Submerged Fermentation With Three Lactic Acid Bacteria Improves the Flavor of Green Coffee Beans

Lactiplantibacillus plantarum, Lacticaseibacillus paracasei , and Weissella confusa are lactic acid bacteria found in the intestines of the Luwak , potentially contributing to the fermentation process that enhances coffee flavor. This study aimed to evaluate the effects of these bacteria on the flavor profile of green coffee beans and to identify key flavor‐related compounds. Green coffee beans were fermented for 24 h at 37°C using L. plantarum strain QS029, L. paracasei strain FN037, and W. confusa strain FN015. Cup testing indicated that fermentation with QS029 ( p < 0.05) and FN015 ( p < 0.01) significantly enhanced the sweetness and body of the coffee compared to the unfermented control. Gas chromatography–mass spectrometry analysis revealed that QS029 fermentation produced characteristic aroma compounds, for example, 2,6‐dimethylpyrazine, benzeneacetaldehyde, and 2,6‐diethylpyrazine, whereas FN015 fermentation led to the generation of 1‐phenylethanol, acetic acid, and 2‐isoamyl‐6‐methylpyrazine. Liquid chromatography–mass spectrometry analysis showed that caffeine levels exhibited a downward trend across all three bacterial treatments. Notably, trigonelline levels decreased only in the FN015‐treated samples, while chlorogenic acid levels increased exclusively in the QS029‐treated coffee beans. These findings highlighted the strain‐specific modulation of flavor and bioactive compounds in coffee during fermentation and may contribute to the development of fermented coffee products with flavor profiles reminiscent of Kopi Luwak .