later, and so creating the desired coffee. Call it a science!

Bright roasts result in a rather sour, but less bitter taste, while darker roasts are slightly sweet but bitter. Depending on the type, quality and desired result, the roaster decides on the degree of roasting. Here is a nice overview >>

In general, one distinguishes between industrial hot-air roasting and traditional drum-roasting. In the linked article >> both methods are compared.

If you would like to take a look at my home roasting experiment in the oven, please click here >>

If you prefer to buy your coffee at the Roaster of Trust, here is a roaster overview for Germany >>

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