May 19


The Anatomy of Green Coffee Beans: A Comprehensive Guide

By Hanson Cheng

May 19, 2023

Green coffee beans are the raw, unroasted seeds of the coffee plant. These beans are the fundamental ingredient in the production of one of the world’s most popular beverages: coffee. Although they are commonly known as “green,” they are not actually green in color, but ranging from pale yellow to light brown.

The anatomy of green coffee beans, which includes its structure, composition, and characteristics, plays a critical role in determining the unique flavors and aromas found in the final brewed cup of coffee. Understanding the anatomy of these beans is vital to coffee enthusiasts and industry professionals alike.

Understanding Green Coffee Beans

The definition of green coffee beans refers to the unroasted seeds of Coffea plants. These beans are essentially the raw form of coffee beans and are different in appearance, composition, and taste from the roasted coffee beans commonly consumed worldwide.

Green coffee beans have a greenish-brown color, which changes to dark brown during the roasting process. They contain a high percentage of caffeine and are rich in chlorogenic acid. Chlorogenic acid is a phytochemical that has been linked to several potential health benefits, such as reducing inflammation and aiding weight loss.

Green coffee beans are sourced from coffee plantations that grow Coffea plants primarily in tropical regions worldwide. These beans are harvested once the fruits of Coffea plants have matured and been separated from the tree. After the harvest, the green coffee beans are washed, dried, and then transported to roasters worldwide.

The unroasted green coffee beans are acidic, have an earthy flavor and a mild aroma. These beans are typically roasted to highlight their unique taste characteristics, which varies according to the geographic origin of the beans, the roasting techniques utilized, and the length of the roasting process.

Green coffee beans are becoming increasingly popular in recent years due to their potential health benefits and unique taste profile. Roasters and coffeehouses worldwide have begun incorporating green coffee bean extract into their products, including coffee-based energy drinks, supplements, and other beverages.

Their History

Green coffee beans are an essential component of the global coffee industry that has expanded rapidly in recent years. Despite this, the history of green coffee beans is often overlooked. The origin of green coffee beans can be traced back to the Ethiopian plateau, where the coffee tree first originated over 2,000 years ago.

Legend has it that a young goatherd, Kaldi, discovered the effects of coffee after noticing his goats’ excitement after consuming the red cherries from a coffee tree. Coffee’s popularity began to flourish in the Middle East, with Yemen being one of the first countries to cultivate and trade it. Coffee also spread across the Arabian Peninsula and eventually arrived in Europe in the 16th century.

The arrival of coffee in Europe sparked a surge in coffee houses, which became popular meeting places for intellectuals and artists. During the 17th century, the Dutch began to introduce coffee cultivation in their colonies, including Indonesia and Suriname. Coffee cultivation later expanded to Central and South America in the 18th and 19th centuries.

Today, green coffee beans are cultivated and harvested in over 50 countries worldwide, with Brazil being the leading producer. Understanding the rich history and evolution of green coffee beans is vital to appreciating the global coffee industry’s significance.

Cultivation of the green beans

Green coffee beans are grown in various regions around the world in countries such as Colombia, Ethiopia, and Indonesia. Cultivation plays a crucial role in producing high-quality green coffee beans, which are ultimately roasted to make coffee. During the cultivation process, several factors are essential to ensure successful growth and cultivation of the beans.

These include proper rainfall, temperature, and soil quality, which all contribute to the quality of the final product. The coffee plant is generally sown and grown in nurseries for a few months before being transplanted to its permanent location in a coffee plantation. Farmers need to care for the plants, providing regular watering and fertilizing to ensure they grow correctly.

Harvesting begins when the coffee cherries have reached peak ripeness, which can take up to nine months after planting. The beans are then harvested either through selective picking, where only the ripe cherries are picked, or strip picking, where all the cherries are removed from the tree regardless of their ripeness.

After harvesting, the beans must go through a process of washing or dry processing to remove the outer layers and pulp surrounding the coffee bean. From there, the green coffee beans are dried and sorted before being sold to roasters. As cultivating green coffee beans is a complex and delicate process, farmers must pay careful attention to each stage of development to ensure their beans produce high-quality coffee.

