May 25


The Influence Of Processing Methods In Green Coffee Beans

By Hanson Cheng

May 25, 2023

Green coffee beans are the unroasted seeds of the Coffea plant, and are known for their potential health benefits and distinctive flavor profiles. However, before they can be brewed into a hot cup of coffee, green coffee beans must go through a series of processing methods that can significantly impact their quality and characteristics.

These processing methods, which include harvesting, drying, and milling, play an essential role in determining the final taste and aroma of the coffee. In this article, we will explore the importance of processing methods in green coffee beans and how they can impact the quality of the final product.

Overview Of Green Coffee Beans

Green coffee beans are the unroasted seeds of the Coffea plant. They are green in color and have a neutral flavor. The term ‘green coffee beans’ refers to coffee beans that have not undergone the roasting process. The process of roasting changes the chemistry of the coffee beans, altering their aroma, flavor, and color.

Green coffee beans are therefore considered raw coffee. They must be processed before being sold and consumed. Green coffee beans are commonly processed through two methods, wet or dry processing. Both methods have implications on the quality of the coffee beans and the final cup of coffee. Understanding the processing methods is essential for coffee producers, roasters, and consumers to make informed decisions.

Importance of Processing Methods

The processing methods used in the production of green coffee beans play a critical role in the flavor and aroma profile of the final product. The methods used determine the quality and characteristics of the beans, which are essential considerations for coffee buyers, roasters, and consumers. In the coffee industry, green coffee beans are typically processed through dry, wet, or semi-dry/washed methods.

The most common method is the wet process, which involves removing the outer layers of the cherries using water and fermentation. The wet process aims to produce coffee beans with a clean and consistent cupping profile, highlighting the bright acidities and floral notes of the beans. The dry process, on the other hand, involves drying the cherries intact in the sun. This method produces coffee beans with a more complex and rich flavor profile, with a fruitier and sweeter taste compared to the wet-processed beans.

The semi-dry or washed process combines aspects of both methods, creating a distinctive flavor profile with moderate acidity and sweetness. Roasters consider the processing method used when evaluating green coffee beans for purchase, as it can significantly impact the final product’s taste and character. Generally, the green coffee beans’ processing methods, along with other factors such as origin, elevation, and variety, distinguish the different coffee bean types available on the market.

Processing Methods For Green Coffee Beans 

Wet Processing

Wet processing, also known as washed processing, is a method of removing the outer layers of the coffee cherry through immersion in water. Once the coffee cherries are harvested, they are sorted, and any unripe or damaged cherries are removed before the remaining cherries are depulped. The remaining mucilage and parchment layers are subsequently removed through fermentation in water tanks.

The fermentation process is essential in separating the coffee beans from the outer layers and involves the development of natural enzymes that break down the mucilage. Wet processing has been traditionally utilized in regions where water is abundant, and the process is often associated with increased acidity and brightness in the coffee’s flavor profile. The process results in a cleaner, more uniform, and consistent cup of coffee.

Wet processing also has specific environmental advantages, as it reduces water pollution compared to dry processing and minimizes the amount of water used. However, wet processing has some shortfalls, including increased production costs associated with the extensive use of water and energy needed to power machinery and water pumps. Moreover, wet processing can lead to high levels of wastewater that may contain pollutants and cause environmental degradation if not efficiently treated, affecting the quality of the surrounding freshwater resources.

Dry Processing

Dry processing is a prevalent method used to process green coffee beans that involves drying the cherries in the sun. This process usually takes place in areas with arid climates and involves sun-drying the cherries to extract the coffee beans. Dry processing has several advantages, including low-cost operations, and it requires minimal equipment and resources. However, the process requires strict monitoring, as the drying process can easily go wrong, leading to low-quality coffee. The quality and flavor of coffee produced through dry processing are distinct and unique, with fruity and fermented notes.

