The current popular coffee processing method.
The different coffee processing method make a big difference in both the aroma and taste of coffee beans.
Coffee processing is the way to exploit the full flavor of coffee. Depending on the type of coffee of each geographical area; people will choose the most appropriate processing method. And each processing method is a standard to create a special coffee flavor, satisfying the diverse needs of customers.
Even when the coffee is ripe and the conditions are perfect; if the processing method is not good, the quality of coffee beans can be significantly reduced. Besides, some processing methods require a lot of time and complicated techniques; so choosing the appropriate processing method is an important decision for coffee suppliers.
Currently, there are 3 methods of coffee processing that are commonly applied in the world; including dry processing, wet processing and honey processing. In addition, recently, some places have begun testing methods of anaerobic fermentation, or using catalysts. These methods are in the process of testing and have not yet been put into common production.
I/ Dry processing method/ natural coffee processing method / Unwashed
This is the oldest and easiest method of processing, suitable for areas with limited water resources. This method is commonly used in Brazil, Ethiopia and Vietnam with the Robusta Coffee product line.
Fruit coffee after picking will be kept whole skin, spread into thin layers to expose in the sun. This process takes several weeks to achieve a certain dryness, avoiding rot and mold. In order to speed up the processing process, some places use a fan to heat steam to dry and control the fermentation environment, overcome erratic weather. After the coffee has dried; people will remove the skin and dried meat by mechanical methods to get coffee beans.
Advantages of dry processing method:
The process of accumulating nutrients in the seeds takes place slowly to make the seeds flavorful and strong, bringing a sweet, less sour taste.
Disadvantages of dry processing method:
The quality of coffee beans is heterogeneous due to many factors such as weather, light level of the sun, long drying time.
II/ Wet coffee processing method
Freshly harvested fruit will remove the skin and flesh of the coffee with a dedicated machine. After separating the seeds, the coffee beans will be put into a water tank to carry out the fermentation process; removing the remaining mucus layer outside the husk. The time of this fermentation depends on the climate of each region. In areas with high temperatures, fermentation will occur faster and vice versa.
The wet processing process consists of the following stages:
- After picking, wash the coffee fruit with water to remove impurities to create a homogeneous batch.
- Next, they rub the coffee husks with a specialized machine, at this time the mucus layer is still lingering on the coffee beans.
- Continue putting green coffee beans in fermented soaking tanks for about 12 – 72 hours. At this stage, it is necessary to check and monitor continuously for perfect fermentation process. Thanks to that the best qualities of coffee beans have the opportunity to stand out, typically taste and taste.
- At the end of the fermentation; coffee beans will be washed again and brought to the drying platform for about 4 – 10 days.
- After drying, the coffee beans are clean, uniform and light beige.
Most Arabica coffee in the world is processed in this way; which is why pure Arabica coffee has a distinctive sour taste.
Advantages of wet processing method
Uniform coffee flavor, hygienic, characteristic sour coffee, outstanding coffee bean quality. Fast coffee processing time.
Disadvantages of wet processing methods
Processing requires a lot of water and susceptible to fermentation making the coffee sour if soaked in water for too long.
III/ Honey processing method
The method is native to Costa Rica and is commonly used in central America.
This is a semi-dry and semi-wet method; The basic rule is to only choose ripe coffee when you harvest. Meanwhile, the sugar content in the fruit will reach the highest level and reach the best quality for processing by this method. Completely separate the skin of the coffee fruit; Depending on the level of fermentation desired, people will peel more or less or sometimes not peel the coffee flesh layer.
Then, put the coffee beans on the platform to dry in the natural sun; depending on the weather and drying time, the quality and flavor of the coffee are different.
Processing by honey method consists of 4 levels: White, Yellow, Red, Black; depending on the level of separated coffee.
White Honey: 10-15% of mucus is on the grain
Yellow Honey: 15-50% of sticky mucus
Red Honey: 50-90% of the mucus is on the husk
Black Honey: there is 90-100% of mucus on the husk
Because the rice layer of ripe coffee is viscous and viscous, it is called honey processing method, not honey-impregnated coffee.
Advantages of honey processing method.
Green coffee after preliminary processing will keep the sour taste just enough, uniform, round taste. It is usually more acidic than washed coffee, with a strong sweetness and a complex mouth feeling.
This method is also very environmentally friendly, because very little use of water and manual sun exposure.
Disadvantages of honey processing method.
Requires complex handling, high technology and appropriate climate. Because the preservation of coffee processed by honey method is very difficult; especially in the rainy season, the dried viscous layer can absorb moisture and form an appropriate environment for mold and fungus to grow and harm the kernel inside.
IV/ Other coffee processing methods
1/ Anaerobic method
Anaerobic fermentation (= without oxygen) is one of the latest methods of processing coffee; especially high-class coffee products. The anaerobic process is similar to the washing process but the fermentation is carried out in a completely sealed tank and lacks oxygen. This method is still in the testing phase; but the results show that anaerobic method brings a wild, unexpected and complex flavor.
2/ Carbonic Maceration
This method is similar to anaerobic, and imitates the wine production process. The biggest difference with the anaerobic process is that the coffee fruit is fully fermented; and breaks down the cell walls of the flesh inside out. All the flavors of the fruit meat are infused and the beans are fermented; and the Carbonic Maceration delivers an incredibly crazy and amazing flavor.
3/ Giling Basah
Sounds something not related to coffee but in fact it means “wet hulled” in Indonesian language. As you might then expect, it is only common in Indonesia. The Giling basah method is similar to the wet method; but only drying with 30-35% moisture (11-12 % in washed process). After initial drying the parchment is removed from the beans and the “naked” beans are then dried again until they are dry enough to be stored. Giling basah yields earthy flavors such as wood, mustiness, spice and tobacco; that is why coffee experts do not appreciate this method.
Although there are many different methods of coffee processing; in general, they must follow the principle: peeling the skin from ripe fruits and reducing the moisture of the coffee beans to 10-12%.
Each method of coffee processing has certain advantages / disadvantages. Therefore, depending on equipment conditions, regional geographic conditions and market segments; suppliers will choose the appropriate method of coffee processing.