Why does specialty coffee taste like potatoes?

Unlike regular coffee, specialty coffee is a lot like wine: mouthfeel and flavor and smell are everything.

Potato Taste Defects (PTD) is defined as a quality defect/flaw. Many people believe that potato taste first appeared in coffee produced in Rwanda, an East African country. This defective taste makes the coffee quality lower and seriously discourages international buyers from purchasing Rwandan coffee.

Potato flavor

"It has a musty smell that reminds me of old cardboard," notes Thomas Miller, of the University of California. "To me, it tastes like toenails."

Coffee Taster

SCA flavor wheel (defective part)

The relevant scientific experiment (Gas Chromatography-Mass Spectrometry) analyzed the volatile compounds in the potato odor. The main component analysis of the chromatographic data showed: tridecane, dodecane, tetradecane, 3-isopropyl-2-methoxypyrazine (IPMP).

What causes potato flavor?

The potato flavor is unique to East Africa, and it may be related to the volcanic soil, or it may be caused by the unique complex insect composition here. Thomas Miller, an entomologist at the University of California, pointed out: "The potato flavor is related to a local stink bug called antestia. These insects are generally present in the producing areas of potato-flavored coffee. These insects live in abandoned coffee plantations or in the mulch under banana trees. This insect can destroy coffee yields by up to 35%."

The dried antestia powder was analyzed by GCMS, and the volatiles found in the potato odor analysis were also found. In addition, the coffee with obvious insect damage on the surface also showed IPMP in the internal volatile analysis.

I have a very strange question. I am familiar with the taste of potatoes, but what do toenails smell like?

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