All About Coffee Part 48

The coffee cherry ripens about six to seven months after the tree has flowered, or blossomed; and becomes a deep purplish-crimson color. It is then ready for picking. The ripening season varies throughout the world, according to climate and alt.i.tude. In the state of So Paulo, Brazil, the harvesting season lasts from May to September; while in Java, where three crops are produced annually, harvesting is almost a continuous process throughout the year. In Colombia the harvesting seasons are March and April, and November and December. In Guatemala the crops are gathered from October through December; in Venezuela, from November through March. In Mexico the coffee is harvested from November to January; in Haiti the harvest extends from November to March; in Arabia, from September to March; in Abyssinia, from September through November.

In Uganda, Africa, there are two main crops, one ripening in March and the other in September, and picking is carried on during practically every month except December and January. In India the fruit is ready for harvesting from October to January.

[Ill.u.s.tration: TANDEM COFFEE PULPER OF ENGLISH MAKE

Being a combination of a Bon-Accord-Valencia pulper with a Bon-Accord repa.s.sing machine]

_Picking_

The general practise throughout the world has been to hand-pick the fruit; although in some countries the cherries are allowed to become fully ripe on the trees, and to fall to the ground. The introduction of the wet method of preparation, indeed, has made it largely unnecessary to hand-pick crops; and the tendency seems to be away from this practise on the larger plantations. If the berries are gathered promptly after dropping, the beans are not injured, and the cost of harvesting is reduced.

The picking season is a busy time on a large plantation. All hands join in the work--men, women and children; for it must be rushed. Over-ripe berries shrink and dry up. The pickers, with baskets slung over their shoulders, walk between the rows, stripping the berries from the trees, using ladders to reach the topmost branches, and sometimes even taking immature fruit in their haste to expedite the work. About thirty pounds is considered a fair day's work under good conditions. As the baskets are filled, they are emptied at a "station" in that particular unit of the plantation; or, in some cases, directly into wagons that keep pace with the pickers. The coffee is freed as much as possible of sticks, leaves, etc., and is then conveyed to the preparation grounds.

A s.p.a.ce of several acres is needed for the various preparation processes on the larger plantations; the plant including concrete-surfaced drying grounds, large fermentation tanks, washing vats, mills, warehouses, stables, and even machine shops. In Mexico this place is known as the _beneficio_.

_Washed and Unwashed Coffee_

Where water is plenty, the ripe coffee cherries are fed by a stream of water into a pulping machine which breaks the outer skins, permitting the pulpy matter enveloping the beans to be loosened and carried away in further washings. It is this wet separation of the sticky pulp from the beans, instead of allowing it to dry on them, to be removed later with the parchment in the hulling operation, that makes the distinction between washed and unwashed coffees. Where water is scarce the coffees are unwashed.

Either method being well done, does washing improve the strength and flavor? Opinions differ. The soil, alt.i.tude, climatic influences, and cultivation methods of a country give its coffee certain distinctive drinking qualities. Washing immensely improves the appearance of the bean; it also reduces curing costs. Generally speaking, washed coffees will always command a premium over coffees dried in the pulp.

[Ill.u.s.tration: Costa Rica Vertical Coffee Washer]

[Ill.u.s.tration: Continuous Working Horizontal Coffee Washer]

Whether coffee is washed or not, it has to be dried; and there is a kind of fermentation that goes on during washing and drying, about which coffee planters have differing ideas, just as tea planters differ over the curing of tea leaves. Careful scientific study is needed to determine how much, if any, effect this fermentation has on the ultimate cup value.

_Preparation by the Dry Method_

The dry method of preparing the berries is not only the older method, but is considered by some operators as providing a distinct advantage over the wet process, since berries of different degrees of ripeness can be handled at the same time. However, the success of this method is dependent largely on the continuance of clear warm weather over quite a length of time, which can not always be counted on.