Physical Characteristics

Size and Shape

The size and shape of green coffee beans are crucial to the quality of the coffee they produce. Green coffee beans are typically small, ranging from about 5 to 7 millimeters in length and 4 millimeters in width. However, there are also slightly larger beans that can range up to 13 millimeters. The shape of green coffee beans is generally oval or round, but some varieties are more elongated, while others are more flat and oblong.

These variations in size and shape can impact how the beans roast and how they release their flavor during brewing. Oval-shaped beans tend to be denser and roast more uniformly, while round beans often require more attention to avoid over or under roasting. Similarly, flat and oblong beans may necessitate special attention during the roasting process, as they can roast unevenly.

An experienced roaster will know how to account for the size and shape of green coffee beans to achieve the desired taste and aroma. Size and shape can also impact the density of green coffee beans, which is an essential component of coffee quality. Denser beans tend to produce a richer, fuller-bodied coffee with a more prominent flavor profile.

They also tend to have a more consistent grind, which can improve the overall quality of the coffee. Understanding the variations in size and shape of green coffee beans is essential for coffee roasters and coffee aficionados alike, as it can significantly impact the final product.

Varying Color

The color of green coffee beans can vary depending on the region, climate, and altitude where they were grown. The most common color of green coffee beans is a pale green, resembling the color of an unripe grape. However, green coffee beans can also range in color from light yellow to various shades of green and even blue-green.

These color variations can be attributed to the levels of chlorophyll and carotenoids present in the beans. Chlorophyll is responsible for the green color, while carotenoids contribute to the yellow and orange hues. The intensity of the color can also be an indication of the quality of the coffee beans, with darker and more vibrant shades typically indicating better quality.

It’s important to note that the color of green coffee beans does not necessarily correlate with the level of roasting or the resulting flavor profile of the coffee. Understanding the color variations of green coffee beans is essential for coffee farmers, buyers, and roasters to ensure the best quality and flavor of the final product.

Density of the beans

The density of green coffee beans is an essential characteristic that plays a significant role in their overall quality. Density is a measure of the beans’ weight relative to their volume and is influenced by several factors, including altitude, soil composition, climate, and maturity level. In general, higher altitude locations produce denser beans, while the beans grown closer to sea level tend to be less dense. Additionally, the density of coffee beans varies depending on the cultivar; some varieties, such as Typica and Bourbon, tend to be denser than others like Catimor.

The density of green coffee beans is critical because it affects roasting and brewing. Denser beans absorb heat more slowly and evenly during the roasting process, which leads to a more consistent roast and flavor. In contrast, less dense beans may roast unevenly, leading to inconsistent flavors in the brewed coffee. The density of green coffee beans also affects their extraction during brewing. Denser beans tend to extract more slowly, producing a more complex and flavorful cup. Less dense beans may extract too quickly and produce a less complex and less flavorful cup.

Coffee industry professionals use various methods to measure the density of green coffee beans. One common method is to use a moisture balance to measure the moisture content of the beans. Because denser beans tend to have less moisture, this method can provide an indirect measure of the beans’ density. Another method is to use a densitometer, which uses X-rays to measure the beans’ density directly. This method provides a more precise measurement; however, it is more expensive and time-consuming.

The density of green coffee beans is an important physical characteristic that affects their quality, roasting, and brewing. It varies depending on several factors, including altitude, soil composition, climate, and cultivar. Industry professionals use various methods to measure the density of green coffee beans, including moisture balance and densitometer. Ultimately, understanding and controlling the density of green coffee beans is an essential aspect of producing high-quality coffee.

Chemical Composition

Caffeine Content

The caffeine content of green coffee beans varies depending on several factors, such as the plant species, harvest time, and processing method. Coffee plants belonging to the Coffea arabica species generally contain less caffeine than those of the Coffea robusta variety. Additionally, caffeine content tends to decrease as the coffee cherries mature.

As for processing methods, the wet process yields beans with lower caffeine content than those subjected to the dry process. Caffeine is a natural stimulant found in many plants, including coffee. It affects the central nervous system, enhances alertness, and reduces fatigue. The caffeine content in green coffee beans can range from about 0.8% to 2.5% of the bean’s weight.