Semi-dry Processing

Semi-dry processing, also known as pulped natural or honey processing, is a hybrid of wet and dry processing methods. In this process, the outer fruit layer is partially removed, leaving some sticky fruit pulp attached to the beans, which are then sun-dried. This processing method offers some advantages over both wet and dry processing, such as the unique flavor profile created by the combination of the sweetness from the pulp and the acidity from the coffee beans.

Additionally, this method is less expensive than wet processing because it requires less water and energy. However, semi-dry processing can also pose some challenges, such as inconsistent drying due to the sticky pulp, which can lead to mold development and over-fermentation.

As a result, farmers must carefully monitor the drying process to ensure that the beans are properly dried and do not spoil. Despite these challenges, semi-dry processing has become increasingly popular among specialty coffee producers because of the unique flavors it creates and its relative cost-effectiveness compared to wet processing.

Factors Affecting Processing Methods


The climate conditions of a region play a crucial role in determining the quality and taste of green coffee beans. The temperature, humidity, rainfall, and sunlight of a location greatly impact the growth and development of coffee trees. Coffee trees thrive in temperatures ranging from 18°C-26°C, with rainfall of 1500mm-2000mm per annum distributed throughout the year, providing optimal growth conditions for the trees. The soil type and topography of a region also affect the coffee beans’ quality and taste. Coffee produced in high altitudes has desirable characteristics such as high acidity, bright and crisp flavors, and complex profiles.

Areas with high humidity levels have slower cherry maturation, enabling the beans to develop a higher sugar content, resulting in a sweet and fruity taste in coffee. Humidity levels also affect the drying process of the beans, where a dry and hot climate is ideal for quick and even drying. The amount of sunlight helps the coffee cherries ripen, contributing to the quality of the beans. Coffee grown in regions with abundant sunshine produces beans with stronger flavors.

Climate change has led to alterations in coffee production, affecting the coffee industry worldwide. Unfavorable weather patterns lead to changes in the quality and quantity of the beans produced. Changing rainfall patterns impact coffee farming, resulting in low yields and poor-quality beans. Increased temperatures, droughts, and pests and diseases can damage coffee trees, affecting the production and quality of coffee. The effects of climate change require adapting coffee farming techniques and implementing sustainable practices to mitigate the negative impact.

The climate of a region plays a significant role in determining the flavor and quality of green coffee beans. The temperature, humidity, rainfall, soil type, topography, and sunlight all contribute to the growth and development of coffee trees. Climate change poses a threat to coffee production worldwide, requiring sustainable practices and adaptation in coffee farming techniques to ensure the longevity of the coffee industry.


Altitude is a crucial factor in determining the flavor and quality of green coffee beans. Coffee plants grown at high altitudes experience less oxygen and carbon dioxide, leading to slower growth and development. This condition causes the plants to produce denser, harder, and brighter coffee beans than those grown at lower altitudes. High-altitude coffee beans usually have a higher sugar content, which leads to a sweeter profile, more acidity, and a fruity aroma, making them highly sought-after in specialty coffee markets.

On the other hand, beans grown at lower altitudes tend to have a more straightforward and relatable flavor profile, characterized by nutty and earthy tones. The lack of high altitude stress means beans from these regions have a large body and low acidity, making them more palatable and suitable for mass-market consumption. Additionally, lower altitude regions are typically warmer and experience more direct sunlight, leading to beans with a higher chlorogenic acid content and lower sugar content.

To put altitude’s role into perspective, coffee grown at similar altitudes but different latitudes have noticeable flavor differences. For instance, beans grown at high altitudes in some Central American countries have a tangy and bright acidity and a citrusy flavor profile, while beans grown at the same high altitudes in East Africa have a floral and tea-like flavor profile and balanced acidity. Therefore, altitude is among the critical variables coffee roasters and buyers consider when rating green coffee beans’ quality.

Harvesting Method

Harvesting Method is an essential aspect of processing green coffee beans. The method used to harvest coffee beans affects both the coffee bean’s flavor and quality. Generally, there are two primary methods of harvesting coffee beans that hold significant relevance in the coffee industry – handpicking and strip picking. Handpicking involves picking coffee cherries individually as they ripen, while strip picking involves stripping all cherries off the coffee plant with a harvesting machine.

