Why is grading green coffee important? How to standardize the classification?
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Preserving the quality of green coffee is an important step in the supply chain. To do this well, the first thing is to classify green coffee beans. However, in each country, there will be different classification systems, processes, and terminology. This difference causes a lot of difficulties in communicating and comparing coffee quality when importing and exporting. So how to standardize the classification? Let’s find out with 43 Factory Coffee Roaster now!
The process of classifying green coffee beans
Although no system is considered standard or widely available, most classifications are based on similar core attributes. Coffee will be compared based on factors such as grain size, density, colour, appearance and the number of existing defects.
The first step in the grading process of green coffee is usually the size screening. Many farmers will use several filters with small round holes to separate beans of different sizes. The size of this hole is usually measured in 1/64 inch increments. For example, if the filter frame is 15 inches, the diameter of the hole is 15/64 inches (approximately 5.95 mm). Usually coffee beans will be somewhere between 12 – 19 inch filter frame size depending on variety and crop so farmers will have to consider based on the actual situation to choose the appropriate frames. In addition, some other farmers may opt for slotted filter frames to sort seeds by both width and length. Width is measured in 1/64 of an inch and length will be 3/4 of an inch. The most common slotted screen sizes used for green coffee grading are from 8 to 11.
Next, the coffee will be taken to the weighing table (or density sorter) to sort the beans. As in Kenya, manufacturers often adopt grading systems that use air to separate particles according to their density and then pass them through a color sorter. They will compare the colors on the grain surface to assess their quality. For example, green Arabica beans with a light green color are considered qualified. If the color fades or has an unusual color, the seeds are of poor quality, aging during storage. When going through all the stages from filter frame, density classification, color classification, … the coffee beans will go to the evaluation, scoring and then separating them into levels based on the total score achieved.
Why is green coffee classification important?
Coffee quality is the most important factor in the supply chain from producer to roaster. To ensure coffee quality, a green coffee bean grading process is required before storage. Classification of green coffee beans helps determine the size and density of the beans, two characteristics that affect the quality and the way the coffee is roasted. Large and dense coffee beans are usually of higher quality and need to be preserved more carefully to retain the best flavor.
Coffee grading also makes it easy for producers to market to buyers about the quality of their products, whether through auctions or other trading platforms.
In addition, the classification also tells the roaster the size and density of the coffee beans to adjust the roasting time and temperature accordingly. Coffee beans grown at higher altitudes are generally larger in size and density than beans at lower altitudes. Large coffee beans will take longer to roast than small beans. Therefore, in order to get a batch of evenly roasted and delicious coffee, you should choose batches of coffee with the same grade and know what their quality grade is.
In addition, the classification of green coffee also helps producers to detect and remove defective beans, adversely affecting coffee quality. Defects can appear due to environmental factors such as drought, heat, pests, or improper storage. Defective coffee beans often appear shriveled, deformed, void, black or black stripes. In particular, green coffee processed with contaminated water can cause unpleasant odors. Therefore, grading is an indispensable step to ensure the best quality of green coffee.
Why do countries use different grading systems for green coffee?
Each country will have a scoring system to classify green coffee, designed according to its own standard framework. There are several reasons for this:
The size and density of coffee beans in different countries due to the variety of varieties and methods of cultivation and processing. To maintain consistency within each country, separate classification systems must be used. For example, the Ethiopian classification system often uses small filters because it mainly grows wild heirloom coffee varieties with smaller grain sizes than other varieties. Or like Arabica producing countries need to have a different evaluation system from Robusta producing countries to ensure objectivity and accuracy for each type of coffee.
The language barrier is also the main reason for this difference. Each country will use a different language. Designing a common system using Portuguese or Vietnamese would be difficult for many farmers in Latin America or Africa.
How to standardize the classification of green coffee beans?
The lack of uniformity between the green coffee classification systems hinders the inspection and control of goods during the import and export process. The different grading system also makes it difficult to train. Adam S. Carpenter – an AST coach of the Specialty Coffee Association said that his students often get confused with multiple grading systems. Instructors also find it difficult to explain these systems in detail. Therefore, according to some coffee experts, there should be a unified classification system for specialty coffee to solve this situation.
So how to standardize the classification system? According to Adam, this is a big challenge because it is necessary to synthesize and adjust the evaluation standards so far of countries and translate them into languages around the world. In addition, to do this it is necessary to make a clearer distinction between the concepts of green coffee classification and sizing, and to use more unified language when talking about different types of green coffee, for example. like AA, A and AB.
Chuaga Kinuthia, a coffee technologist at Dedan Kimathi University in Kenya, said that in order to have a consistent classification system, it is important to standardize the process of assessing coffee bean size. Some roasters use different tools to measure bean size, so the quality of the roasted coffee can suffer if this information is not conveyed correctly. Therefore, it is necessary to have a general standard on particle size and then customize it for each locality.
However, Chuaga also said that in order to build a comprehensive system for countries, many factors need to be considered. This takes a lot of time and research. With the current conditions we can adjust the existing systems to make them more fair.
As can be seen, the classification of green coffee beans is an important step in the coffee processing process. Without it, it would be difficult for farmers to guarantee the quality of their coffee, and it would be difficult for roasters to roast coffee to the desired taste. But applying a standard system to all coffee origins is not easy. Today, each growing region still has their own distinct methods and terminology. This is likely to change in the future, but we don’t know for sure yet. If you want to know more, follow 43 Factory Coffee Roaster to update the news about world coffee!