This means that a cup of coffee can have between 15 and 120 milligrams of caffeine, depending on the type of coffee and the preparation method. However, caffeine content is not the only factor that affects coffee’s stimulant properties. Other substances, such as polyphenols and chlorogenic acids, also play a role in modulating caffeine’s effects and contribute to coffee’s overall health benefits.

Some of these benefits include reducing the risk of type 2 diabetes, Parkinson’s disease, and liver cancer. Understanding the caffeine content of green coffee beans is essential for coffee producers, roasters, and consumers alike. It helps to determine the coffee’s flavor profile, caffeine dosage, and potential health benefits. Additionally, it can guide decisions regarding coffee blends, roast types, and brewing methods. Finally, caffeine content can help consumers manage their coffee intake to avoid unwanted side effects, such as insomnia or anxiety.

Acidity in the green beans

Acidity is a critical component of the quality of green coffee beans. It refers to the tartness or sourness of the beans and can significantly impact the flavor profile of the final product. The pH level of green coffee beans ranges from 4.6 to 5.8, which is considered slightly acidic. Chlorogenic acids are the primary contributors to the sourness of green coffee beans.

They are naturally present in the beans, and their levels vary depending on the variety of the coffee plant and the growing conditions. Higher chlorogenic acid content in the beans typically results in a more acidic taste in the coffee. Acidity in green coffee beans can also vary depending on the processing methods used.

Wet-processed coffee beans tend to have higher acid content due to the fermentation process that occurs during production. On the other hand, dry-processed coffee beans have a lower acidity level because the fermentation process is minimal. The acidity level can also affect the caffeine content of the beans. Higher acid levels can lead to higher caffeine content in the beans.

Another critical factor that influences the acidity of green coffee beans is the roasting process. Roasting reduces the acidity of the beans as it breaks down chlorogenic acids. The lighter the roast, the higher the acidity level, and the darker the roast, the lower the acidity. However, over-roasting can result in a burnt taste, which negatively impacts the flavor profile.

Acidity in green coffee beans is a complex topic that significantly impacts the flavor profile and quality of coffee. Understanding the acidity levels can help coffee producers develop unique flavor profiles, and it can also guide consumers in choosing their preferred coffee type.

Flavor Compounds

The flavor profile of green coffee beans is influenced by a complex combination of chemical compounds. These compounds include alcohols, ketones, esters, and acids, which all contribute to the aroma and taste of the final cup of coffee. The most important flavor compounds in coffee are chlorogenic acids, which produce a bitter taste and are also responsible for the color of the beans.

Another important flavor compound is caffeine, which provides a bitter taste and also acts as a natural stimulant. In addition to chlorogenic acids and caffeine, a variety of other compounds contribute to the flavor of green coffee beans. For example, the organic acid content in coffee is significantly responsible for its perceived acidity.

Other factors that contribute to the flavor profile of coffee beans include roasting, brewing method, and storage conditions. Roasting can significantly alter the flavor of coffee, as it causes caramelization and Maillard reactions that create complex flavors. Brewing method also plays a significant role, affecting the extraction of flavor compounds from the beans.

The flavor of green coffee beans can also be influenced by environmental factors like climate, soil type, and altitude. Plants grown in higher altitudes generally produce beans with higher acidity and fruity flavors. On the other hand, beans grown at lower altitudes tend to have a more earthy flavor profile. Soil type and climate also play a significant role in determining flavor. For example, volcanic soil is rich in minerals and has been shown to produce high-quality beans with complex flavors.

The flavor of green coffee beans is influenced by a multitude of factors, including the chemical composition of the beans, processing methods, and environmental factors. Understanding the contribution of each of these factors is essential in achieving the desired flavor profile in a final cup of coffee.

Processing Methods

Wet Processing

Wet processing is a popular method of removing the outer layers of green coffee beans using water. This process involves several stages, including pulping, fermentation, washing, and drying. During the pulping stage, the outer layer of the coffee cherry is removed, revealing the mucilage-covered parchment layer.

The parchment layer must then be fermented to dissolve the mucilage and impart flavor to the beans. After fermentation, the beans are thoroughly washed to remove any remaining mucilage. Finally, the beans are dried to a specific moisture content. This method is valued for its ability to produce clean, bright, and fruity coffee with complex flavors.