Handpicking is the most commonly used method and is often preferred by farmers who produce high-quality coffee. This is because the farmers can select only the ripe coffee cherries, resulting in a more consistent and even roast. Additionally, as most farms that produce high-quality coffee are too steep to utilize machinery, handpicking is the only option. In contrast, strip picking is often used for farms with flatter topography, as it is more efficient and requires less labor, resulting in lower harvesting costs.

However, strip picking often results in lower quality beans as it is difficult to differentiate between ripe and unripe coffee cherries. There is a third harvesting method called selective picking, which combines the two. Selective picking involves handpicking only the ripe cherries while using machines to strip the whole tree of all its cherries. This method is used to minimize labor costs while still ensuring high quality and producing a more consistent, even roast.

It is essential to note that the harvesting method affects the quality of green coffee beans, making it crucial for buyers and roasters to have this information before purchasing. The method used can affect flavor, aroma, and acidity significantly. For example, if the beans are not harvested at the proper ripeness, they will lack sweetness and may have an unpleasant aftertaste. Therefore, it is important to know the harvesting method used to ensure a high-quality and consistent product.

Equipment Availability

Equipment availability plays a fundamental role in the green coffee bean processing methods. Access to necessary machinery such as pulpers, fermentation tanks, and drying beds, depending on the processing method, is paramount to the successful outcome of the final product. For instance, the wet processing method requires pulpers to remove the skin and fruit from the coffee beans and fermentation tanks to break down the mucilage layer, whereas the dry processing method relies on drying beds to expose the beans to sunlight and air for extended periods.

Without this equipment, processing coffee using the appropriate methods becomes challenging, if not impossible. Moreover, the availability of equipment affects the cost and quality of the final product. For small-scale farmers who lack the necessary equipment, their only option is to sell their coffee cherries to wet mills, incurring additional costs resulting in a reduced profit margin.

Conversely, farmers who own or have access to the equipment can process their coffee cherries, create a unique taste profile, and charge a higher price for their coffee beans. Therefore, the availability of processing equipment shapes the coffee supply chain and ultimately influences the farmers’ income and the overall quality of the coffee produced.

Impact of Processing Methods on Green Coffee Beans

Physical Characteristics

The physical characteristics of green coffee beans are essential in determining the resulting quality of the final cup of coffee. The size and shape of the beans play a crucial role in the roasting process, as well as in the extraction process. Larger beans tend to roast more evenly, while smaller beans tend to roast faster and may become burnt if not closely monitored.

The shape of the bean also affects the flow of heat during roasting, which can impact the final flavor profile. Another critical factor in the physical characteristics of green coffee beans is the moisture content. Beans with too high or too low moisture content can negatively affect the roasting process, leading to inconsistent roasts and inferior quality coffee.

The density of green coffee beans also plays a role, with denser beans roasting more slowly and evenly than less dense beans. In addition to the size, shape, moisture content, and density, the color of green coffee beans can also indicate quality. Beans with hues of blue or gray may have been improperly processed or stored, while beans with deep green or yellow tones typically indicate a high-quality product.

Chemical Composition

The chemical composition of green coffee beans plays a crucial role in determining the final cupping profile of the coffee. Understanding the chemical composition of green coffee beans is vital to the processing methods used on them. Green coffee beans have a unique composition of carbohydrates, lipids, proteins, minerals, and organic acids. The amount of these components varies depending on the coffee variety, growing conditions, and processing methods.

The carbohydrate content of green coffee beans is about 30-50% and consists mainly of polysaccharides such as cellulose, fructose, and glucose. The lipid content of green coffee beans ranges from 10-15% and consists mainly of triglycerides and fatty acids. Proteins make up approximately 10-15% of the green coffee bean and include different amino acids such as asparagine, glutamine, and alanine.

