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Fermentation is a crucial part of coffee processing, and over the years researchers have shown how particular techniques can significantly improve coffee quality. In 2025, Brazilian scientists used self-induced anaerobic fermentation to bring underripe cherries up to specialty grade, while earlier this year Chinese researchers used a naturally occurring fungus to do the same with commodity-grade coffee.
The latest approach comes from researchers at the University of Jambi in Indonesia, who explored the possibilities of improving the quality of Liberica coffee. Lactiplantibacillus plantarum and Leuconostoc mesenteroides are bacteria often used in the fermentation of food products like sauerkraut, and are also found in the digestive tracts of civets. Civets are the animals that eat and digest coffee cherries to produce the highly sought after—and highly controversial—kopi luwak.
Using starter cultures obtained from Indonesia’s National Research and Innovation Agency, the researchers fermented Liberica beans anaerobically for either 48 or 72 hours, before processing and roasting them. The resulting samples included coffee fermented with each bacterium for both durations, as well as the two bacteria combined.
A trio of trained tasters from the Indonesian Coffee and Cacao Research Institute then assessed the samples using the Specialty Coffee Association’s 100-point cupping form. All the samples scored above the specialty floor of 80 points, compared with the control’s score of 77.71. The 72-hour co-fermentation using both bacteria earned a score of 87.57.
The researchers noted increased presence of phenolic compounds such as flavonoids and caffeic acid in the fermented samples, as well as a rise in antioxidant activity. Intriguingly, caffeine content decreased by a statistically significant amount in the fermented samples, especially in the sample that combined the two bacteria.
The researchers hope their findings can help develop a way to produce “artificial” civet coffee and, more broadly, improve the sensory quality of Liberica coffee.
Read the full story on the inoculated coffee here.
Photo courtesy of Nathan Dumlao on Unsplash.
