Sumatran Coffee: Grading and Appearance

Oct. 18. 2019


The appearance of green coffee from Sumatra can be jarring, especially if you’re used to washed beans from Africa or Central America. Why, many ask, does a Grade 1 Sumatra lack uniformity of color and/or bean size? Why do we see more “ugly” beans in Indonesian green coffee? 


Let’s start by discussing a few terms – you can find more definitions in our Coffee Glossary


Grade: There is no universal grading scale for green coffee – in fact, nearly every country has its own grading scale. Grading can also be an unreliable measure of quality; sometimes a coffee earns a higher grade than it deserves, other times the grade is lowered to avoid tariffs. Grading in Sumatra is based on cup quality rather than appearance, so you can see a Grade 1 Sumatran coffee with up to 8% defects but high cupping scores. 


Appearance: Refers to the amount of defects in a particular coffee. We list appearance under the “Specs” portion of every coffee review. Our appearance rating is a little confusing but the gist of it is, the decimal number represents the amount of secondary defects found out of the 5 secondary defect allowance in “Specialty Grade” coffee.


Going with shells as our example, this 5 secondary defect allowance means we would technically allow up to 50 shell beans in 300 grams of coffee. If there were 30 shells, the calculation that goes into our Appearance category would be: 30 shells = 3 secondary defects; 3 (secondary defects) / 5 (allowance) = .6 defects per 300 grams. 


Defect: Refers to specific preparation problems with the green coffee, or a flavor problem found in the cupping process. Bad seeds in the green coffee sample are termed defects, and scored against the coffee to determine its grade. Roast problems sometimes produce defect flavors, as do poor sorting/preparation of the coffee, mistakes in transportation and storage, problems at the wet mill, bad picking of the fruit or problems going back to the tree itself.


Here’s what Dan, one of our coffee buyers, has to say about defects: 


Talking defects is so tricky because there’s nothing cut and dry about it. I feel like the term “defect” lends to an assumption that the coffee is bad, or at least tastes bad. The truth is there’s a whole range of defect types and the impact they have on the cup (if any) will vary. Coffee is produce and uniformity is a very hard thing to mitigate, especially since the size is so small. This doesn’t mean we don’t care how a coffee looks, because we do. But I think that when discussing defects as they are outlined in manuals such as the SCA handbook, it’s important to keep in mind that just because a coffee is not uniform and qualifies as a “defect” (I’m generally talking about secondary defects here), it doesn’t mean it tastes bad. Conversely, a terrible coffee can be nearly 100% defect free, have stable moisture, and even be a “good” cultivar like Caturra or Bourbon but cup very poorly. In short, visual judgement should never replace taste.


On culling, I do think it’s useful for picking out really nasty beans, but maybe not so important for every little broken, bug holed, or mis-shapen coffee. The majority of these are what are considered secondary defects and have a pretty high allowance when calculating grade number. And most importantly, they don’t really have an affect on flavor.”


Sumatran coffees are tricky in that they tend to be riddled with defects no matter what the grade. There are a few reasons for this, such as weather and processing method. That doesn’t mean they get a pass in our appearance count!  We receive a huge variety of unsolicited samples from producers in Indonesia, and it’s worth noting that most of the “Grade 1” coffee looks far worse than any coffee we ultimately purchase for resale. In his explanation of Giling Basah processing, common in Sumatra, Tom explains how we choose Sumatran coffees: 


“When Sweet Maria’s started back in ’97, right in the middle of this “specialty coffee as carbon-water” era, the samples of Sumatra coffees I looked at were hideous. And for perhaps a decade after that, many Indonesian coffees were exported with impunity, as “Grade 1 Mandheling” seemed to mean nothing, and 100+ physical defects per 350 gram sample of green beans was common. Indonesian exporters, perhaps as the most dubious in the coffee world, were not only given a free pass on the cupping table, but in terms of cleanliness of coffee preparation as well…It takes a lot of cupping and identifying a different set of reference points to determine what a really good wet-hulled Sumatra should be. In our lab we also check the defect count, ultra-violet appearance of the coffee, water activity, humidity, and density of the bean. These tell the story of the coffee, but ultimately we find that cupping reveals the truth just as well.


Our main takeaway? Don’t judge a book by its cover! If you’re taking a crack at roasting Sumatra or another Indonesian coffee, trust your palate over your eyes. If you do see something that seems amiss, don’t worry – feel free to email us a photo to [email protected] and we can take a look. For more information, check out our Sumatra Origin Page.



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