The mineral content in green coffee beans is essential for plant growth and development and includes calcium, magnesium, potassium, and sodium. Organic acids such as chlorogenic acids, quinic acids, and citric acid make up about 7-10% of the green coffee beans. The chemical composition of green coffee beans affects the taste and aroma of the final product. Chlorogenic acids, for instance, play a crucial role in the final cupping profile of the coffee.

Chlorogenic acids are reduced during roasting to form different aroma compounds that contribute to the unique flavor profile of coffee. Roasting different green coffee beans with different chemical compositions results in different flavor profiles. The presence of lipids in green coffee beans plays a vital role in the shelf life of coffee and its susceptibility to oxidation. The amount of protein in green coffee beans affects the formation of Maillard compounds, which contribute to the brown color and flavor of the coffee during roasting.

The minerals present in green coffee beans also affect the final cupping profile. Potassium, for instance, plays a role in coffee aroma and taste. The chemical composition of green coffee beans affects the final cupping profile of coffee. Roasters need to consider the chemical composition of green coffee beans when selecting processing methods and roasting profiles. Roasting different green coffee beans with different chemical compositions yields different flavor profiles, which is crucial in the coffee industry.

Cupping Profile

The cupping profile is a crucial aspect of coffee evaluation and is essential in determining the quality of green coffee beans. It involves measuring various sensory attributes of brewed coffee, including aroma, flavor, body, acidity, and aftertaste, among others. The cupping profile provides insight into the unique qualities of a particular coffee region or variety and helps in identifying defects and inconsistencies in processing methods.

During the cupping process, the coffee is prepared using controlled brewing techniques to ensure consistency and accuracy. The sensory evaluation is carried out by professional cuppers who have received specialized training and certification in evaluating coffee. The results of the cupping process are documented in a cupping form, which provides a detailed analysis of the coffee’s sensory attributes.

Processing methods have a significant influence on the cupping profile of green coffee beans. The different processing methods, including natural, washed, and honey processing, all contribute unique flavors and aromas to the coffee. Natural processing, for instance, results in a coffee with fruity flavors, while washed processing tends to produce coffees with bright acidity and clean flavors. Honey processing, on the other hand, produces a coffee with a unique sweetness and a pronounced body.

The cupping profile is useful in determining the market value of a particular coffee. High-quality coffees with unique and complex flavors are often highly valued in the specialty coffee industry, while coffees with flat and muted flavors are considered of lower quality. The cupping profile, therefore, plays a significant role in determining the price range of green coffee beans.

The cupping profile is an essential aspect of coffee evaluation and helps in determining the quality and value of green coffee beans. Processing methods have a significant influence on the sensory attributes of coffee, and the cupping process provides a useful tool in identifying these attributes.

Summary Of Findings

Overall, this study highlights the significant role that processing methods play in the quality and flavor of green coffee beans. The findings suggest that the type of processing method used greatly influences the chemical composition of the beans, resulting in different flavor profiles and sensory characteristics.

Specifically, wet processing methods were found to produce beans with brighter and fruitier flavors, while dry processing methods were associated with more earthy and nutty flavors. However, it is important to note that the impact of processing methods on the final product is influenced by various factors, including the origin of the beans and the roasting process. These findings have important implications for the coffee industry, as they suggest that processing methods can be manipulated to produce distinct flavor profiles that cater to different consumer preferences.

Therefore, coffee producers and roasters must consider the processing method used when selecting beans and developing their products. Moving forward, future research should continue to investigate the complex interactions between processing methods, origin, and roasting to develop a more nuanced understanding of how to achieve optimal flavor profiles and sensory attributes.

Implications for Coffee Industry

The study on the role of processing methods in green coffee beans has significant implications for the coffee industry. The findings of this study provide insights for coffee growers and processors to improve the quality of their products. The study highlights that the processing methods used in the preparation of green coffee beans significantly affect the quality and flavor of the coffee. Therefore, coffee growers can improve the quality and value of their product by carefully selecting the processing method.

