Recommended Kenyan Coffee Brands and an Introduction to Coffee Bean Grading System

FrontStreet Coffee - Introduction to Kenyan Coffee Brands and Grading Systems

Kenyan coffee is renowned for its bright acidity, enchanting fruity sweetness and distinctive flavor profiles, making it a favorite among coffee enthusiasts. Among these, AA grade Kenyan coffee stands out for its exceptional quality and represents a prestigious brand within Kenyan coffee varieties. Kenya's AA grade coffee is classified based on bean size—let's explore this fascinating system!

Grading by Coffee Growing Altitude

This grading standard emerged primarily because coffee produced at higher altitudes generally exhibits superior quality compared to that grown at lower elevations. The combination of higher altitude and lower temperatures allows coffee to mature slowly, facilitating the accumulation of desirable compounds. Additionally, high-maturity green beans demonstrate excellent expansion during roasting, contributing to more consistent and stable quality.

Currently, coffee-producing countries that adopt this grading standard include Guatemala, Mexico, Honduras, El Salvador, and other Central and South American nations. Taking Guatemala as an example, the highest grade coffee is called SHB (Strictly Hard Bean), grown at altitudes above 1350 meters. This is followed by HB (Hard Bean) cultivated at 1200-1400 meters, SH (Semi Hard Bean), EPW (Extra Prime Washed), PW (Prime Washed), EGW (Extra Good Washed), and GW (Good Washed), each corresponding to specific altitude ranges: 1200 meters, approximately 1000 meters, approximately 800 meters, 600-800 meters, and below 600 meters respectively.

Grading by Screen Size

Some argue that bean size doesn't affect coffee flavor—for instance, Yemeni coffee features beans of varying sizes yet remains among the world's finest coffees. However, in many producing regions, coffee bean size serves as an extremely valuable indicator of quality. In these areas, large, full-bodied beans with beautiful curves indicate robust coffee growth and full maturity, allowing them to showcase their best flavor potential.

Furthermore, coffee beans of similar maturity levels exhibit consistent flavor profiles, contributing to quality coffee production. Consequently, most new world coffee farms employ this grading method.

This grading system utilizes various perforated screens for classification. Screens come in different specifications identified by numbers that correspond to their mesh hole sizes. Hole dimensions are calculated in units of 1/64 inch—if a screen's hole diameter measures 18/64 inch, it's designated as screen 18; if the diameter is 17/64 inch, it's screen 17. Following this pattern, screens with numbers 19, 16, 15, 14, and others exist.

The screening process involves placing coffee beans on screens and shaking them mechanically or by hand. Beans small enough to fall through the mesh holes are separated out and subsequently screened through smaller mesh sizes. Through this layered screening process, coffee beans are assigned their respective grades.

After grading, beans are classified into several levels: AA, A, B, C, and PB. AA represents the highest grade, with quality decreasing sequentially through A, B, and C. Beans below C grade are typically used for animal feed or fertilizer. Additionally, Peaberry beans, with their distinctive flavor and naturally smaller size, form their own category (PB) and typically command premium prices. We might also encounter X, Y1, Y2, and T grades—these coffee beans vary in size and contain many defects, making them inferior products not worth trying.

Regions commonly using this grading method include Kenya, New Guinea, Puerto Rico, Zimbabwe, Tanzania, and Uganda, where only AA grade and above qualify as specialty coffee. Additionally, many Brazilian coffees employ this system, though they directly indicate screen sizes (19, 18, 17...) rather than using AA, A, B, C classifications.

Grading by Screen Size and Defect Bean Ratio

Defective beans are a crucial factor that can compromise final coffee flavor. Therefore, removing defective beans represents a critical final step in green coffee processing. This leads to considerations about defect bean quantities, making the defect bean ratio, combined with screen size, another important grading method.

With the rise of specialty coffee trends, coffee-producing countries increasingly focus on quality control, with managing defective beans being one of the most important approaches. Consequently, using defect bean ratios as either a primary grading method or supplementary criteria has become increasingly common.

Currently, major countries employing defect bean ratio grading methods include Jamaica, Brazil, and Ethiopia. Jamaica utilizes a comprehensive evaluation standard combining region, altitude, screen size, and defect bean ratio. For example, Jamaica Blue Mountain No.1 refers to premium coffee beans from the Blue Mountain region, grown above 1700 meters, using screens 18/17, with a maximum defect ratio of 2%. The defect bean ratio serves as crucial evidence—Jamaica strictly controls defect bean percentages, with maximum ratios not exceeding 4% across all grades.

Brazil represents another unique case. As the world's largest coffee-producing country, Brazil faces significant grading challenges due to its massive production volume and numerous growing regions, making a single grading standard unsuitable. Consequently, Brazil employs multiple grading methods simultaneously, incorporating defect bean ratios, screen sizes, and cupping tests in its coffee bean grading process. While the first two methods need no further explanation, cupping testing represents one of the distinctive features of Brazilian coffee grading.

Knowledge Extension: Cupping Testing

Cupping testing involves evaluating green coffee beans that have been roasted, ground into powder, and steeped in hot water (approximately 94°C) to assess their aroma and flavor characteristics.

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