Potato taste defect (PTD)

A primary defect commonly traced to Central Africa’s Great Lakes region (namely near Lake Kivu) that describes an off-flavor impacting coffee quality. It is most often found in coffees from Rwanda, Burundi, the Democratic Republic of Congo, and Uganda. Studies have found that this defect is caused by a naturally occurring chemical called 2-isopropyl 3-methoxy pyrazine (IPMP). In certain coffee beans, IPMP is present at much higher concentrations, producing an aroma and taste of raw potato. Though studied in coffee since the 1950s, there is no clear reason as to why it happens. Since potato defect causes random coffee beans to smell and taste like peeled potato, any single bean ground with others can spoil a brewed batch. It’s important to smell the coffee before you grind or serve, grind or brew in smaller amounts, and discard if you sense any coffee with the potato defect.