Coffee Grading & Classifications

Before any coffee is sold, it is classified by the number of defects, screen size, and cup quality. The defect count is aimed at giving a general idea of the quality of the cup. Two green-coffee classification methods are used: the SCAA green coffee classification, and the Brazilian/New York green coffee classification.

SCAA Method of Grading: 300 grams of properly hulled coffee beans are sorted, using screens 14, 15, 16, 17, and 18. The coffee beans remaining in each screen are weighed and the percentage is recorded. Since classifying 300 grams of coffee is very time-consuming, 100 grams of coffee are typically used. When dealing with a high grade coffee, with only a few defects, 300 grams can be used. If the coffee is of a lower quality with many defects, 100 grams will often suffice in a correct classification as either Below Standard Grade, or Off Grade. The coffees then must be roasted and cupped to evaluate cup characteristics.

The SCAA classification standard for green coffee beans is an excellent method for comparing coffee beans. It is superior over some systems in that it better accounts for the relationship between the defective coffee beans and the cup quality.

Specialty Grade Green Coffee
Specialty green coffee beans have no more than 5 full defects in 300 grams of coffee. No primary defects are allowed. A maximum of 5% above or below screen size indicated is tolerated. Specialty coffee must possess at least one distinctive attribute in the body, flavor, aroma, or acidity; it must be free of faults and taints. No quakers are permitted. Moisture content is between 9-13%.

Premium Coffee Grade
Premium coffee must have no more than 8 full defects in 300 grams. Primary defects are permitted. A maximum of 5% above or below screen size indicated is tolerated. It must possess at least one distinctive attribute in the body, flavor, aroma, or acidity, must be free of faults, and can contain only three quakers. Moisture content is between 9-13%.

Exchange Grade Coffee
Exchange grade coffee must have no more than 9 – 23 full defects in 300 grams. It must be 50% by weight above screen size 15 with no more than 5% of screen size below 14. No cup faults are permitted and a maximum of 5 quakers are allowed. Moisture content is between 9 – 13%.

Grading Coffee Beans Brazil/New York
In the Brazilian method, 300 grams of coffee are classified. The number of coffee beans equivalent to one full defect is given below. For example, a set of three shells counts as one full defect. On the other hand, one large rock counts as five full defects. If a coffee bean has more than one defect, the highest defect is counted. For example, a bean that is black and damaged by insects counts as one full defect due to its black attribute. Generally, coffee beans without defects, of the same origin, and that are similar in size, color, and shape, are classified as specialty green coffee beans. The coffee beans classification table is divided into two, since Brazilian legislation allows a maximum of 1% of foreign defects.

Coffee grading and classifications for both methods are defined by categories based on maximum number of defects in a 300g sample of green coffee. For example:
Extra fine category: Less than 15 defects.
Prime category: 15 – 30 defects.
Superior category: 30 – 60 defects.
Regular category: 60 – 120 defects.
Under no circumstances should the total number of defects exceed 120, in a 300g-sample.

Coffee Bean Classification

Coffee Beans by Size
Many countries classify and compare coffee beans by using a screen size sorting system. The theory behind this classification method is that coffees from the highest altitudes are more dense and larger in size than those from other altitudes. It is also accepted that coffees from higher altitudes have the best flavor profile, so there is a correlation between coffee bean size, density, and quality. However, this correlation has numerous exceptions and size classification should only be used to verify that the coffee lot is uniform in size, which helps insure a uniform roast.

The different coffee-growing regions have their own preferred terminology, but the best indicator of size is to know the screen size. The screen size is usually reported as 17/18, 15/16, 13/14, etc. This means 17/64 of an inch, 18/64 of an inch, etc.

There are 5 grades for green coffee standards determined by bean size:
Grade 0 : beans held back by screen No. 18 (7mm holes)
Grade I : beans passing through screen No. 18 and held back by screen No. 16 (6.3 mm holes)
Grade II : beans passing through screen No. 16 and held back by screen No. 14 (5.5 mm holes)
Grade III : beans passing through screen No. 14 and held back by screen No. 12 (4.7 mm holes)
Grade IV : beans passing through screen No. 12 and held back by screen No. 10 (4mm holes)

Coffee Grading Terms

AA
AA is a coffee grading term that refers to a specific, larger than normal, bean size. Kenya AA coffee beans, for example, pass through Grade 18 (18/64 diameter) sieve perforations, but are too large to pass through Grade 16 (16/64 diameter) sieve perforations. AA+ refers to coffee beans AA or larger. The term AA is used as a coffee quality (grade) due to the general correlation (with many exceptions) between coffee bean size and coffee flavor.

Altura
Altura means (height) in Spanish and is used to describe high grown, or mountain grown, coffee.

Excelso
Excelso is used mostly as a coffee grading term, especially in Colombia. Excelso coffee beans are large, but slightly smaller than Supremo coffee beans. Excelso coffee beans pass through Grade 16 (16/64 diameter) sieve perforations, but are too large to pass through Grade 14 (14/64 diameter) sieve perforations. The term (Excelso) is used as a coffee quality (grade) due to the general correlation (with many exceptions) between coffee bean size and coffee flavor. Colombia Supremo coffee beans are slightly larger than Excelso beans and will pass through Grade 18 (18/64 diameter) sieve perforations, but are too large to pass through Grade 16 perforations. Supremo and Excelso coffee beans may come from the same tree, but are sorted by size.

Hard Bean
Synonymous with high grown (HG),  refers to coffee grown at altitudes about 4,000 – 4,500 feet above sea level. Beans grown at high altitudes mature more slowly and grow to be harder and denser than beans grown at lower elevations. The inherent consistency and taste attributes of high grown beans makes them more desirable, and generally more expensive, than coffees grown at lower elevations.

Strictly Hard Bean
Synonymous with strictly high grown (SHG),  usually refers to coffee grown at altitudes higher than about 4,500 feet above sea level. Beans grown at high altitudes mature more slowly and are harder and denser than beans grown at lower elevations. The inherent consistency and taste attributes of high-grown beans make them more desirable, and generally more expensive, than coffees grown at lower elevations.

Strictly Soft Bean
Strictly Soft (SS) beans are grown at relatively low altitudes (under 4,000 feet). Beans grown at lower altitudes mature quickly and produce a lighter, less dense bean. Strictly Soft Arabica beans have a more rounded flavor compared to the generally more flavorful and dense Arabica beans grown at higher elevations.

Supremo
Used mostly as a coffee-grading term in Colombia. Supremo coffee beans are slightly larger than Excelso beans and will pass through Grade 18 (18/64 diameter) sieve perforations, but are too large to pass through Grade 16 perforations. Supremo and Excelso coffee beans may come from the same tree, but are sorted by size. Excelso coffee beans are also large, but slightly smaller than Supremo coffee beans. Excelso coffee beans will pass through Grade 16 (16/64 diameter) sieve perforations, but are too large to pass through Grade 14 (14/64 diameter) sieve perforations. The term (Supremo)is used as a coffee quality (grade) due to the general correlation between coffee bean size and coffee flavor.

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