[Continued from Part 1]
Treatment of the Berries
The berries are treated as as follows. General references are the National Coffee Association and Wikipedia.)
- Picking: There are three methods of harvesting the berries.
- Selective picking: The berries are harvested by hand when they are at the peak of ripeness. Since the berries don't mature at the same time (you can see this in the pictures above), this means that several passes must made through the trees to get all the berries as they ripen.
- Stripping by hand: All the berries are picked at once by hand; the berries that are under- or over-ripe are discarded. This method is cost-effective in Brazil where the berries ripen uniformly; by carefully choosing the harvest time, about 75 percent of the berries can be harvested when dead ripe. While it might seem wasteful to discard the unripe berries, this is justified by the lower cost of selective picking.
- Mechanical picking: This is the same as stripping by hand except that the beans are picked by machine rather than by hand.
- Processing: There are two steps. (There are various methods that differ in important ways; rather than attempting to catalog them all, the focus here is only on the gist of the process.)
- Cleaning: The mixture that is harvested is cleaned to obtain the ripe berries and to discard the under-and over-ripe berries as well as the twigs and other debris that are present. (Those of you who have heard me describe by career as a clodpuller will immediately understand this processing.) One preliminary method is to throw the mixture into the air and let the breeze winnow it; see picture.
- Removing the pulp and the other layers around the seed (see the two picture of these layers): This is done by various methods that I will not go into.
- Drying: The moisture content of the beans needs to be reduced from 60 percent to about 11 percent. The traditional method of drying is to place the beans on a table so that air can get at them from all directions. Another method is to place them on a concrete surface in the sun and periodically rake them; this is pictured below. The dried beans that have not yet been roasted are called green beans.
- Sorting: The green beans are typically sorted by color to remove defective beans. This can be done by hand or machine.
- Roasting: The green beans are roasted at a temperature above 393 degrees F. Roasting causes water loss and chemical changes that give coffee its characteristic taste and aroma [Pendergrast, p. 387]. There are heated disputes over the merits of the different philosophies of exactly how roasting should be conducted.
- Grading: The roasted beans are sorted according to color, which indicates the coffee's degree of flavor development.
- Decaffeination (optional): Various chemical means are used to remove the caffeine, if desired. The caffeine is sold to the pharmaceutical and soft drink industries [Pendergrast, pp. 274-75, Weinberg and Bealer, p. 227]. In fact, some producing countries extract the caffeine from poor quality beans, throw the processed beans away, and export the caffeine to industrialized countries [Weinberg & Bealer, p. 232].
The rest of the story of producing a cup of coffee is familiar to readers and is skipped. I will just note that the trick to brewing a cup of coffee is, as Wikipedia states, that "... the beans be ground and then mixed with hot water long enough to allow the flavor to emerge but not so long as to draw out bitter compounds." Many different methods of varying effectiveness are in use, but I will not survey them.
[Continued in Part 3]