By using appropriate processing methods, they can improve the flavor, aroma, and overall quality of the coffee beans. Additionally, the study offers insights for the coffee industry in terms of product differentiation. By using different processing methods, coffee producers can create distinctive flavors and textures in their coffee beans. This can help them create a unique selling proposition for their products and stand out in a crowded market.

The study highlights the importance of understanding consumer preferences and trends in coffee flavors and aromas. By using the appropriate processing methods to create unique flavors, the coffee industry can satisfy the changing tastes of coffee consumers. Moreover, the findings of this study can inform the development of industry standards for coffee processing. Standardization of coffee processing methods can help ensure consistent quality and flavor in coffee products. By establishing clear guidelines, the coffee industry can promote sustainable and ethical practices in coffee production.

The study highlights the need for further research to develop industry standards that take into account the diverse processing methods used by coffee producers worldwide. The study on the role of processing methods in green coffee beans offers valuable insights for the coffee industry. By carefully selecting processing methods, coffee growers can improve the quality and value of their product.

Different processing methods can also create distinctive flavors and textures in coffee, enabling coffee producers to differentiate their products. Moreover, industry standards for coffee processing can help ensure consistent quality and promote sustainable and ethical practices in coffee production. Further research is needed to establish industry standards that consider the diverse processing methods used in coffee production worldwide.

Future Research Directions

Firstly, more research is needed on understanding the mechanisms of chemical reactions affecting the flavor profile of the coffee during different processing techniques. Investigating the impact of different processing methods on the chemical composition of coffee beans will help to determine the best processing technique that can produce optimal coffee flavor and quality. Moreover, research should focus on the best practices for roasters and coffee growers for the best processing method of coffee beans in different regions for desirable flavors.

Secondly, there is a need to evaluate the environmental and economic sustainability of different processing methods of coffee beans to avoid the negative impact of coffee production on the environment. Studying the environmental impact of different processing methods should involve assessing the water consumption, energy, and chemical usage of coffee processing methods to identify the most efficient and sustainable techniques.

Lastly, expanding research into the effects of processing methods on coffee beans’ nutritional value could benefit coffee lovers’ health. Since coffee is a significant source of antioxidants and minerals, it would be valuable to investigate how processing methods affect the levels of these compounds and their bioavailability.

The role of processing methods in green coffee beans – FAQs

1. What are processing methods in green coffee beans?

Processing methods refer to the various ways of removing the outer layer (pulp) of coffee cherry to access the seeds or beans inside. These methods affect the flavor, acidity, and aromas of coffee because they influence the way the beans absorb or lose moisture, ferment, and dry.

2. What are the major types of processing methods for green coffee beans?

There are three main processing methods: washed, natural, and honey. Washed coffee involves removing the outer layer using water and friction, then drying the beans. Natural coffee involves sun-drying the whole cherries, then breaking them to release the beans. Honey coffee is a hybrid method that lies between washed and natural coffees.

3. What role do processing methods play in determining the flavor of green coffee beans?

Processing methods affect the flavor of coffee because they determine how the beans interact with the fruit sugars and microorganisms in the cherry. Washed coffees tend to have bright, clean, and fruity flavors, natural coffees tend to have heavier, sweeter, and fruitier flavors, while honey coffees tend to have a mix of the two.

4. How do processing methods affect the quality of green coffee beans?

Processing methods affect the quality of coffee by influencing the uniformity, cleanliness, and consistency of the beans. Poor processing can result in defects, such as mold, over-fermentation, or under-ripening, that can make the coffee taste unpleasant or inconsistent.

5. What are some challenges in choosing the right processing method for green coffee beans?

Choosing the right processing method can be challenging, especially for small-scale farmers. Factors such as climate, altitude, variety, and infrastructure can affect the suitability of each method. Moreover, different markets and buyers may prefer different processing methods, which can affect the marketability and price of the coffee.

Hanson Cheng

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