Barista course

The generating environment of coffee trees

In botany, coffee trees belong to the evergreen trees of the subgenus Rubiaceae, and coffee beans, commonly known as coffee beans, are actually the seeds of the fruit of coffee trees, just because they are shaped like beans. Climate is the decisive factor for coffee cultivation. Coffee trees are only suitable for growing in the tropics or subtropics, so the zone between latitude 25 degrees south and north is generally called coffee belt or coffee area. However, not all the land located in this area can produce good coffee trees.

1. Planting conditions of coffee trees the ideal planting conditions for coffee trees are: the temperature is between 15-25 ℃, and the annual rainfall must reach 1500-2000 mm. At the same time, the rainfall time should be in line with the flowering cycle of coffee trees. Of course, in addition to the seasonal rainfall, there should also be fertile soil and good drainage. In addition, although sunlight is an indispensable element for the growth and fruit of coffee, too strong sunlight will inhibit the growth of coffee trees, so various producing areas will usually cooperate with the planting of some shade trees. The ideal altitude for coffee trees to grow is 500-2000 meters. It can be seen that the conditions for the cultivation of high-quality coffee are very strict: sunlight, rainfall, soil, air temperature, as well as the way coffee beans are harvested and the production process will affect the quality of coffee itself.

2. The first flowering period of the white flower and red fruit coffee tree is about three years old. the white five-petal tube-shaped flowers are filled with a faint fragrance of jasmine, and the inflorescences are arranged in dense clusters. The petals will wither in two or three days and bear fruit after a few months. The fruit is a drupe with a diameter of about 1.5cm. It turns green at first, then turns yellow gradually, and turns red when ripe. It is very similar to cherries, so it is called cherry coffee (Coffee Cherry). It can be harvested at this time. Coffee fruit contains two seeds, namely coffee beans. The two beans are connected face to face with each other on one side of the plane. Each coffee bean has a thin outer film, which is called silver skin, and its outer layer is covered with a yellow outer skin, called endocarp. The whole coffee bean is wrapped in a sticky pulp to form a soft and sweet coffee pulp with the outermost shell.

Types of coffee trees

At present, the best quality coffee beans in the world mainly come from Arabica, Robusta and Liberia, which are mainly proud of the coffee trees in the three places.

1. Arabica coffee tree

The country of origin is Ethiopia, and its coffee bean production accounts for 70% of the world's output; the world-famous Blue Mountain Garffin, mocha coffee and so on are almost all Arabica species. Arabica coffee trees are suitable for growing in high mountains with large temperature difference between day and night, as well as low humidity and well-drained soil; the ideal altitude is 2000 meters, the higher the altitude, the better the quality. Arabica coffee trees require fertile soil, sufficient moisture, proper sunshine and shade, poor resistance to diseases and insect pests, and low annual output per unit area.

2. The Robusta coffee tree originated in the Congo in Africa, and its output accounts for about 20% of the world's output. 30%. The Robusta coffee tree is suitable for planting in the lowlands below 500 meters above sea level, has a strong adaptability to the outside world, can resist adverse weather and insect pests, and does not need much manual care during soil preparation, weeding and pruning, and can be allowed to grow in the wild. It is a kind of coffee tree that is easy to cultivate. But its flavor is more bitter than Arabica, and its quality is much lower, so it is mostly used to make instant coffee. In general, the coffee sold in fast food restaurants mainly uses Robusta coffee beans as the material. Because it is made in Africa, most Africans drink robusta coffee. Robusta coffee trees have strong resistance to diseases and insect pests and are not vulnerable to agricultural diseases. the annual output of coffee trees per unit area is higher and can be harvested in large quantities by machine. generally speaking, the production cost is lower than that of Arabica coffee.

3. The Liberian coffee tree is from Liberia in Africa, and its cultivation history is shorter than that of the other two kinds of coffee trees, so the planting place is limited to a few places such as Liberia, Suriname, Gaiana and so on. As a result, the output accounts for less than 5% of the world's output. The coffee tree of Liberia is suitable for planting in the lowlands, and the coffee beans produced have a strong aroma and bitter taste.

The growth cycle and picking of coffee

Coffee beans are the seeds of coffee trees. After three or four years of growth, the coffee tree matures and begins to bear fruit, with one fruit arranged in clusters or clusters along the branches. The outside of the seed is a layer of peel, which can be picked as soon as it turns red. Under the red skin (exocarp) there is a layer of pulp (mesocarp), which is a small thin layer, and then a layer of parchment-like substance-endocarp. In all of these peels, there are usually two beans with opposite planes, and the beans have a thin film or skin on the outside. Most Arabica coffee beans mature from June to August and Robart coffee beans from September to 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 a year, that is, two harvests, strictly speaking, only once a year. Due to different regions, the harvest time is also different.

Regions north of the equator (such as Ethiopia and Central America) are generally harvested in September-November. South of the equator, such as Brazil and Zimbabwe (Zimbabwe), although the harvest can last until August, the main one is in April or May. Countries in the equatorial region, such as Uganda (Uganda) and Colombia, can harvest all year round, especially those plantations that make good use of different elevations. As a result, there may be new coffee beans for most of the year.

As far as picking itself is concerned, there are two ways: one is picking in pieces, that is, picking all the beans after a walk in the garden, and the other is selective picking, that is, at intervals of 8-10 days. walk between the trees a few times and pick only the ripe red berries. Selective picking is more expensive and labor-intensive than picking in pieces, and it is generally only used for Arabica coffee beans, especially those that need to be washed. The number of coffee beans picked depends on a variety of factors, the most obvious being the height of the trees and the layout of the farm or plantation. On average, the average farm picker can pick 50-100 kilograms a day. But only 20% of these weights are real coffee beans, so the average picker can only pick 10-20 kilograms of coffee beans. The coffee beans are packed in bags with a standard weight of 45-60 kilograms. As a result, it takes 3-6 days for a worker to fill a bag. It has been calculated that the cost of harvesting a plantation or farm is half of the total cost of the year.

In Brazil, people have tried many times to reduce these costs by mechanical picking. The machine can shake branches across the coffee tree so that the berries that become loose because they are ripe will fall into the funnel. Mechanical pickers only work in areas with better natural conditions, and they need to be adjusted in advance, because they can only be used where the trees can be planted in rows straight, and afterwards need to check the coffee beans picked by the machine. pick out the leaves and branches that have fallen in the funnel. Therefore, a large part of the coffee is picked by hand, which requires a lot of seasonal work, and pickers should be careful not to pick coffee beans that are not ripe, bad or too ripe, as they will affect the overall quality of the coffee harvested. Coffee beans that are not so good are classified as "ordinary", "sour" or "fermented", and the last one is very bad.