The reasons for bad coffee can be very complex. Most problems arise long before the coffee reaches the consumer country. Possible reasons for poor green coffee:
Too many chemicals are used in cultivation, and the taste is transferred to the coffee cherries.
Poor harvest: Harvesting is done quickly and carelessly. Unripe cherries are mixed with ripe and already overripe & spoiled cherries.
Inadequate processing: Defects such as moldy cherries, insect-damaged coffee beans, etc., are not sorted out.
Careless processes: The processing areas of the finca are not kept clean, and old & spoiled residues constantly mix with the fresh coffee.
Faulty drying: If the green coffee is not dried properly or is mixed with other coffee during drying, mold develops due to the moisture.
There are even more possible reasons, and we have experienced them all ourselves on our finca. In the meantime, we have managed to improve all processes. However, many producers do not have this opportunity. For reasons of financial pressure, lack of knowledge, and lack of initiative. Why put in more effort when everything is paid the same anyway?
That's why it's important to know exactly where the coffee comes from. The insidious thing is that many problems with green coffee are no longer immediately apparent later on. So, if you don't know exactly where the coffee comes from and what exactly happened to it, you almost have to assume that inferiorly produced coffee is being blended in.
This leads us to problem number 2: Roasting. Since coffee is traditionally a mass product, the industry had to find a solution for the green coffee problems mentioned above.
Paying more for transparent origin and good coffee is, of course, out of the question...
So: Fast industrial roasting at extremely high temperatures. The result: Coffee that is almost burnt to mask all the flavor defects from the green coffee. Black on the outside, almost raw on the inside. Result: Bitter due to the excessively high temperatures, with chlorogenic acid that causes stomach problems due to the too-fast roasting, and a slightly rancid taste due to the poor raw material.