Defects or, more precisely, “coffee defect” is an unpleasant characteristic/feeling in taste (negative). Causes may be careless processing of green coffee beans, improper harvesting, inappropriate humidity during storage or insects, etc.
Green coffee beans can also contain physical imperfections and defects such as hollow, porous, chipped deformation, underripe or blackened beans, foul, moldy, or roasted beans affected by insects and animals’ invasive harm.
Most defects can be detected and eliminated during the grading process. Some areas only perform defect removal by hand, while others use UV lamps and LED classifiers. But even modern technology currently cannot capture everything. For example, potato taste defect is widespread in Rwandan and Burundian coffee and is nearly undetectable until the coffee is extracted with an odor resembling a raw potato.