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Popular coffee bean processing methods - Choosing beans and skillful roasting techniques

Coffee processing is an art that requires meticulous attention and in-depth knowledge. Each step in this process significantly influences the final flavor of the coffee. In this article, we will explore how to select coffee beans and skillful roasting methods to create high-quality coffee beans.

The structure of a coffee bean

The coffee cherry is not just a simple seed but a complex structure composed of multiple layers. Each layer, from the outer shell to the inner core, affects the quality and flavor of the coffee. Understanding this structure helps optimize the processing procedure.

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The structure of a coffee bean

  1. The Bean: The most critical part, containing most of the flavor and caffeine.

  2. Parchment: A thin layer protecting the bean, preserving its flavor.

  3. Silver Skin: A thin layer that contributes to the aroma when roasted.

  4. Husk: The hard protective layer that must be removed before roasting.

  5. Mucilage: Protects the fruit from insects, crucial in honey processing.

  6. Fruit Meat: The sweet part, containing the coffee cherry's natural sugars.

  7. Outer Skin: The outermost layer, whose color changes according to the ripeness of the fruit.

Each layer of the coffee cherry contributes to the final flavor and quality of the coffee bean. The pre-processing and processing procedures must be carried out carefully to preserve these characteristics.

How to select good coffee beans for harvesting

Selecting coffee beans is the first and most crucial step in the coffee processing chain. To ensure quality, coffee beans must be harvested when they are evenly ripe, with a uniform color, and free from damage or mold. High-quality coffee beans typically have slightly green stems, ensuring they are free from pests or diseases.

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Coffee harvesting

Harvesting coffee beans that are unevenly ripe or still green, with an underdeveloped mucilage layer around the bean and the silver skin just beginning to turn green, will result in a lower bean density. Such coffee beans, when roasted and brewed, will produce a weak, bland coffee lacking the distinctive aroma.

Therefore, selecting coffee beans properly requires experience and keen insight from the harvester. The meticulousness in this step not only affects the quality of the coffee beans but also determines the final flavor of the beverage..

The processing of coffee beans involves three methods 

There are three main methods for processing coffee beans: dry processing, wet processing, and semi-wet processing. Each method has its characteristics and influences the coffee's flavor uniquely.

Processing coffee beans by the dry method 

Dry processing is a traditional method in which coffee beans are sun-dried naturally. This process requires a large space and a long drying period, but it produces a rich and authentic coffee flavor.

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Processing coffee beans by the dry method 

This coffee pre-processing method stands out for its simplicity and labor efficiency. However, a significant drawback is the extended drying time for the coffee, which increases the risk of the beans becoming damp and moldy from within. This becomes even more problematic when the weather is unfavorable, with prolonged periods of insufficient sunlight directly impacting coffee quality.

For premium coffee varieties, the application of this method is often carefully considered. Yet, when carried out meticulously, with a focus on a high rate of ripe coffee cherries, strict control of drying time and temperature, and effective prevention of dampness and mold, the flavor of the finished coffee can significantly surpass that produced by other pre-processing methods.

Therefore, despite certain limitations, with careful attention and strict control at each step, this method is not only a convenient choice but can also create coffee beans with unique and rich flavors.

Processing coffee beans by the wet method

The wet processing method involves soaking coffee beans in water to remove the outer pulp and mucilage layer. This helps produce coffee with a cleaner and more refined flavor.

In the wet pre-processing method of coffee, each step in the process requires meticulousness and accuracy. Starting with the harvesting phase, selecting uniformly ripe coffee cherries is extremely important, and the presence of green cherries should be minimized. After harvesting, the coffee is depulped to remove the outer mucilage layer, then the remaining beans are fermented.

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Processing coffee beans by the wet method

The fermentation process is a critical step, completed when the outer parchment becomes rough and is no longer slimy. Next, the coffee beans are washed clean and dried. During the drying phase, it is necessary to spread the coffee evenly and avoid direct drying on the ground to prevent moisture absorption. The drying is considered sufficient when the coffee beans are uniformly dry and do not break when bitten.

The wet pre-processing method requires precision in every step, from harvesting to fermentation and drying. It is not only a technical process but also a demonstration of the farmers' skill and expertise. This method highlights the unique characteristics of the coffee variety, especially with Arabica beans. Thanks to the natural fermentation process, Arabica beans processed by the wet method will have a pure, consistent flavor rich in aroma.

In contrast, Robusta beans, with their higher acidity, may develop a harsh sour taste when processed this way, which might not suit everyone's palate. Therefore, Robusta beans are often processed using the dry method to enhance their unique characteristics and flavor.

Processing coffee beans by the honey method

Semi-wet processing, also known as the honey process, is a combination of the two methods mentioned above. Coffee beans are partially processed by the wet method, then dried. This creates a balanced flavor profile that is both rich and delicate.

Phương pháp chế biến honey
The honey processing method

This coffee pre-processing method stands out for its faster drying capability compared to traditional dry processing methods. A major benefit is the reduction in the area required for drying yards and the amount of labor. Under favorable weather conditions, this method can produce high-quality coffee products. However, in adverse weather conditions, investing in dryers and dehulling equipment becomes necessary to maintain product quality.

During the drying process, it's important to avoid the situation where coffee beans stick together, affecting the uniform drying process and reducing product quality. This control requires careful attention and meticulous intervention.

These coffee pre-processing methods are fundamental and widespread in the coffee industry. Each method has its own strengths and weaknesses and contributes to the unique flavor profile of each coffee type. However, the coffee market continues to evolve with many new pre-processing methods and unique variations. The development of technology and the limitless creativity of humans will surely bring advanced techniques, creating new value in the coffee industry.

HQJ Coffee School - Where green coffee experts are trained

HQJ Coffee School is a leading, professional training center specializing in coffee processing techniques education and guidance. Here, students learn from top experts in the industry, who have extensive experience and high-level expertise in coffee.

The training program at HQJ Coffee School includes various courses, from basic to advanced, suitable for all levels, from beginners to those with experience. The courses focus not only on theory but also on practice, enabling students to master and apply coffee processing techniques in real life.

HQJ Coffee School is not just a place to train green coffee experts, but also a venue for coffee lovers to meet, exchange knowledge, and share their passion. It is an ideal destination for anyone looking to conquer and understand more about the rich and diverse world of coffee.

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