Before the workers load the coffee cherries into the trailer of the tractor, the foreman registers the coffee sacks, so that later the wages can be paid to the people according to the work done by them.
Once all the sacks have been emptied, the ride leaves for the water canal. After the mechanical harvest, the trailer is directly filled by the harvest machine, and naturally nothing needs to be registered for that.
As the tractor comes to the water canal, Paulo takes over the load; retracting backwards is “a top priority”, since the trailer had tipped over here once.
Then one of the workers unloads the coffee cherries, the flowing water takes the cherries with it in the canal; the force of the outflow must be regulated, so that the water pressure is not too high. A barrier in the water canal holds back the cherries that have sunk i.e. the heavier (ripe and unripe), the lighter (over ripe, dry) and consequently, the ones floating on top that are flowing away with the water.
The Processing – The Washing
('O processamento – a lavagem’)
In the water canal the ripe red and the unripe green, that is the moist and thus the heavy cherries are separated from the dry ones floating on top. The workers lay out both the cherry groups to dry separately after this procedure. To this Paulo explains: “They need varying time periods to dry because of their unequal levels of maturity. If they stay together, the ‘passas’ and 'bóias' or the over ripe cherries would later dry up under the sun.”
Controlling the water supply and the speed of the outflow of the coffee cherries is likewise a priority: “Because a lot can go wrong, especially due to the quantity of water. With too much water coming in, the whole coffee shoots back into the field. This has happened before and that is why I prefer to do it myself,” says Paulo.
At the end of the canal is the area for placing the cherries for drying in the air and under the sun and behind that is the warehouse, the so-called ‘tulha’.
|The Processing –
Dry Processing Method
('O processamento – via seca’)
The original and easier process is the dry processing method, which they have been using in the Fazenda Boa Vista for a long time. It is still even today the preferred processing method applied in Brazil and also in Africa.
The impurities are cleaned, and the coffee cherries separated according to the levels of maturity, are spread out on a huge drying area. They are constantly turned around and between two weeks to a month they are dried under the sun in their shells.
At the end of the canal are several locks, with whose help the workers purposefully fetch the coffee cherries and divide them on the area intended for them. The cherries are shoved with a wooden slider out of the canal and shoveled into the wheelbarrow. The cherries are then spread out on to the ground area.
As a lot of coffee cherries have to be channeled out of the canal all at one time, the whole procedure has to take place quickly. Once the wheel-barrow is full, the colourful load is sent to be distributed, because the next is again on its way.
Migel is the head of the dry plant facility. As the head he is responsible
not only for laying out and turning the coffee cherries correctly, but also
for the maintenance, rules and cleanliness of the entire plant facility. He
lives on the Fazenda and carries out his work with his heart and soul, he
is always there and ready.
Migel and one or two of his colleagues, depending on who has the time, has to keep turning around the laid out dry coffee cherries – the whole day long. This has been done for years with a coffee slider. The ‘waves’ that come because of it must be turned around with the course of the sun; thus the sun’s rays can be optimally used.
In winter it is dry and does not rain much. If however, rain is
announce, Migel will pile the coffee cherries on tracks in the
direction of the slopes, so that the rain water drains away
between the tracks. If it rains hard, then Migel covers the pile
with a plastic tarpaulin.
The dry phase lasts as long as the flesh of the fruit is fully dry: the beans rattle in their shells when shaken. For Paulo this is naturally not the criterion to end the dry phase of the scattering. He measures the water content with an electronic moisture meter – daily, at the end of the phase.
Once the dried cherries have reached water content of 11.5%, Paulo stores the black fruits first in the warehouse, the ‘tulha’. Then later, shortly before the sale Paulo de-husks the coffee cherries with a husking machine, i.e. the shells, parchment membrane and the silver membrane will be removed.
|The Processing –
Wet Processing Method
('O processamento - via úmida')
In addition to the above described dry processing there is another possibility, of processing the coffee after the harvest, the so called wet processing method.
In this method, the coffee farmer washes the freshly harvested cherries first in water to remove the impurities.
Just as in the dry processing, here also the ripe coffee fruits sink, the ‘bojas’ and ‘passas’ swim on the top layer and are separately processed.
The difference is that the ripe cherries remain in water as long as they swell up. Then they are squeezed in a big cylinder with a measured sieve. This way the flesh of the fruit is already detached directly after the harvest.
A short fermentation causes an additional improvement in quality and thus the last part of the flesh of the fruits is also stripped away.
