From the coffee bean to the cup
The coffee plant
The coffee plant belongs to the family of the Rubiaceae, genus Coffea to which belongs various species, among which those of particular importance are the Arabic and the Canefora, better known as Robust. Between the two species the most widespread is the Arabic variety, so much so that three-quarters of the world’s production comes from his cultivation. It is able to produce a beverage that is aromatic, less bitter and less astringent than the Robust quality. The coffee plant produces white flowers with a strong fragrance and has a very short blooming period. From this flower the drupe originates, a fleshy fruit, very similar to a cherry. The drupe has a thick and glossy skin, which is initially green, then bright red in colour at complete maturation.
The flowering of the coffee plant is closely linked to the phenomenon of the rains; in fact, this process takes place as many times as there have been precipitations in the arc of the year. The drupe inside contains two seeds of an elongated oval shape facing each other. The seed of the Arabic variety of colour green has a groove in the shape of an “S”, while that of the Robust variety is more rounded with the furrow that is almost straight and is a pale green, with grey shading. The two seeds are covered with a thick film is a whitish colour called parchment, which has a protective function, while the underlying layer shows us a second film of silver colour, perfectly adherent to the seed.
HOW THE FRUIT IS COLLECTED
There are two ways in which the harvest is carried out: stripping and picking. The first method is to tear off all the fruit from a small twig by passing it between one’s fingers. This implies an inferior quality of the harvest. Picking is, instead, more expensive, as it is done by hand by collecting only the fruit that is cherry red and ripe. We thus obtain from it a high-quality end product.
HOW THE SEED IS EXTRACTED FROM THE FRUIT
After collecting, the seed is extracted from the fruit with dry treatment or with wet treatment. If the collection has been made by stripping, first one must separate the fruit from the leaves, pieces of wood and the random stones.
Then one proceeds with the dry-processing: the beans are dried in the sun for several days and, when the skin and pulp are completely dry, they are passed through a particular machine, which breaks the peel, pulp and parchment, freeing the beans; they are separated and classified according to type and size (“sieve”). The dry treatment gives rise to natural coffees, also called “not washed”. More long and complicated is the wet treatment. To practice this activity, it is necessary to have performed the manual harvest with the picking method that ensures greater uniformity of size and the ripening of the fruits and sufficient softness of the flesh. In fact, as soon as the cherries are picked, they are introduced into specific machines that liberate the seed contained in the parchment. The phase of fermentation follows the release of the fruit pulp, which sets out the immersion of the beans in large water tanks, for two or three days. This treatment, in addition to eliminating the residual pulp, develops in the bean a series of chemical reactions that enhance the aromatic and taste qualities.
After fermentation, the beans in parchment are sieved through a further washing with which the grains that are not perfectly ripe rise to the surface, facilitating the selection. Then the drying phase begins which, if carried out in the sun, improves the characteristics of the washed coffee. Only after drying does one proceed to the elimination of the parchment. The more time and energy that is spent in the wet process is compensated by an excellent quality of the product and a greater consistency of the batches and homogeneity of the beans.
THE ROASTING PROCESS
The next step is that of the roasting process that releases the coffee the aroma, flavour and colour, which are all its own.
It consists in bringing the coffee bean to the drum temperature ranging from 200 to 230 degrees, using special equipment that is basically of two types:
• traditional machines with rotating drum at discontinuous cycle in which the coffee is gradually heated by hot air, for a time varying between 15 and 25 minutes, these are currently the most suitable for coffee roasting destined for espresso;
• machines with fluidised-bed, at continuous cycle, in which one creates a vortex of warm air that keeps the beans in suspension for a minute or slightly longer. The process becomes more economical (more production per unit of time and less weight loss) but, given the speed, does not allow the aromas to form adequately.
At the precise moment desired, the roasted coffee is poured into a cooling drum for the necessary temperature reduction to be obtained, for the coffee that is intended for espresso, exclusively with fresh air. 5 The secret for a perfect aroma. In the process of roasting, the coffee bean undergoes a series of fundamental chemical changes that will characterise the future beverage. The most important in terms of quantity are the caramel and the carbon dioxide, while in the aromatic aspect, therefore qualitative, the primary role is played by over one thousand volatile molecules of different form.
The same mixture can produce espresso with different tastes and aromas, depending on the methods, length and degree of roasting. In fact, with the temperature not only does the amount of aromas vary, but also the relationship between the bitter and sour taste: with the change of the times and temperature one can increase and decrease the bitter/sour ratios.
DECANTATION AND PACKAGING
After the roasting process that makes the coffee beans take on a dark brown colour, the coffee must be preserved in special rigorously hygienic maxi-containers at a temperature of not less than 10 degrees. The procedure is necessary to preserve the “taste and freshness” and to avoid the freezing of the natural oils and fats that would prevent a correct execution of the espresso.
At this point the coffee, once it is packaged, is ready to be consumed.