Welcome to the weird and wonderful world of coffee grading. Like most things within the coffee industry, there is no internationally fixed way of grading coffee. Each coffee growing country generally grades its own coffee using its own grading system. These systems usually grade coffee based on the following:
• Growing region
• Bean type
• Any damage/ defects or inconsistencies.
• Processing method
• Plant variety and many more
We All Know Size Doesn’t Matter, Right?
Well, unfortunately when it comes to coffee, in many cases it does. Size is probably the most common way of grading coffee throughout the coffee world. Many countries grading systems are based on the size of the coffee beans. The most famous of these are probably Kenya, Colombia and a few other Central American countries. In these countries, the highest grade beans (AA in Kenya and Supremo in Columbia) are the biggest beans from the biggest screen sizes.
So How Are the Beans Sorted?
Once a coffee has been hulled it will be mechanically shaken through different sized screens/ sieves in order to separate the different grades/ sizes of beans. The screen sizes are normally 17/18, 15/16, 13/14, etc. This means 17/64 of an inch, 18/64 of an inch, etc.
Is Bigger Really Better?
Well in true diplomatic style yes and no. Usually larger and denser beans grow at higher altitudes. This is desirable because these coffees normally develop slower and have better taste profiles. Also, larger beans of a uniform size will roast more evenly giving the coffee greater consistency. However, if you grade purely on size then you will not take into account any defects that affect the coffee. For example you could have a batch of large Columbian beans that have been dried too quickly and are of poor quality; however without taking into account the defects they could still be graded as the highest grade.
Defects are very important in grading coffee. Lots of countries use a combination of size and the number of defects to grade their coffee. The specialist coffee association of America also uses this technique as its preferred method for grading coffee. This technique is far more efficient than just measuring the size and will help to ensure a higher quality coffee.
Defects are measured using a points system. For example, a black coffee bean in the sample counts as 1 defect. Also, 2 large rocks count as one defect; whereas 5 medium rocks will also, only count as one defect. Usually, a sample of 100-300g of coffee is taken and screened for size and checked for defects. The coffee is then given a screen size and graded by number as a result of the number of defects within the bag. Brazil also uses size and defects in its grading process but uses a slightly different system to score the number of defects within a sample.
Wouldn’t it be easier if everyone graded the same?
YES, it would make a lot of people’s lives within the coffee industry a lot easier. While efforts have been made by people like the SCAA to make this a reality, most coffee is still traded using the old grading systems from the country of production. Unfortunately, it is just a case of getting to learn the grading systems for each individual country and learning what quality and flavours to expect.
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