Updated: Apr 18, 2021
There are many factors that determine the quality of coffee, most factors are mainly based on the visual appearance of the coffee bean trough each step of its process and of course the flavor.
Let me explain. The physical defects can be observed at an early stage when the coffee bean is a coffee cherry. An example of a physical defect is the cherry being overripe. The coffee cherry is at its optimum sugar level and weight when it’s ripe. Once overripe and subsequently dried, it starts to lose weight and the sugar levels starts to diminish.
If the cherry has been a victim of a coffee pest such as the infamous Berry Borer, commonly known as “Broca” in Spanish, it will display tiny perforations which will have an impact on the flavor.
Once the skin and the pulp have been separated from the bean through the drying process, and the parchment layer is removed, the beans are inspected for other physical defects. For example, yellowish powder can be a sign of fungus caused by high humidity while in storage, fractured beans reflect a poor drying process or a faulty coffee huller.
There are other factors such as lack of water and nutrients that contribute to other physical defects and have a significant impact on the taste of the coffee. The humidity of a green coffee bean should be no less than 10% and no more than 12% humidity. It should smell dried and fresh These type of defects can be the reason for insipid and burnt flavors.
Coffee Beans Size. Also known a "Mallas" in Spanish.
Coffee beans are categorized/graded by their size on a scale of 12 to 18. Bigger beans tend to taste better because they are fully developed. The grading mechanism works as follows :
Premium : Over 18.
Supremo: Over 17.
Extra especial : Over 16.
Europa: Over 15.
Coffee in a scale of 14 is classified as Standard. Anything below is considered to be low quality and its classified as “Pasilla” with the exception of the coffee beans at scale 12 which are round and known as “caracol”.
Coffee beans are weighted before and after they are processed. If the difference is weight is higher than 20%, this is an indication that there is a high amount of small and hollow beans.