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Understanding Coffee Grading Systems

When it comes to preserving the quality of green coffee beans, there's an important step in the supply chain called grading. This process involves evaluating coffee beans based on various factors before they can be exported and enjoyed by coffee lovers around the world. However, there isn't a universal grading system in place. Different coffee-producing countries use their own methods and terms for grading green coffee. This diversity has led some experts to call for a simpler and standardized grading system that can be universally understood.

Today we will learn about this standardized grading system.

What Does Grading Assess?


While grading systems differ, they typically consider common attributes like bean size, density, color, physical appearance, and the presence of defects. Grading usually begins by sifting the green coffee beans through screens with different-sized holes. Each screen separates beans based on their size. For instance, a screen size of 15 means the holes are 15/64 inches in diameter, which is around 5.95 mm. Most green coffee beans fall within screen sizes 12 to 19.

Some systems use slotted screens with width measurements and a slot length of 3/4 inches (19 mm). Common slotted screen sizes for green coffee grading range from 8 to 11. Additionally, gravity tables or densitograders use air to separate beans based on their density.

Different countries have their own grading systems. In Kenya, for example, they use screen sizes like AA and AB to determine the quality, and then a different grade like TT or T based on bean density. Each region may have its own unique nuances in grading.


Why Do Countries Use Different Grading Systems?

Countries develop their own grading systems for several reasons. One major factor is that bean size and density can vary between regions. These differences make separate grading systems necessary to maintain consistency within each country's coffee production.

Language barriers also contribute to the variation. Brazil and Vietnam, two major coffee producers, have their own grading systems. Developing a universal system in Portuguese or Vietnamese could be challenging for farmers in Spanish-speaking Latin America and Africa.

Additionally, arabica and robusta coffee, the two main coffee species, require different grading criteria due to variations in bean size and processing methods.


The Call for Standardization

The differences in grading systems can create confusion, especially for those involved in the coffee industry. Some experts are advocating for a universally recognized grading system to simplify the process and ensure consistency.

Adam S. Carpenter, a coffee expert, highlights the challenges of these various systems, especially for training and communication. Standardizing bean size could be a starting point, helping roasters understand and blend coffee more effectively.


Grading Matters for Quality

Grading is crucial for maintaining coffee quality throughout the supply chain. It helps identify which coffees are denser or larger, characteristics often associated with higher quality. This information is essential for proper storage and communication between producers and buyers.

Roasters also rely on grading to determine roast time and temperature, as well as to achieve consistent roast profiles. Different grades of green coffee behave differently during roasting, depending on factors like bean density and size.

Defects in coffee beans can also be identified through grading, which is essential for overall quality control. Poor storage conditions or processing can lead to defects that affect the taste and aroma of coffee.


The Quest for Simplification

Given the complexity of existing grading systems, there's a growing need to simplify and standardize them. A universal grading system could benefit producers, farm workers, and roasters by making quality assessment easier and more consistent.

However, achieving such standardization is challenging due to historical practices, translations, and

regional differences. Some experts argue for maintaining current systems but adapting them to be fairer. Others believe that standardizing bean sizing and adopting clear language for grades could be a step in the right direction.

In the end, green coffee grading remains a crucial step in the journey from coffee farm to your cup. While standardization may be on the horizon, for now, each coffee-producing region will continue to use its own unique grading methods. The future of coffee grading systems remains an intriguing question for the coffee industry.

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