However, wet processing can be more time-consuming, labor-intensive, and costly compared to other methods. Moreover, improper fermentation or over-fermentation can lead to off-flavors or defects in the beans. Therefore, wet-processing requires careful attention, expertise, and quality control to ensure consistent quality and flavor profile of the coffee beans.

Dry Processing

Dry processing is a method of removing the outer layers of green coffee beans using sun-drying. This process involves drying cherries on patios or raised beds, allowing the sun to naturally dry the coffee until the moisture content reaches around 11%. Once the cherries have dried to the right moisture level, they are then hulled to remove the outer layers and expose the green coffee beans. This method is commonly used in areas of the world where water is scarce or unpredictable.

Dry processing can have both advantages and disadvantages. On the positive side, it allows for the production of high-quality coffee with unique flavors and aromas that result from the natural fermentation that occurs during the drying process. Additionally, dry processing can be less expensive than wet processing since it requires less equipment and infrastructure. On the downside, it can be more difficult to control and maintain the quality of the coffee produced with this method, since there is a greater possibility of mold or other defects.

One challenge in dry processing is the need to consistently dry the coffee beans evenly. If the drying is not uniform, the coffee may develop off-flavors or experience uneven roasting during preparation. Additionally, exposure to direct sunlight during the drying process can cause the cherries to crack or split, which can damage the beans and affect their quality. For this reason, careful monitoring and management of the drying process is critical to producing high-quality dry-processed coffee.

Dry processing is used widely in many coffee-growing regions, including Brazil, Ethiopia, and Yemen, where it is known as the “natural” or “dry” method. This method has been employed for centuries and is still used today due to its affordability and the unique flavors it can produce. Though it requires careful attention and skill to produce high-quality coffee using this method, the results can be worth the effort.

Semi-Washed Processing

Semi-washed processing is a hybrid processing method that combines the aspects of both wet and dry processing methods. The process begins by harvesting ripe coffee fruits and then washing them using water to remove the outer skin of the fruit. After washing, the beans are left to dry for some time, usually for a few hours or overnight.

The beans are then put through a machine that removes the remaining fruit and mucilage by friction or through a gentle brushing action. This process prevents the beans from losing their natural flavors and characteristics, which is a common issue with dry processing. Semi-washed processing also reduces the water consumption required in wet processing.

The process is particularly popular in regions that have a limited supply of water or where the traditional wet processing method is not feasible. Although semi-washed processing is relatively new and has its limitations, it is an excellent option for businesses that require a balance between the flavors of dry-processed beans and the cleanliness of wet-processed beans.

Roasting Green Beans


The definition of roasting refers to the process of heating green coffee beans in order to transform them into roasted coffee beans. This process involves exposing the coffee beans to high temperatures, which causes chemical reactions to occur within the beans. One of the most significant effects of roasting is the development of flavor and aroma in the coffee beans.

Roasting also affects the color and texture of the beans, as well as their density and moisture content. The degree to which the beans are roasted can have a significant impact on their flavor and aroma profiles. Roasting can also affect the caffeine content of the coffee beans, as well as their acidity and body.

It is important for coffee roasters to carefully monitor the roasting process in order to achieve the desired flavor and aroma characteristics of their coffee blends. The art of coffee roasting involves a careful balance of heat, time, and technique in order to produce high-quality coffee that is flavorful, aromatic, and balanced in acidity and body.

Roast Levels

Roasting plays a vital role in determining the taste and aroma of coffee as it involves applying heat to the green coffee beans to change their chemical and physical characteristics. Roast levels refer to the degree of heat applied to the beans during the roasting process. There are several roast levels, including light, medium, and dark roast.

Light roast beans are heated to a temperature of around 356-401°F and are typically roasted for a short period. This results in a lighter-colored bean retaining more of its original flavor, with higher acidity and a milder taste. Medium roast beans are roasted at a temperature of around 410-428°F, and the process takes slightly longer than light roast. This results in a slightly darker-colored bean with less acidity than a light roast.

Medium roast coffee has a balance between the beans’ origin flavors and the roasting process’s effects. Dark roast beans are heated to a temperature of around 437-450°F, for a longer period, ranging from 12 to 16 minutes. The beans appear dark brown to black, and the roasting process improves the smoothness, sweetness, and full-bodied flavor of the coffee while reducing the original bean flavors. These beans are less acidic and have a bittersweet flavor.

