Coffee plant ranks among the fruit trees. Its origin is in Ethiopia, but it spread from here to many other countries of subtropical and tropical belt. Coffee plant can be found either in the form of a bush or a tree growing up to 15 meters. Coffee grows best in acidic soil, its seeds grow about one month and before the farmer gets the first harvest it usually takes another 3-4 years. The fruit of the coffee plant is red to burgundy colour coffee cherry, ripening for twelve to fourteen months. In it there are two grains placed flat side to each other, wrapped in peel parchment. Since the ripening of the coffee cherries, there awaits a long journey before beans will come to coffee beverage.
Coffee plants can be divided into two basic types – Arabica and Robusta.
Arabica coffee fruit is called Caffea arabica, it grows best in South America or Africa. Arabica grows at higher altitudes, at 1000-2000 meters above sea level. Because it is more demanding in cultivation and harvesting it is also a higher price. Arabica with its rich taste and pleasant aroma profile is very popular and contributes about 75% on the total coffee production.
Caffey canephora coffee or Robusta is doing better at lower altitudes at around 700 m above sea level and therefore it is much less demanding in cultivation. Robusta is compared to Arabica of taste flatter, characterized by full bitter, earthy flavour as well as of higher caffeine content.
The higher altitude coffee grows at and the longer it ripens, the better it is, because the sugars and other substances have sufficient time to absorb into grains from the husk of coffee cherries. After their ripening coffee cherries must be harvested and processed in time. This process can take place in three different ways. The quickest and least friendly method of collection is a machine one. A little friendlier is called stripping (teasing) when comber grasps the whole branch and pulls all the coffee cherries. Craftiest, but the most gentle is hand gathering, where coffee cherries are picked individually. This way no unripe or overripe fruits are harvested, which assures high quality of the resulting taste.
After the harvest of cherries it is necessary to start processing the fruit relatively quickly – ideally within 12 hours of being picked. There are three basic ways in which the coffee cherries are processed.
The first is called the wet method. At the beginning of this process beans are husked from coffee cherries. This is done by special machines from which the beans go into cylinders, where they are washed with water and so firstly the selection of beans takes place and also they get rid of pulp and impurities. The bean then still has its silvery membrane, parchment skin and pulp residues. Than beans travel from cylinders through to water tanks where they ferment. During the fermentation they get rid of residual pulp and a slimy layer on the surface. After the fermentation the beans are dried for twelve to fifteen days. After the drying the beans relieve the parchment skin and are finally polished, wherein there is a partial removal of the silvery membrane which residues are completely separated at roasting. The final taste of coffee prepared by the wet process is clear, clean and coffee has stronger acidity.
The second method of processing of coffee is called the dry method. Coffee cherries are freed from dirt, grit, unripe fruits, etc. first. Then, they are spread in a thin layer for about a month and dried in the sun. It is necessary to turn and rake the beans often. Shrunken residues of the cherries are removed along with a parchment skin and silvery membrane before transport to consumers. This method is economically less demanding than washing of coffee, however its disadvantage is the longer drying time and a larger number of defect beans. When processing coffee beans the dry method they remain longer in contact with the pulp, which allows the transition of sugars from pulp in the bean. The taste of coffee is then fuller; coffee has a stronger body, lower acidity and sweet aftertaste.
The third way of processing coffee cherries is called the semi–washed method and it combines the two methods described above. At this technique of processing the ripe fruit are first stripped of the upper fleshy husks in traditional peeling machine, and then they are stored for about one day. Then the beans are washed and the residual pulp removed. Then the beans are dried to moisture content of about 30%. Peeling of parchment skins takes place in the semi-wet conditions.
An important aspect that affects resulting taste of coffee is the roasting. There are different degrees of roasting, each of which highlights other ingredient of coffee. The optimal degree of roasting should be selected with regard to the specific characteristics of each coffee, and also the way coffee will be prepared.
Light – at light roasting flavour potential of coffee does not fully develop, bean is bright cinnamon colour.
Medium light – flavour of medium-light roasted coffee is considerably acidic, bean is light brown.
Medium – the taste is fuller, but acidity is still prevalent, bean is medium brown colour.
Medium dark – at medium dark degree of roasting acidity is slowly suppressed and flavour comes to its fullness, bean has and deep brown colour, oily spots appear on the surface.
Dark – dark roasting degree suppresses subtle flavour nuances, bean is dark brown or black with larger oily stains.
Very dark – very dark at roasting, the coffee flavour becomes flat, bean is completely black, its surface is covered with oil.
More information on the varieties of coffee, its cultivation, processing, trading and roasting can be found on the website www.kavarnik.cz