Functional yacon juice fermented by <i>Lactiplantibacillus plantarum</i> QS7T: Chemical composition, flavor volatiles, and gut microbiota modulation

To prepare functional yacon juice, this study investigates the optimal fermentation duration, shelf-life, chemical composition, and flavor volatiles of yacon juice fermented by Lactiplantibacillus plantarum QS7T capable of utilizing fructo-oligosaccharides (FOS), along with its effects on gut microbiota. The optimal fermentation period was determined as 30 h, resulting in essential parameters: 3.46 g L^-1 for total acids and a viable lactic acid bacteria (LAB) count of 2.3 × 10⁸ CFU mL^-1. The predicted shelf life when stored at 4°C is 28 days. Throughout storage, the juice maintained significant FOS and viable LAB count (8.0 × 10⁷ CFU mL^-1). Total short-chain fatty acid significantly increased post-fermentation and storage, reaching 177.86 µg mL^-1. The total content and types of volatile components in yacon juice after fermentation by L. plantarum QS7T significantly increased, thus altering the flavor and improving the juice's appeal. Functional yacon juice also induced significant alterations in gut microbiota structure and abundance in mice, including increasing the abundance of beneficial microbes such as Firmicutes, Actinobacteriota, Faecalibaculum, Dubosiella, Bifidobacterium, and Akkermansia. These results indicate fermented yacon juice's potential as a functional food for gut microbiota modulation and anti-inflammatory benefits.