Ultrasound-driven co-culture fermentation enhances bioactive components, antioxidant activity and structural...

This study investigates the impact of multi-frequency ultrasound-assisted fermentation using Lactobacillus plantarum, Lactobacillus paracasei and Lactobacillus helveticus on the bioactive moieties composition, antioxidant assay and structural properties of Chinese yam (Dioscorea opposita Thunb). Ultrasound treatment improved microbial activity and mass transfer, promoting the release and biotransformation of bound phenolic components. As a result, total phenolic content increased from 689.36 to 8109.74 µg/mL, while total flavonoid content rose from 110.67 to 1158.48 µg/mL in the optimized treatment (CY₆). Antioxidant potential exhibited notable enhancement, with ferric reducing antioxidant power (FRAP) increasing from 651.60 to 1337.14 µmol/L and DPPH radical scavenging activity revealing a moderate increase (values expressed as % inhibition; calculation method specified). HPLC quantification presented substantial increases in key phenolics, such as quinic acid (228.94 to 2912.46 µg/mL) and catechin (25.58 to 66.62 µg/mL). Structural analysis (SEM and XRD) manifested reduced crystallinity and increased porosity, which may facilitate the release of bioactive components. Sensory profiling demonstrated improved flavor characteristics, particularly enhanced floral and fruity notes in fermented treatments. Overall, ultrasound-assisted LAB co-culture fermentation boosted the physicochemical and functional attributes of Chinese yam, suggesting its potential for development as a value-added functional ingredient.