After this last purification the coffee beans are enclosed only with the parchment membrane (‘pergaminho’) as well as the silver membrane lying within it.
|The Processing –
Drying and Turning
('O processamento - a secagem e o revolvimento')
Then begins the process of drying, just like the dry processing method, only without the shells. At a later stage, the parchment membrane will still have to be removed through a second mechanical shelling process.
This is why the procedure for wet processing is more complex and expensive. The resulting coffee is called washed coffee in English, in Brazilian it is called cereja descascado (shelled cherries) or in short “CD”.
It has been generally believed that the most important variables that matter in the determination of the coffee quality, the maturity level and the homogeneity of the coffee cherries vary. For example, because with the wet processing only the ripened fruits are selected, whereas in dry processing, all the coffee cherries are processed irrespective of their maturity level.
A group from the German Technical University Carolo-Wilhelmina in Braunschweig had put this assumption to test and examined the coffee seeds from both methods. The results showed that clearly different metabolic processes had taken place depending on how the coffee seeds were processed. (For example in wet-treated coffee it was proved that there was a bigger share of free amino acids, just like those found in proteins.
In contrast a greater share of glucose, fructose and other substances are found in dry-treated coffee). These variations influence the quality and show that exactly the same coffee seeds can develop several different chemical characteristics depending on how they are processed.
Bigger coffee farmers flip the coffee while drying typically with the help of bigger equipment, and often these are self-constructed. I found a nice example for motorized equipment for flipping the coffee in the bigger Fazenda Diamantina: a specially constructed motorcycle(!) accelerated the process immensely.
To accelerate the process of the drying, the bigger Fazendas work also with circulating air oven. In this process warm wind is directed from a wood fire with a fan in a continuously rotating drum containing coffee, whereby a certain temperature and time period are not exceeded. In this way a larger quantity of coffee can be dried quickly. Coffee planter Paulo Marcio says that he must invest carefully: “The money for the new machines has to be first earned,” he says.
The Coffee Storage and the Husking
('A tulha e o beneficiamento - o descascamento')
The old coffee storage, the ‘tulha’ has not changed for generations. With the recent renovation, Paulo ensured everything would be restored in the old style. After the drying process, Paulo stores the coffee here first with the shells (‘casca’).
The fruits that have been dried with the fruit flesh have attained water content of 11-12% by this time. This is an ideal grade for storage. Shortly before sale, when Paulo believes that the price and time are exactly right, the coffee is husked.
The husking machine is indeed from an earlier time, but it works splendidly – the functional principle remains unchanged even today, merely the mechanics and the power transmission technology have become more modern. There is a delightful clatter and rattle, banging and rocking, jolting and shaking when Paulo gets the machine going. Many parts are made from wood and appear cumbersome.
A worker fills the dried coffee from above into the machine
The coffee passes through several processing steps in the machine. At first a cleansing and selection process takes place: An inwardly tapered conical sieve is moving back and forth in a quick radial rhythm. This causes the lighter ground particles to separate from the heavier ones. Thus broken and ‘foreign’ particles, like for e.g. twigs and small pebbles etc. are shaken out. A very easy mechanical principle, but surprisingly precise and effective.
A mechanical lift with plastic containers transports the coffee on to the top, where at the back of the machine there is an open-sided sieve drum and a rather sharp-edged opening. The dry coffee cherries are pushed inside into the drum, from where it is again pushed outwards with a type of ‘circulating spatula’ through exactly measured sieve holes; this way the shells are stripped away from the beans.
The lighter, crumbly parts of the shells are sucked away by the air current and transported into the open. The coffee beans fall down behind and a further sieving system separates them into different size groups. Then they fall into the waiting sacks of coffee.
All of this works with a rattle, rumble and shake, but despite that surprisingly well; there are practically no broken beans. The removed coffee shells serve later as a valuable natural fertilizer.
After the age of 15, the productivity of the coffee trees starts to decline. They are too big to be reasonably harvested irrespective of whether the harvest is manual or mechanical.
The trunk is too high and the branches too long and they do not bear sufficient fruits; they thus ‘waste’ water and nutrients. They work against the coffee farmers, who quite rigorously prune them.
A good time for pruning is shortly before the flowering. Indeed with this, they lose almost a year of the harvest, but thereafter the trees grow stronger again and in the second year after the trimming, bear more fruits.
This way the coffee farmers keep the coffee trees productive for few years more than earlier. The pruning is done with the help of an oversized pad-saw device, which just as in this example, is pulled by Paulo with a tractor.
For the sides there is another device, which is attached to three of the same saws. Thus it trims row-wise all three sides of a row of trees.
The cropped branches are cut further on the ground and serve as natural fertilizer. The result of the pruning at first looks terrible, but soon after a couple of weeks, the effect of the cropped field is clean and ‘young’.