Lactic acid fermentation enhances antioxidant potential of chicory by-products for functional food applications

Chicory ( Cichorium intybus ) processing generates substantial volumes of underutilized by-products, including peelings and roots, which are rich in polyphenols and other bioactive compounds with potential health benefits. This study explored the use of lactic acid fermentation as a sustainable strategy to valorize these residues into functional food ingredients. Eight strains of Lactiplantibacillus plantarum and Lactobacillus reuteri , including two isolates from the native Witloof chicory (Belgian endive) microbiota, were screened for their ability to ferment four types of chicory-derived by-products. Belgian endive peelings (EPBU) emerged as the most promising matrix based on bacterial growth, antioxidant potential, and hepatoprotective activity in ethanol-stressed hepatic cells. Antioxidant capacity was evaluated using both a biochemical assay (DPPH) and a cell-based ROS assay in hepatic and intestinal cell lines. While the DPPH assay confirmed the high baseline antioxidant activity of EPBU maceration, fermentation with strain 31c significantly enhanced cellular ROS scavenging, achieving up to a 17-fold reduction, among the more pronounced antioxidant enhancements observed for fermented plant-based matrices. Metabolomic analysis of fermented EPBU revealed the presence of chlorogenic acid and consistent elevation of compounds associated with fermentation pathways. These findings demonstrate the potential of lactic acid fermentation to improve the bioactivity of chicory by-products, supporting their use in sustainable food and nutraceutical applications. • Fermentation enhanced the antioxidant activity of endive peelings (EPBU). • LAB strains significantly reduced ROS in HepG2 and Caco-2 cells. • Fermentation mitigated ethanol-induced oxidative stress in HepG2 cells. • EPBU identified as a promising substrate for functional food applications.