It is a coffee beloved by Hollywood and influencers – now researchers say they have found an ingredient that could help explain the unique flavour of kopi luwak.
Also known as civet coffee, kopi luwak is produced from coffee beans that have passed through the digestive system of the Asian palm civet. The resulting product is not only rare, but very expensive – costing about £130 for 500g.
It is also controversial, with animal welfare experts raising concerns that some producers keep civets in battery-style conditions.
Researchers say they have uncovered new clues as to the coffee’s unusual taste, revealing unroasted beans retrieved from civet poo have differences in their fat content to those from ripe coffee berries manually collected from trees.
“We believe that the way it is fermented in [the] gut make[s] the profile different,” said Dr Palatty Allesh Sinu, a co-author of the study from the Central University of Kerala, India. “The enzymes and microbiome involved in fermentation [in the civet] [are] different from [the] manual fermentation process.”
Writing in the journal Scientific Reports, Sinu and colleagues reported how, in January 2025, they collected beans both from wild civet scat as well as trees across five estates in Karnataka, India, that were cultivating robusta coffee.
The team then prepared and ground both groups of beans – although they did not roast them – before analysing them.
“When roasted, several heat-sensitive oils and esters can be degraded or changed their profile,” said Sinu.
While the team noted that some previous studies had found kopi luwak has a lower protein and caffeine content compared with traditional coffee – results experts have suggested is down to the beans passing through the civet’s gastrointestinal tract – no significant differences in protein or caffeine levels were found between the two groups of beans analysed in the new study.
However, the beans from civet poo did have a higher fat content, as well as higher levels of two fatty acid methyl esters – substances based on the building blocks of fats.
The team say the results could help explain the taste of kopi luwak.
“Fat and oils are essential ingredients of flavoured materials,” said Sinu, noting many volatile organic compounds – substances that help to give aroma and flavour – use fat as a medium or carrier.
Ramit Mitra, the first author of the study, said the two fatty acid-based substances were commonly used in the food industry as flavouring agents and were likely to impart a dairy-like flavour.
“Hence, we cannot rule out the possibility of these two compounds contributing to the taste profile,” he said.
The researchers note there are other important factors that affect the flavour of coffee.
“The core taste of coffee develops mainly from roasting and the chemical alterations that occur during that process. Our study focuses on examining the raw form,” said Mitra.
Dr Simon Maher, an associate professor in sensors and analytical instrumentation at the University of Liverpool, who was not involved in the work, said the study suggested the civet’s digestion tweaked the beans’ chemical profile.
“The civet-processed beans showed subtle differences, with higher fat content and more of certain fatty acids that might influence flavour, albeit the study was based on small samples of unroasted beans,” he said.
“Further research is needed to confirm how much of this survives roasting and shows up in sensory tests,” he added.
