How to recognize and
distinguish green coffee defects

Green coffee defects are beans where something on the farm, in the processing plant, or during transport negatively influenced the green bean. A green coffee defect results in an off-flavor, or it can even have a negative influence on your health. This green coffee defect poster helps you to recognize and distinguish the gnarly beans in a batch. From primary to secondary coffee defects.

How do you discover green coffee defects?

Q Graders (and other coffee quality professionals) discover green coffee defects in a process called green grading. Besides roasting and cupping coffee samples, Q Graders stare at the green beans, shift through the pile, and take out the defects. The number and equivalents of defects tell the Q Grader if the coffee grade and quality match the contract.

Is green grading difficult?

As first-time graders quickly find out, you need a good pair of experienced eyes, an amazing neutral light lamp, and a dark underground, if you do not want to be green grading the same lot for an hour. Not only can it be difficult to decide if a weird-looking coffee bean is defective, or just not mother nature’s most beautiful.

How many gnarly beans equivalate one green coffee defect?

Some defects weigh heavier than others. Such as black bean defects. They make a cup of coffee fermented, dirty, moldy, sour, or phenolic. And on top of that, black beans have a higher risk of Ochratoxins. Slight insect damage might influence roast consistency and so weighs less heavy. You need either 5 or 10 insect damage beans, depending on severity, to count 1 green coffee defect. Non-coffee beans (foreign material) also count as a coffee defect, as they might cause damage to your roasting equipment, and again, might pose a health issue.

Different coffee origins, different scales?

The number of equivalents to ‘one defect’ can differ per origin. Additionally, there are many different types of grades. Some coffee origins work with numbered grades (one, two, three, etc). But others work with letters or different preparation types (European prep vs. American prep), and so on. Many of them have different ‘equivalents to defect’.

And that is not all. Even when it looks the same on the label, it might be different. An Ethiopian grade one allows for fewer defects than an Indonesian grade one. Additionally, your trader might have set their own table of equivalents, where they agreed on a certain green grading standard with their suppliers. Confused yet?

Which coffee defects can you find in a coffee?

Here is a list of defects you may find in a coffee. Take note, the defect list you see is based on the Ethiopian defect and grading standard. Not the Indonesian standard.

Primary defects:

  • Full black
  • Full sour
  • Dried cherry/pod
  • Fungus damaged
  • Foreign matter
  • Severe insect damage

Secondary defects:                                                                                            

  1. Partial black
  2. Partial sour
  3. Parchment
  4. Floater
  5. Immature/unripe
  6. Withered
  7. Shell
  8. Broken/chipped/cut
  9. Hull/husk
  10. Slight insect damage

How do you prepare yourself?

There are several things you can do to tighten your quality control. First of all, know the preparation of your green coffee; what does the label say about the grade, and what does that mean? Although standards may differ from place to place, the Green Coffee Defect Handbook of the SCA is a very useful tool. Besides the handbook, our green coffee defect poster helps you to recognize and distinguish defects.

With these tools in hand, you will ace green grading and get a firm grip on quality control. So, now all you need to do is get a black background, a good lamp, set a timer to avoid green coffee staring, and off you go!