Improved Functions of Fermented Coffee by Lactic Acid Bacteria

Coffee is one of the most popular beverages in the world, and at present, specialty coffees are developing for better tastes, flavors, or functions. Fermented coffees also reflect this trend and some brands are commercialized. Unlike general fermented coffees, we tried to ferment coffee extract with several lactic acid bacteria. Finally, we selected three strains that persisted in the coffee extract, and show strong antimicrobial activity, for the fermentation starters. The strains were identified as Pediococcus pentosaceus (KNUT 0384), Lacticaseibacillus paracasei (CJNU 1840), and Lactiplantibacillus plantarum (CJNU 0441) based on 16S rRNA gene sequences. During the fermentation process, the total acidities (p < 0.05 vs. the control, non-fermented coffee extract) and cell masses increased, which indicates that the bacteria metabolized properly in the extract. Furthermore, the fermented coffee extracts showed increased antimicrobial activities against Listeria monocytogenes (p < 0.05 vs. the control) and Streptococcus mutans (p < 0.05 vs. the control), increased anti-oxidative activities (p < 0.05 vs. the control, except for the KNUT 0384 sample), decreased caffeine content (p < 0.05 vs. the control, except for the KNUT 0384 sample), and increased chlorogenic acid content (p < 0.05 vs. the control). Taken together, the fermented coffee extracts with the selected lactic acid bacteria could be specialty coffees where several functions are improved when compared with a control coffee extract.