In this process the berries are spread in a thin layer on open drying grounds, or barbecues, often having cement or brick surfaces. The berries are turned over several times a day in order to permit the sun and wind thoroughly to dry all portions. The sun-drying process lasts about three weeks; and after the first three days of this period, the berries must be protected from dews and rains by covering them with tarpaulins, or by raking them into heaps under cover. If the berries are not spread out, they heat, and the silver skin sticks to the coffee bean, and frequently discolors it. When thoroughly dry, the berries are stored, unless the husks (outer skin and inner parchment) are to be removed at once. Hot air, steam, and other artificial drying methods take the place of natural sun-drying on some plantations.

In the dry method, the husks are removed either by hand (threshing and pounding in a mortar, on the smaller plantations) or by specially constructed machinery, known as hulling machines.

[Ill.u.s.tration: Coban Pulper in Tachira, Venezuela]

_The Wet Method--Pulping_

The wet method of preparation is the more modern form, and is generally practised on the larger plantations that have a sufficient supply of water, and enough money to instal the quite extensive amount of machinery and equipment required. It is generally considered that washing results in a better grade of bean.

In this method the cherries are sometimes thrown into tanks full of water to soak about twenty-four hours, so as to soften the outer skins and underlying pulp to a condition that will make them easily removable by the pulping machine--the idea being to rub away the pulp by friction without crushing the beans.

On the larger plantations, however, the coffee cherries are dumped into large concrete receiving tanks, from which they are carried the same day by streams of running water directly into the hoppers of the pulping machines.

At least two score of different makes of pulping machines are in use in the various coffee-growing countries. Pulpers are made in various sizes, from the small hand-operated machine to the large type driven by power; and in two general styles--cylinder, and disk.

The cylinder pulper, the latest style--suggesting a huge nutmeg-grater--consists of a rotary cylinder surrounded with a copper or bra.s.s cover punched with bulbs. These bulbs differ in shape according to the species, or variety, of coffee to be treated--_arabica_, _liberica_, _robusta_, _canephora_, or what not. The cylinder rotates against a breast with pulping edges set at an angle. The pulping is effected by the rubbing action of the copper cover against the edges, or ribs, of the breast. The cherries are subjected to a rubbing and rolling motion, in the course of which the two parchment-covered beans contained in the majority of the cherries become loosened. The pulp itself is carried by the cover and is discharged through a pulp shoot, while the pulped coffee is delivered through holes on the breast. Cylinder machines vary in capacity from 400 pounds (hand power) to 4,800 pounds (motive power) per hour.

Some cylinder pulpers are double, being equipped with rotary screens or oscillating sieves, that segregate the imperfectly pulped cherries so that they may be put through again. Pulpers are also equipped with attachments that automatically move the imperfectly pulped material over into a repa.s.sing machine for another rubbing. Others have attachments partially to crush the cherries before pulping.

The b.r.e.a.s.t.s in cylinder machines are usually made with removable steel ribs; but in Brazil, Nicaragua, and other countries, where, owing to the short season and scarcity of labor, the planters have to pick, simultaneously, green, ripe, and over-ripe (dry) cherries, rubber b.r.e.a.s.t.s are used.

[Ill.u.s.tration: NIAGARA POWER COFFEE HULLER]

[Ill.u.s.tration: MCKINNON'S GUARDIOLA COFFEE DRIER]

[Ill.u.s.tration: THE SQUIER-GUARDIOLA COFFEE DRIER, WITH DIRECT-FIRE HEATER]

[Ill.u.s.tration: BRITISH AND AMERICAN COFFEE DRIERS--GUARDIOLA SYSTEM

There are numerous makes of coffee driers based upon the original invention of Jose Guardiola of Chocola, Guatemala. In the two ill.u.s.trated above both direct-fire heat and steam heat may be utilized]

The disk pulper (the earliest type, having been in use more than seventy years) is the style most generally used in the Dutch East Indies and in some parts of Mexico. The results are the same as those obtained with the cylindrical pulper. The disk machine is made with one, two, three, or four vertical iron disks, according to the capacity desired.

