As for green coffee beans, it can be summed up in one word, that is, “although there are not many types, the taste is endless”.
Coffee trees live in the tropics, which require a hot climate, abundant rainfall, and good water permeability.
Green coffee refers to the fruit of the coffee tree, which contains two seeds. A coffee tree generally takes 4-5 years to mature. The approximate amount of green coffee beans produced by each mature coffee tree per year can generally be processed into about 1 kg of roasted beans.
There are more than 100 species of coffee trees in the world today, but only two are widely cultivated: Coffea arabica and Coffea canephora (also known as Robusta). Corresponding to Chinese, it is Arabica, Robusta ( Robusta )
Arabica generally grows in areas above 900 meters above sea level. It is widely believed that the quality of Arabica coffee is superior to other varieties of coffee. Arabica coffee has relatively high requirements on natural conditions, such as climate, light and temperature must be adequate. Typically, specialty coffees are Arabica coffee.
Currently, the largest grower of Arabica is Brazil, while Colombia only produces Arabica coffee beans.
As the name Robusta suggests, Robusta coffee trees are not very demanding on the environment. This variety of coffee trees is more resistant to disease and climate change, and can grow at lower altitudes. Robusta coffee is generally more astringent and higher in caffeine. Because of its lower quality and price, it is often used to make instant coffee.
Of course, there are also a very small number of Robusta coffees that are considered to be of high quality. These coffee beans are generally used to mix with other coffees to increase the amount of crema in the coffee and improve the overall taste (body) of the coffee.
At present, the largest planting country of Robusta is Vietnam, and it is also planted in countries such as Africa, India and Southeast Asia.
Picking of coffee cherries
Different regions have different methods of harvesting coffee cherries. In the vast majority of areas, it is still manually picked. In some areas, harvesting is done by machine. Usually, the fruit that ripens first is picked first.
Processing of coffee cherries
After the green coffee beans are removed from the coffee cherries, a preliminary treatment is generally carried out. There are usually four ways, namely: sun drying, washing, semi-washing, and honey treatment.
Dry process/Natural method is the oldest and most primitive processing method of coffee beans. More than a thousand years ago, the Arabs processed coffee in this way. The harvested coffee cherries are placed on the terrace and directly exposed to sunlight (about 27 days to 30 days), and the moisture is reduced from 60% to only about 12%. This processing method is simple in concept and inexpensive, but there are many variables and risks; for a long time, it has been used to process beans that are not of such good quality.
Flavor presentation: soft acidity and uniform bitterness, thicker consistency, rich layers, and more obvious sweetness. , Good quality sun-dried beans will have a fruity or boozy aroma.
Sun-drying: Put the fresh coffee cherries into the sun-drying field for sun-drying. After about 2 to 4 weeks of continuous turning, they are naturally dried until the water content is about 12%. The coffee cherries are evenly heated. After drying, the coffee core and the outer skin will be separated, and then the pulp and outer skin will be removed by a sheller, and the screening will be completed.
Yemeni Mocha, Ethiopian Hara, Brazil, and Indonesian Sulawesi coffee beans are mostly processed by this method.
Washing method is a technique invented by the Dutch in the 18th century. It is suitable for rainy areas. Although the process is quite cumbersome, it is currently a relatively common green bean processing method, accounting for about 70% of the total coffee. The harvested berries are separated from most of the pulp from the coffee beans by a peeler, and then the shelled beans are guided to a clean water tank, soaked in water for fermentation to completely remove the residual pulp layer. Through water treatment, unripe beans and defective beans will be selected due to buoyancy, and the fermentation process is relatively easy to control, so the flavor is not like sun-dried beans, but it shows obvious fruit acid and complexity Slightly stronger and cleaner (without any negative notes like astringency or sharpness) in the glass. But it is also because it is too “clean”, and the richness of flavor is slightly weaker.
Flavor presentation: more intense acidity, clean, fresh and bright on the palate.
Sieve out floating beans: Rinse the coffee cherries with clean water and remove the unripe berries floating on the water.
Pulp removal: send the fresh fruit to the pulp screening machine to remove the peel and pulp.