Roasting Techniques

Roasting green coffee beans is a delicate process that requires skill and knowledge about the various techniques used to bring out the desired flavors and aromas. One of the most popular roasting techniques is the traditional drum roasting method, where the beans are placed in a rotating drum and heated by a gas-fired flame.

Another common method is hot air roasting, where the beans are roasted by hot air that circulates around them. This technique is known for producing cleaner and brighter flavors. Another technique is infrared roasting, which uses infrared technology to heat the beans. This technique is known for producing consistent and predictable roasts.

Roasting techniques have a significant impact on the chemical and physical changes that occur in green coffee beans during the roasting process. The roasting time and temperature affect the development of acids, sugars, and oils, ultimately affecting the flavor and aroma of the final product. Different techniques also bring out different flavor and aroma characteristics in the beans. For example, the slow and steady drum roasting method produces a more robust and full-bodied flavor, while the hot air roasting method produces a cleaner and brighter flavor profile.

Roasters must also consider the roast level they wish to achieve when selecting a roasting technique. The different levels of roasting, from light to dark, each have their own unique characteristics, and certain techniques lend themselves better to certain roast levels. For example, hot air roasting is often used to achieve a light roast, while drum roasting is used to achieve a medium to dark roast.

Understanding the different roasting techniques is essential for any coffee roaster looking to produce high-quality roasted coffee beans. Each technique has its own advantages and disadvantages, and the selection of the appropriate technique depends on the desired roast level and flavor profile. Roasters must also consider other variables, such as bean origin and processing, to achieve the best possible end result.


As our understanding of green coffee beans continues to grow, future research could focus on several critical areas. The first area of focus could be exploring the impact of different processing methods on the flavor profile of coffee beans. While wet processing is prevalent in many coffee-producing countries, dry processing is still used in some regions. Future research could seek to understand how processing methods affect the chemical and physical composition of coffee beans, which in turn impacts the taste of coffee.

Additionally, research could explore ways to reduce the carbon footprint of coffee production. The coffee industry is a significant contributor to greenhouse gas emissions, and finding ways to reduce the carbon footprint of coffee farming and production could have a significant positive impact. Finally, future research could explore the impact of climate change on coffee production. As global temperatures rise, weather patterns shift, and rainfall becomes more erratic, coffee production could be at risk.

Research could focus on developing new, more resilient coffee varieties that can adapt to changing climates, or on finding ways to mitigate the impact of climate change on coffee production. Understanding these critical areas could not only enhance our understanding of green coffee beans, but it could also lead to a more sustainable, environmentally friendly, and flavorful cup of coffee for future generations.

The anatomy of green coffee beans – FAQs

1. What is the anatomy of green coffee beans?

Green coffee beans are the unroasted seeds of the coffee plant. They consist of a hard outer layer called the exocarp, a fruity layer called the mesocarp, a parchment layer, a silver skin layer, and an endosperm or the actual coffee bean.

2. What is the role of the “parchment” layer in green coffee beans?

The parchment layer is responsible for protecting the coffee bean from external factors such as moisture and pests. It also ensures that the flavors and aroma of the coffee bean are preserved.

3. How does the “mesocarp” layer affect the flavor of green coffee beans?

The mesocarp layer or the fruity layer of the coffee bean has a significant impact on the flavor of the coffee bean. This layer contains a high amount of sugars, acids, and other compounds that contribute to the coffee’s flavor.

4. What is the “silver skin” layer in green coffee beans?

The silver skin is the thin, papery layer that covers the bean’s surface once the parchment is stripped off. It is made up of cellulose and hemicellulose and is responsible for protecting the coffee bean from drying out.

5. What is the primary function of the “endosperm” in green coffee beans?

The endosperm or the actual coffee bean is the part that gets roasted and brewed. Its primary function is to provide nutrients for the sprouting of the coffee plant. It is also responsible for the caffeine content, taste, and aroma of the coffee bean.

6. How does the “exocarp” layer protect green coffee beans?

The exocarp is the outermost layer of the coffee bean, and it serves as protection against physical damage and environmental factors. It is a tough layer that guards the other layers of the coffee bean and keeps them safe from moisture, heat, and pests.

Hanson Cheng

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