The disks are covered on both sides with a copper plate of the same shape, and punched with blind punches. The pulping operation takes place between the rubbing action of the blind punches, or bulbs, on the copper plates and the lateral pulping bars fitted to the side cheeks. As in the cylinder pulper, the distance between the surface of the bulbs and the pulping bar may be adjusted to allow of any clearance that may be required, according to the variety of coffee to be treated.

[Ill.u.s.tration: ANOTHER AMERICAN GUARDIOLA DRIER]

Disk pulpers vary in capacity from 1,200 pounds to 14,000 pounds of ripe cherry coffee per hour. They, too, are made in combinations employing cylindrical separators, shaking sieves, and repa.s.sing pulpers, for completing the pulping of all unpulped or partially pulped cherries.

_Fermentation and Washing_

The next step in the process consists in running the pulped cherries into cisterns, or fermentation tanks, filled with water, for the purpose of removing such pulp as was not removed in the pulping machine. The saccharine matter is loosened by fermentation in from twenty-four to thirty-two hours. The ma.s.s is kept stirred up for a short time; and, in general practise, the water is drawn off from above, the light pulp floating at the top being removed at the same time. The same tanks are often used for washing, but a better practise is to have separate tanks.

Some planters permit the pulped coffee to ferment in water. This is called the wet fermentation process. Others drain off the water from the tanks and conduct the fermenting operation in a semi-dry state, called the dry fermentation process.

The coffee bean, when introduced into the fermentation tanks, is enclosed in a parchment sh.e.l.l made slimy by its closely adhering saccharine coat. After fermentation, which not only loosens the remaining pulp but also softens the membranous covering, the beans are given a final washing, either in washing tanks or by being run through mechanical washers. The type of washing machine generally used consists of a cylindrical tub having a vertical spindle fitted with a number of stirrers, or arms, which, in rotating, stir and lift up the parchment coffee. In another type, the cylinder is horizontal; but the operation is similar.

_Drying_

The next step in preparation is drying. The coffee, which is still "in the parchment," but is now known as washed coffee, is spread out thinly on a drying ground, as in the dry method. However, if the weather is unsuitable or can not be depended upon to remain fair for the necessary length of time, there are machines which can be used to dry the coffee satisfactorily. On some plantations, the drying is started in the open and finished by machine. The machines dry the coffee in twenty-four hours, while ten days are required by the sun.

[Ill.u.s.tration: THE SMOUT PEELER AND POLISHER]

The object of the drying machine is to dry the parchment of the coffee so that it may be removed as readily as the skin on a peanut; and this object is achieved in the most approved machines by keeping a hot current of air stirring through the beans. One of the best-liked types, the Guardiola, resembles the cylinder of a coffee-roasting machine. It is made of perforated steel plates in cylinder form, and is carried on a hollow shaft through which the hot air is circulated by a pressure fan.

The beans are rotated in the revolving cylinder; and as the hot air strikes the wet coffee, it creates a steam that pa.s.ses out through the perforations of the cylinder. Within the cylinder are compartments equipped with winged plates, or ribs, that keep the coffee constantly stirred up to facilitate the drying process. Another favorite is the O'Kra.s.sa. It is constructed on the principle just described, but differs in detail of construction from the Guardiola, and is able to dry its contents a few hours quicker. Hot air, steam, and electric heat are all employed in the various makes of coffee driers. A temperature from 65 to 85 centigrade is maintained during the drying process.

[Ill.u.s.tration: O'KRa.s.sA'S COFFEE DRIER COMBINED WITH DIRECT-FIRE HEATER]

When thoroughly dry, the parchment can be crumbled between the fingers, and the bean within is too hard to be dented by finger nail or teeth.

_Hulling, Peeling, and Polishing_