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Coffee Grades 101: Understanding Defects & Bean Quality

professional Q Grader preparing to test and inspecting the quality of coffee

Specialty coffee can be defined as beans that come from a specific climate in the world that are known for certain characteristics. But this is not the only way that the Specialty Coffee Association qualifies specialty coffee. It also has to be ethically sourced and sustainably farmed. This is usually the thing that is the hardest to judge as it requires eyes and ears on the ground.

Aside from climate of origin, whether the coffee is single origin or from multiple farms in one region within the microclimate, there is a way of determining the quality of cup that the coffee bean produces. This is what we know as coffee grade.

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What Does “Grade” Mean in Coffee?

Believe it or not, coffee grade is not solely determined by the resulting cup. Grade is a result of the relationship between the dried green coffee beans and the resulting cup. It is an exploration of the correlation between the percentage of defects or irregularities in a batch of green coffee and how it results once it is roasted. If the green coffee beans pass the initial inspection and meet certain criteria and the resulting beverage is of good quality, the grade will be better.

Robusta coffee bean with female hand
Image Credit: SAYASOUK, Shutterstock

How Is Green Coffee Graded?

The SCA has a standardized process for determining the grade of the green coffee beans using a sample of 350 grams.

Screening

The beans need to be screened to check for overall uniformity of size. Coffee bean screens have the same size holes ranging from 10/64 to 22/64 of an inch depending on the screen. The beans are sifted through a screen to find the overall average size. Specialty coffee cannot have more than 5% size variance among the 350-gram sample.

Primary Defects

The beans are laid out flat to be able to see each individual bean. The grading surface must be slick (for ease of movement), black, and at least 2 x 2 feet, laid out on a table of at least the same size. The lighting must be 4000 Kelvin (K) or higher to examine the beans. Those beans that look abnormal are set aside to be examined.

There are certain primary defects that if discovered cannot qualify the batch for being considered specialty coffee. According to the SCAA Defect Handbook, the primary defects are:

  • Full black (1)
  • Full sour (1)
  • Dried cherry/pod (1)
  • Fungus damage (1)
  • Foreign matter (1)
  • Severe insect damage (5 beans for a total of one primary defect)

If any of these defects are discovered, the coffee will automatically be disqualified for specialty coffee consideration.

green coffee beans in white background
Image Credit: coffeegeek, Pixabay

Secondary Defects

After the beans with primary defects (if any) are removed, then a more careful examination of the remaining beans follows. This will require more attention since secondary defects do not stand out as well as the primary defects. Small groups of beans (about 10 – 15 at a time) are separated from the rest of the 350 grams to be examined closely. To qualify as specialty coffee, a 350-gram sample of green coffee beans cannot include more than five secondary defects. The secondary defects according to the SCCA are:

  • Partial black (3)
  • Partial sour (3)
  • Parchment (5)
  • Floater (5)
  • Immature/unripe (5)
  • Withered (5)
  • Shell (5)
  • Broken/chipped/cut (5)
  • Hull/husk (5)
  • Slight insect damage (10)

The numbers in parentheses are the number of beans/occurrences of the defect that would constitute one (1) secondary defect.

Cupping

After roasting, the coffee will be tested for a certain flavor profile in accordance with farmer’s and the roaster’s intent. How well it matches the intentional flavor will determine if it is a higher or lower grade.

Professional coffee cupping
Image Credit: Benedict Kraus, Shutterstock

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What Are the Different Grades of Coffee?

There are essentially five different grades of coffee.

1. Specialty Grade

Specialty grade coffee beans can have zero primary defects and only 0-3 full secondary defects. This coffee can only vary in size of bean up to 5% of the entire sample. When roasted, the beans must be absent of what are called “quakers,” which are beans that are not ripe enough, are under-roasted, or both. Specialty grade coffee is considered the highest quality of coffee on the market. It results in a cup that is free of defects. In terms of flavor profile, the intended taste will come through onto the palate. The flavors that the farmer and roaster intended will be distinguishable.

2. Premium Grade

Overall, this is pretty quality coffee. It allows for up to eight (8) defects and three (3) quakers. The good news is that they are the same source of beans as specialty coffee. The main difference is that there’s greater tolerance for defects.

3. Exchange Grade

This grade has a higher tolerance for bean size variation. About half of the beans will be roughly a quarter-inch (15/64 inch, to be exact) and 5% of the beans will be smaller. After the roast, there can only be up to five (5) quakers per sample.

4. Below Standard Grade

This coffee has 24 to 86 defects per sample. It probably won’t be from a very good source either. It’ll work in a pinch but try to avoid coffee like this.

5. Off-Grade

Just stay away unless you like sour and bitter coffee. This coffee will have 86 defects or more per sample.

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Summary

If you are on a budget and can’t afford the absolute primo, cream of the crop coffee, it’s okay. Maybe you could splurge on that coffee for special occasions. But premium coffee should be reasonably affordable for someone who takes coffee seriously. Aside from quality in taste, coffee with a significant number of defects or coffee grown with pesticides might not be so great for your health.


Featured Image Credit: Gumpanat, Shutterstock

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Aaron Rice

Aaron is a Pacific Northwest native who enjoys coffee, playing guitar, and playing cribbage with his wife. He is currently a graduate student in Boston, Massachusetts.

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