Coffee: From Plantation to Cup

Arabica coffee generally grows between the Tropic of Cancer and the Tropic of Capricorn at altitudes of 2000 to 6000 feet above sea level. It requires a consistent temperature between 68° and 75°F and cannot tolerate frost or excessive heat. It also needs 60 to 80 inches of rainfall annually.

Young coffee plants grow in heavily shaded nurseries for at least six months.

There are many varieties of arabica coffee. Older varieties such as bourbon and typica tend to grow tall.

Some of the newer varieties such as caturra, catimore, and catuai only grow to about one meter tall.

During harvest season, many of the workers live on the farm.

Coffee farms are sometimes remote and not easily accessible.

Coffee trees do not tolerate direct sunlight well. They are frequently grown under shade trees. Banana and guava trees are popular shade tree choices but many other trees are also used.

When a coffee tree is four or five years old it will begin to bear fruit and is old enough to harvest.

The flowering is triggered by rainfall rather than by temperature or daylight. About two weeks after a heavy rain, the tree will blossom.

Because a tree can flower several times during the season, the fruit does not ripen all at once and it is possible to find green cherries and ripe cherries on the same tree and even on the same branch.

Only ripe cherries should be picked, so each tree must be harvested several times.

The pickers must be careful not to damage the buds that have already formed for the next crop.

These cherries are overripe and will produce a lower quality coffee.

Wet Processing

Coffee must be processed immediately after it is picked. The most common method for better coffees is the wet method. Coffees prepared with the wet method are called washed coffees. Modern wet beneficios, or mills, are often built on hillsides to allow gravity to help move the coffee through the mill.

When the coffee arrives at the mill, it is poured into a receiving tank.

Water is added to wash away any sticks or leaves that may be mixed in with the cherries.

Cherries that float are also removed because they are usually empty or contain underdeveloped seeds.

From the receiving tank, the cherries move to the first depulpers which squeeze the seeds out of the fruit.

Smaller or less ripe fruit is taken to the second depulper which uses rotating blades to scrape the fruit off of the seeds.

After depulping, the coffee moves to the fermentation tanks where it is left for 24 to 48 hours. During fermentation the coffee pulp, called mucilage, that coats the beans is broken down by fermentation. Fermentation is complete when the coffee will wash clean in water.

After fermentation, the coffee is moved into canals filled with running water where the mucilage is washed off.

When the coffee is clean, it is taken out of the water.

The wet coffee is spread out on patios to dry in the sun. In areas where there is not enough sun, the coffee might be partially or completely dried in mechanical dryers.

Some farms do not have drying facilities and take their wet coffee to another mill. The coffee is always checked for mustiness when it arrives. Coffee that cannot be processed immediately is kept in a ventilated silo.

Some mills use pre-dryers which condition the coffee so that it has a uniform moisture content when it enters the dryers.

The dryers tumble the coffee for about 8 hours at about 160°F until the coffee has a moisture content of about 12%.

At this point, the coffee still has the parchment covering the beans.

The coffee is called pergamino or parchment coffee until the parchment is removed.

Hulling machines gently rub the parchment off of the green coffee.

The parchment is now called chaff.

Blowers separate the chaff from the coffee by blowing the chaff up while allowing the heavier coffee beans to fall.

The chaff is collected and taken to the dryers where it is burned for fuel.

Mills are often able to fuel their dryers entirely by burning the chaff.

The green coffee is taken to sorting machines. This machine, called an Oliver, has a vibrating top that shakes the coffee beans and sorts them based on their density.

Some mills also use other machines that sort coffee by color or by size.

Any remaining defective beans are removed by hand.

The finished coffee is weighed into 69Kg sacks for shipment.

The coffee is shipped in containers filled with sacks of coffee.

Some ports can handle bulk coffee. Shipments to these areas are made by filling containers directly with beans rather than with bags of beans.

Coffee importers, brokers, and roasters will cup samples of the coffee before they buy. The coffee is roasted in small sample roasters and is immediately prepared and tasted.

Dry Processing

Dry processed coffees are also called natural coffees. The coffee is allowed to dry in the sun inside the cherries for about a month.

It can be difficult to produce natural coffees because it requires continuous sunny weather. There is also the danger of microorganisms growing in the pulp that could affect the coffee quality. In areas with little water, however, dry processing is the only option and a carefully processed natural coffee can be as good as a well prepared washed coffee.

When the cherries are dry, they are put in the hullers to remove both the cherry and the parchment. The coffee is then sorted and prepared for shipment.

Photographs on this page were taken by Renae Wilson during a 1997 trip through El Salvador, Honduras, and Nicaragua.