Are you roasting and brewing your own coffee? If yes, then, perhaps you wanna do a periodic check on quality. Wipe the table clean, turn on the light with a decent amount of brightness, unpack that bean of yours, sit and start inspecting the green beans one by one.
It is a long and hard work so I am suggesting you do it only once in a while. Check if your seller is paying attention to their quality control operations. Find another seller if found negative.
These were sorted out from one kilogram of green robusta beans. From what brand and source? It is a secret.
Black beans. Only four black beans! I felt amazed for a few seconds. The sorters were very attentive to black beans. They know very well of its bad affect to overall quality. Maybe it was a coincidence that this particular batch had very few black. The amount of next defect types ( as shown in the picture ) was telling me it was poorly sorted.
Cracked beans. The fault of coffee hulling machine and over-drying. Too low moisture content makes the bean brittle. It has a higher tendency to crack during hullling operation specially if the gap is set too close. There is nothing wrong with including cracked beans except for the fact that they roast faster contributing to unevenly roasted batch.
Insect damaged beans. I can tolerate these defects. They are hard too see. The inspector needs to look to every bean very thoroughly. Hold every bean, turn it around to see presence of holes. This slows down the selection process by more than ten folds.
Whole beans. Again, coffee huller fault. Hulls roast faster than beans and will surely get burnt before the beans are done. Burnt flavor!
Stones. These are unforgivable. These are foreign materials, not edible, and should not be part of. They are easily seen and therefore could be sorted out easily. Removing small stones is a lot easier by using sieves.
The beans I got is not of premium quality but it is still an export quality beans, based on the regulation “green robusta beans for export should not have more than 150 defects per 300 grams”.