Before green coffee beans reach our hands, they often go through many stages, during which defects are almost unavoidable. Some defects are obvious at the green bean stage, yet once roasted they may be cleverly masked. The SCAA (Specialty Coffee Association of America) has established strict grading standards for specialty Arabica coffee, covering defect types, moisture content, odor, bean size, and more. This article will systematically outline the SCAA's defect classification rules and scoring requirements, explain in detail the causes of various defective beans and their impact on cupping flavor, and help enthusiasts develop a sharp eye for identifying specialty coffee. At the same time, the article retains relevant recommendations from the Front Street brand for readers' reference.
You love coffee, but perhaps you are not aware that green coffee beans actually harbor all kinds of defects, numerous and even rather bizarre. These defects come from a wide variety of sources, may interfere with our perception of coffee flavor at different levels, and may also affect health. However, many defects that are easily identifiable at the green bean stage quickly become hidden once roasted. So the roasted coffee beans we usually see mostly have a uniform appearance and consistent color, presenting a beautiful coffee brown, and after being blended with milk and various flavored syrups, their original flavor characteristics are often largely masked.
Coffee is, after all, an agricultural crop. From sowing, cultivation, picking, processing, storage, roasting, to preservation and brewing, it must travel a long and arduous journey before reaching our cup and adding flavor to life. It truly does not come easily. The appearance of defects large and small is normal; it is only a matter of how many there are. And those beans that aspire to become specialty coffee must pass through layer after layer of screening, with every single one needing careful handling and serious attention. Next, let us look together at the SCAA (Specialty Coffee Association of America) grading requirements for specialty Arabica coffee. After reading this article, you will be able to develop a sharp eye, understand the ins and outs of specialty coffee thoroughly, and also appreciate why so many coffee professionals devote great effort to improving coffee quality and advancing specialty coffee.
[Defect Subcategories] (350g green beans)
The SCAA Arabica grading standards (refer to the table above) divide green coffee bean defects into Category 1 defects and Category 2 defects according to their degree of impact on coffee quality. Under these two major categories there are different specific defects, and each type of defective bean has a corresponding number of beans that converts to a full defect. Therefore, after counting the quantity of each type of defect, it must be converted into full defect equivalents. For example: among Category 1 defects, 1 full black bean counts as 1 unit of Category 1 defect; 5 severe insect-damaged beans also count as 1 unit of Category 1 defect (when fewer than 5 or 6 beans, it is also recorded as one unit of Category 1 defect). Among Category 2 defects, 3 partial black beans count as 1 defect; 10 slight insect-damaged beans also count as 1 defect.
Specialty coffee is required to meet:
In a 350g sample, not even 1 unit of Category 1 defect is allowed, and Category 2 defects must not exceed 5.
In a 100g sample, it is required to contain no quakers.
[Moisture Content]
Washed beans: 10%~12%
Natural beans: 10%~13%
[Green Bean Odor]
Must not have abnormal odors.
[Green Bean Size]
On the basis of the size specified in the contract, the variation is less than 5%.
Note: If multiple defects are found on the same coffee bean, the type of defect with the greatest impact on cupping quality is selected for scoring.
Below is an introduction to each type of defective bean one by one.
[Full Black Bean/Partial Black Bean]
Definition: Green beans that are completely black inside or on the outer surface, appearing opaque black.
Cause: Excessive fermentation caused by microorganisms.
Cupping performance: fermented or stinker flavor, dirty flavor, sharp acidity, musty flavor, phenolic flavor.
[Full Sour Bean/Partial Sour Bean]
Definition: Fermented green beans that are overall pale yellow or reddish brown.
Cause: Infection by microorganisms during harvesting and processing, leading to fermentation. Specific causes may include: picking overripe coffee cherries or coffee cherries that have fallen to the ground; contamination by water during processing; or coffee cherries hanging on the tree in a wet state and over-fermenting.
Cupping performance: Depending on the degree of fermentation, stinker flavor, sharp acidity, or fermented flavor may occur.
[Mold Infection]
Definition: Green beans that are yellow or reddish brown due to mold.
Cause: From harvesting to storage, temperature and humidity conditions are suitable for mold growth.
Cupping performance: May produce fermented flavor, musty flavor, dirty flavor, phenolic flavor.
[Foreign Matter]
Definition: Foreign objects other than coffee, such as stones or twigs.
Cause: May appear at any stage of green bean processing.
Cupping performance: Makes the coffee taste off.
[Dried Coffee Cherry Pod]
Definition: Green beans partially or completely wrapped in black fruit skin.
Cause: Incomplete removal of pulp during the washed bean process, or incomplete removal of floating matter during initial water separation; natural beans not properly handled during hulling or sorting.
Cupping performance: Fermented, musty, phenolic flavor.
[Severe Insect-Damaged Bean/Slight Insect-Damaged Bean]
Definition: Green beans bitten by insects with fewer than 3 holes (slight insect-damaged bean) or more than 3 holes (severe insect-damaged bean) of 0.3~1.5mm diameter.
Cause: Mainly affected by the coffee berry borer beetle.
Cupping performance: Affects the appearance of roasted beans, and may bring dirty flavor, Rio flavor, or musty flavor.
[Broken Bean]
Definition: Broken green beans or fragments of green beans.
Cause: Improper machine adjustment during green bean processing and pulping.
Cupping performance: Earthy flavor, dirty flavor, sharp acidity, fermented.
[Unripe Bean]
Definition: Silver skin firmly attached to the surface of the green bean, with a sunken body, smaller size, pointed ends, and a slightly boat-like shape.
Cause: Harvested in an immature state.
Cupping performance: Grassy flavor, straw flavor, green astringency; it is the main source of astringency in coffee.
[Shriveled Bean]
Definition: Green beans that are wrinkled like raisins, small in size, and deformed.
Cause: Insufficient water supply and excessive sunlight during development.
Cupping performance: Grassy flavor, straw flavor.
[Shell Bean]
Definition: Deformed green beans shaped like a shell or ear with thin skin.
Cause: Genetics.
Cupping performance: Scorched flavor.
[Floater Bean]
Definition: Green beans that are whitish or faded and float on water because they are light in body.
Cause: Improper storage or drying treatment. Parchment beans left in corners of a dryer or drying rack form faded, low-density beans; or parchment beans stored in a high-humidity environment.
Cupping performance: May produce fermented, grassy, straw, earthy, or musty flavors, and may also dilute the flavor without making the coffee taste off.
[Parchment Bean]
Definition: Green beans completely or partially wrapped in dried parchment.
Cause: Improper machine calibration during processing.
[Bean Husk]
Definition: Dark fragments of dried fruit pulp attached.
Cause: Not cleaned thoroughly during natural bean processing, or improper calibration of the pulping machine.
Cupping performance: Can bring dirty flavor, earthy flavor, musty flavor, fermented flavor, phenolic flavor.
[Quaker]
Not fully roasted, lighter in color than other roasted coffee beans.
Well, are you frightened by these defects? Then remember to choose specialty coffee!
Compiled by: xuwen
Reference: 《SCAA Arabica Green Coffee Defect Handbook》
The above content is reprinted from "Mingqian Coffee". Thanks are expressed here!!
The above content is compiled by CoffeeHunters, a coffee news website.