Pectin removal: The seeds after removing the pulp are moved into the fermentation tank, and after about 16-36 hours of natural fermentation, the pectin on the surface is dissolved and then washed.
Drying and shelling: continue to expose to the sun for 1~3 weeks to reduce the water content to 12%, and then remove the shell with a shelling machine.
Washed beans are blue-green in color and beautiful in appearance. Guatemala, Colombia, Blue Mountain, Kona, Kenya, Java and Panama coffees are all washed beans.
Semi-washing method, also known as wet stripping or wet planing. The difference from other processing methods is that the coffee beans are not directly dried to a moisture content of 11-12% in the process, but the surface hard shell is removed when the moisture content is about 30-35%, so that The surface of the green beans is directly exposed, and then continues to be dried in the sun until it reaches a moisture content that is not perishable and convenient for storage. This secondary drying method makes the coffee beans present a swamp-like dark green appearance. Semi-washed coffee beans have lower acidity and a thicker character.
The flavor of semi-washed coffee is between natural and washed. This processing method is popular in Indonesia. Mandheling mostly adopts the semi-washed method. Brazil has also begun to use the semi-washed method in recent years.
The semi-washing method is somewhat similar to the water-washing method. First, the skin and part of the pulp of the coffee cherry berries are removed, and then the berries are dried in the sun. After the berries are dried, they are moistened, and then the pulp is removed with a special machine to remove the seeds.
The meaning of honey treatment comes from the sticky pectin layer of coffee beans before exposure, which feels sticky like honey; when the coffee pulp is separated from the coffee beans, the surrounding pectin layer is exposed to absorb moisture in the air And make the pectin layer sticky. The “honey” here refers to the mucous layer of the coffee pulp. The harvested fruit will also use a peeling machine to peel off the outer skin, leaving the pulp to be sun-dried, so that the sweetness of the pulp can enter the beans, and it does not take as long as the sun-dried method.
Flavor presentation: low acidity, high sweetness, and fruity aroma. The cleanliness of the mouthfeel is higher than that of sun-dried beans, and there is a fermented wine aftertaste after drying.
Peel removal: After washing the coffee cherries with water, remove the peel and leave the pulp
Sun-drying: Keep the pulp containing sugar and expose it to the sun together. At this stage, it must be partially stirred to prevent the green beans from becoming moldy.
To get green beans: remove the pulp, pectin and hull all at once after drying is complete.
Honey processing is currently a popular processing method, and Central American countries such as Costa Rica and El Salvador are good at it.
Classification and Rating
Green coffee beans are generally sorted and graded by size. After sorting, it will be packed into different sacks.
Caffeine is a naturally occurring compound. Worldwide, people have found caffeine from the leaves, seeds and fruits of more than 60 kinds of plants. Decaffeination refers to the process of removing caffeine from these plants.
There are three common methods of decaffeinating coffee.
The first is direct contact
This method generally uses dichloromethane. This is a relatively common organic solvent with low toxicity. Soak green coffee beans with a solution of dichloromethane, and the caffeine in the beans is dissolved in the solvent, thereby detaching from the coffee beans. Finally, remove the coffee beans. At this time, the solution should not be completely removed, and there will be some residue. However, the boiling point of dichloromethane is very low (40 degrees), and it can easily be heated to remove residues. Moreover, this temperature is much lower than the temperature at which coffee is roasted. Therefore, the international community generally recognizes the safety of the direct contact method.
The second is the Swiss washing method
Mainly through flavored waters that are already full of coffee flavor components but without the caffeine. The caffeine in the freshly brewed beans diffuses into the water without the flavor being lost.
The third is natural decaffeination
This method is to decaffeine coffee beans through methods such as sunlight.
Sustainability in the coffee industry
Sustainability in the coffee industry is also crucial in coffee production. The three cores of these are
- Environment: Minimize the impact on the local natural environment during coffee processing
- Economical: use more efficient cultivation and processing methods to reduce the consumption of various resources
- Society: Improving the income and quality of life of coffee practitioners
At present, many organizations are already engaged in this work, such as Fairtrade, Rainforest Alliance and so on.