A coffee plant usually starts to produce flowers three to four years after it is planted, and it is from these flowers that the fruits of the plant (commonly known as coffee cherries) appear, with the first useful harvest possible around five years after planting. The cherries ripen around eight months after the emergence of the flower, by changing color from green to red, and it is at this time that they should be harvested. In most coffee-growing countries, there is one major harvest a year; though in countries like Colombia, where there are two flowerings a year, there is a main and secondary crop, the main one April to June and a smaller one in November to December.

In most countries, the coffee crop is picked by hand, a labor-intensive and difficult process, though in places like Brazil, where the landscape is relatively flat and the coffee fields immense, the process has been mechanized. Whether picked by hand or by machine, all coffee is harvested in one of two ways:

Strip Picked: All coffee fruit is removed from the tree, regardless of maturation state. This can either be done by machine or by hand. In the first method, pickers generally place a canvas on the ground. They then grab the branch next to the trunk with their hands and pull outward, knocking all of the fruit onto the ground. After doing this with all branches and trees for the length of the canvas, the pickers then collect the coffee in bags. This process can be facilitated through the use of mechanical strippers.

Mechanical strippers used for coffee fruit harvesting

Selectively Picked: Only the ripe cherries are harvested and they are picked individually by hand. Pickers rotate among the trees every eight to ten days, choosing only the cherries, which are at the peak of ripeness. It usually takes two to four years after planting for a coffee plant to produce coffee beans that are ripe enough to harvest. The plant eventually grows small white blossoms that drop and are replaced by green berries. These green berries will become a deep red color as they ripen. It takes about 9 months for the green cherries to reach their deepest red color. Because this kind of harvest is labor-intensive, and thus more costly, it is used primarily to harvest the finer arabica beans.

Workers sorting and pulping coffee beans in Guatemala

The laborers who pick coffee by hand receive payment by the basketful. As of 2003, payment per basket is between US$2.00 to $10 with the overwhelming majority of the laborers receiving payment at the lower end. An experienced coffee picker can collect up to six or seven baskets a day. Depending on the grower, coffee pickers are sometimes specifically instructed to not pick green coffee berries since the seeds in the berries are not fully formed or mature. This discernment typically only occurs with growers who harvest for higher end/specialty coffee where the pickers are paid better for their labor. Lots comprising unripe coffee fruit are often used to produce cheaper mass consumer coffee beans, which are characterized by a displeasingly bitter/astringent flavor and a sharp odor. Red berries, with their higher aromatic oil and lower organic acid content, are more fragrant, smooth, and mellow. As such, coffee picking is one of the most important stages in coffee production.

Processing

Wet process

Coffee processing aquapulp

In the wet process, the fruit covering the seeds/beans is removed before they are dried. Coffee processed by the wet method is called wet processed or washed coffee. The wet method requires the use of specific equipment and substantial quantities of water.

The coffee cherries are sorted by immersion in water. Bad or unripe fruit will float and the good ripe fruit will sink. The skin of the cherry and some of the pulp is removed by pressing the fruit by machine in water through a screen. The bean will still have a significant amount of the pulp clinging to it that needs to be removed. This is done either by the classic ferment-and-wash method or a newer procedure variously called machine-assisted wet processing, aquapulping or mechanical demucilaging:

Sorting coffee in water

In the ferment-and-wash method of wet processing, the remainder of the pulp is removed by breaking down the cellulose by fermenting the beans with microbes and then washing them with large amounts of water. Fermentation can be done with extra water or, in "Dry Fermentation", in the fruit's own juices only.

The fermentation process has to be carefully monitored to ensure that the coffee doesn't acquire undesirable, sour flavors. For most coffees, mucilage removal through fermentation takes between 24 and 36 hours, depending on the temperature, thickness of the mucilage layer and concentration of the enzymes. The end of the fermentation is assessed by feel, as the parchment surrounding the beans loses its slimy texture and acquires a rougher "pebbly" feel. When the fermentation is complete, the coffee is thoroughly washed with clean water in tanks or in special washing machines.

In machine-assisted wet processing, fermentation is not used to separate the bean from the remainder of the pulp; rather, this is done through mechanical scrubbing. This process can cut down on water use and pollution since ferment and wash water stinks. In addition, removing mucilage by machine is easier and more predictable than removing it by fermenting and washing. However, by eliminating the fermentation step and prematurely separating fruit and bean, mechanical demucilaging can remove an important tool that mill operators have of influencing coffee flavor. Furthermore, the ecological criticism of the ferment-and-wash method increasingly has become moot, since a combination of low-water equipment plus settling tanks allows conscientious mill operators to carry out fermentation with limited pollution.

Any wet processing of coffee produces coffee wastewater which can be a pollutant. Ecologically sensitive farms reprocess the wastewater along with the shell and mucilage as compost to be used in soil fertilization programs. The amount of water used in processing can vary, but most often is used in a 1 to 1 ratio.

After the pulp has been removed what is left is the bean surrounded by two additional layers, the silver skin and the parchment. The beans must be dried to a water content of about 10% before they are stable. Coffee beans can be dried in the sun or by machine but in most cases it is dried in the sun to 12-13% moisture and brought down to 10% by machine. Drying entirely by machine is normally only done where space is at a premium or the humidity is too high for the beans to dry before mildewing.

Coffee drying in the sun. Dolka Plantation Costa Rica

When dried in the sun coffee is most often spread out in rows on large patios where it needs to be raked every six hours to promote even drying and prevent the growth of mildew. Some coffee is dried on large raised tables where the coffee is turned by hand. Drying coffee this way has the advantage of allowing air to