The evaluation and grading of green coffee beans is an important step in ensuring an excellent final cup of coffee. Only the finest quality coffee beans should be used for the preparation of extraordinary coffee drinks. Excellent roasting and brewing practices combined with poor-quality coffee beans will not create memorable coffee experiences.
Specialty coffee roasters usually display quality grading terms on the labels of their coffee bags. We may find grading terms such as Kenya – GUAMA AA. AA is a grading term defining a specific and large bean size. Other grading terms we might see on the label are SHB (Strictly Hard Bean) or SHG (Strictly High Grown).
There is no universal standard method for grading and classifying green coffee beans. Coffee growing countries have developed their own classification systems that are usually based on some, or all, of the following criteria:
- Botanical variety
- Preparation method (wet vs dry)
- Bean (screen) size
- Bean shape and colour
- Number of defects
- Permissible defects
- Bean density
- Cup quality
To ensure excellent roasting results, the beans also need to have a uniform size.
Green Coffee Beans Sizing Chart
The WS of the Coffee Research Organisation provides an international Green Coffee Beans Sizing Chart which displays how various coffee growing countries classify and compare coffee beans by using a screen size sorting system: here
The Challenge of Grading & Understanding
Sweet Maria’s (a Coffee Warehouse and Green Bean Supplier in Oakland, CA, USA) finds it very challenging that almost every country of origin has its own grading scale: ‘It can be incredibly confusing. Sometimes the coffee earns a higher grade than it deserves, sometimes the grade is actually lowered to avoid tariffs! Central and South Americans tend to follow the SHB and SHG model (Strictly Hard Bean and Strictly High Grown indicates altitudes above 1000m). So hard beans grow at higher altitude and that’s good, right? Well, in Brazil’s grading, Strictly Soft is a top grade. Many countries use a simple numeric scale. But a Grade 4 Ethiopian is the top Dry-Processed grade you’ll see (Gr.2 in washed Ethiopians), and a Grade 1 Sumatra DP allows 8% defects (in fact Sumatra Grading is based on cup quality)! In essence, all should conform to the Green Coffee Classification System, but they don’t.’ See: here