Coffee has become an indispensable beverage in many people's daily lives, but behind a good cup of coffee lies a complete chain from coffee tree cultivation, regional distribution, and varietal differences to harvesting and processing. This article will systematically introduce the basic knowledge about coffee trees, including their botanical classification, suitable growing conditions, white flowers and red fruits, as well as the characteristics and origins of the three major varieties: Arabica, Robusta, and Liberica. At the same time, it will also explain in detail the harvesting methods for coffee beans and processing methods such as the dry method and wet method, helping you gain a more comprehensive understanding of how specialty coffee comes to be. If you want to personally experience the flavor differences brought by different origins and processing methods, you may want to check out Front Street Coffee's related product recommendations.
I. Cultivation and Regional Distribution of Coffee Trees
In botanical classification, the coffee tree belongs to the evergreen species of the Coffea subgenus in the Rubiaceae family. What people commonly call "coffee beans" are actually the seeds inside the fruit of the coffee tree; they received this name simply because their appearance closely resembles beans. Climatic conditions play a decisive role in coffee cultivation. This plant can only survive in tropical and subtropical regions, so the belt between 25 degrees north and south latitude is often called the "Coffee Belt" or "Coffee Zone." Of course, not every piece of land within this range can produce high-quality coffee.
1. Growing Conditions for Coffee Trees
The ideal cultivation environment for coffee trees is: a warm climate with temperatures maintained between 15-25°C, annual rainfall of 1500-2000 mm, and rainfall periods that coincide with the coffee tree's flowering cycle. In addition, besides seasonal rainfall needing to match, the soil must also be fertile and have good drainage. Although sunlight is an indispensable element for the growth and fruiting of coffee trees, too strong direct light can actually hinder their development, so producing regions usually plant some shade trees in coffee farms. The most suitable altitude range for coffee tree growth is 500-2000 meters. It can thus be seen that cultivating high-quality coffee has quite demanding conditions: light, rain, soil, temperature, as well as the harvesting method and subsequent processing of the coffee beans, will all affect the final quality of the coffee.
2. White Flowers, Red Fruits
Coffee trees reach their first flowering period at around three years of age. The flowers are white, tubular with five petals, and give off a faint fragrance similar to jasmine. The inflorescences are dense and arranged in clusters. The petals wither within two or three days, and several months later the fruit is formed. The fruit is a drupe, about 1.5 cm in diameter. It is green at first, then gradually turns yellow, and when ripe turns red. Its appearance is very similar to a cherry, so it is called "Coffee Cherry," and at this point it can be harvested. The coffee fruit contains two seeds inside, which are the coffee beans. These two beans face each other on their flat sides and stand upright pressed together. Each coffee bean is wrapped in a thin outer membrane called silver skin; outside the silver skin there is also a yellow outer layer called the endocarp. The entire coffee bean is surrounded by a sticky mucilaginous substance, forming soft and sweet-tasting coffee pulp, with the outermost layer being the outer skin.
II. Types of Coffee Trees
At present, the world's highest-quality coffee beans mainly come from the three major varieties: Arabica, Robusta, and Liberica, which is mainly due to the coffee trees of these three places.
1. Arabica Coffee Tree
Arabica originated in Ethiopia, and its coffee bean production accounts for about 70% of total global production. World-famous coffees such as Blue Mountain coffee and Mocha coffee almost all belong to the Arabica species. Arabica coffee trees are suitable for cultivation in high mountain areas with large temperature differences between day and night, as well as in soil with lower humidity and good drainage; the ideal altitude is 500-2000 meters, and generally the higher the altitude, the better the quality. Arabica coffee trees have certain requirements for soil fertility, humidity, sunlight, and shade, and this tree species has weak resistance to pests and diseases, is easily damaged, and its annual yield per unit area is also relatively low.
2. Robusta Coffee Tree
Robusta originated in Congo, Africa, and its production accounts for about 20%-30% of the global total. Robusta coffee trees are suitable for planting in lowlands below 500 meters above sea level. They have extremely strong adaptability to the external environment and can withstand harsh climates and pest damage. They also do not require much manual care in steps such as land preparation, weeding, and pruning, and can be left to grow in the wild. They are an easy-to-cultivate coffee tree. However, their flavor is more bitter than Arabica, and their quality is also considerably inferior, so they are mostly used to make instant coffee. The coffee sold in ordinary fast-food restaurants mainly uses Robusta coffee beans as the raw material. Because its origin is in Africa, most Africans also drink Robusta coffee. Robusta coffee trees have strong resistance to pests and diseases, are not easily damaged by agricultural hazards, have higher annual yield per unit area, can use machines for large-scale harvesting, and overall production costs are lower than those of Arabica coffee.
3. Liberica Coffee Tree
The origin of the Liberica coffee tree is Liberia in Africa. Its cultivation history is shorter than the other two coffee trees, so its planting areas are limited to a few places such as Liberia, Suriname, and Guyana, and its production accounts for less than 5% of the global total. Liberica coffee trees are suitable for planting in lowlands, and the coffee beans they produce have an extremely strong aroma and bitterness.
Harvesting of Coffee Beans
Coffee beans are the seeds produced by the coffee tree. After 3-4 years of growth, the coffee tree gradually matures and begins to bear fruit, and the fruits line up along the branches in strings or cluster together. Outside the seed is a layer of fruit skin, and once it turns red it can be picked. Beneath the red skin (exocarp) there is a layer of pulp (mesocarp), inside which is a thin small layer, and further inside is a parchment-like substance—the endocarp. Inside all these fruit layers there are usually two beans facing each other on their flat sides, and the beans are covered with a thin membrane or outer skin.
The maturity period for most Arabica coffee beans is June-August, and for Robusta coffee beans it is September-October. Therefore, although in some countries where the dry and wet seasons are not obvious, such as Colombia and Kenya, there are two flowering periods in a year, meaning two harvests, one large and one small, strictly speaking there is only one harvest per year.
Because regions differ, harvest periods also vary. Areas north of the equator (such as Ethiopia and Central America) generally harvest once from September to November. South of the equator, such as Brazil and Zimbabwe, although the harvest period can last until August, the main harvest is in April or May. Countries in equatorial regions, such as Uganda and Colombia, can harvest throughout the year, especially those plantations that make good use of various different altitudes. Therefore, newly harvested coffee beans may be available during most of the year.
As far as picking itself is concerned, there are two methods: one is strip picking, which means walking through the plantation once and picking all the beans; the other is selective picking, which means walking between the trees several times at intervals of 8-10 days and picking only those red berries that are fully ripe. Selective picking is more expensive and labor-intensive than strip picking, and is generally used only for Arabica coffee beans, especially those Arabica coffee beans that need to be washed.
The number of coffee beans picked depends on many factors, the most obvious being the height of the trees and the layout of the farm or plantation. On an ordinary farm, the average picker can pick 50-100 kg per day. However, only 20% of this weight is actually coffee beans, so on average each picker can only pick 10-20 kg of coffee beans. Coffee beans are packed in bags with a standard weight of 45-60 kg. Therefore, a worker needs 3-6 days to fill one bag.
It has been calculated that the cost of harvesting on a plantation or farm is half of the total annual cost. In Brazil, people have made many attempts to use mechanical picking to reduce these costs. This kind of machine can straddle the coffee trees and shake the branches, so that the berries that have become loose because they are fully ripe fall into the hopper. Mechanical pickers are only suitable in areas with relatively good natural conditions, and they need to be adjusted in advance, because this kind of machine can only be used where the trees can be planted very straight in rows, and afterward the mechanically picked coffee beans also need to be inspected to remove leaves and branches that have fallen into the hopper.
Therefore, a large portion of coffee is picked by hand, which requires a great deal of seasonal labor, and pickers must also be careful not to pick unripe, bad, or overripe coffee beans, because they will affect the overall quality of the harvested coffee. Those coffee beans that are already not very good are classified as "ordinary," "sour," or "fermented," with the last being extremely poor quality.
Coffee Bean Processing
There are two methods for preparing coffee beans for the roasting process. The method chosen has a major impact on the final value and quality of the coffee. The cheapest processing method is called the "dry method." This method is used for lower-grade coffee beans, while higher-quality coffee beans are processed using the "wet method." The dry method is used for unwashed coffee beans. The wet method is used for thoroughly washed or semi-washed coffee beans. Apart from the relatively common use of the dry method in Brazil and Ethiopia, most Arabica coffee beans are processed using the wet method. In Indonesia, some Robusta coffee beans are processed using the wet method, but this is not common locally.
The above content is compiled by CoffeeHunters, a coffee news website.
