Fermentation-Driven Valorization of a Carrot Juice By-Product into an Exopolysaccharide-Enriched Beverage

Carrot juice processing generates large amounts of pomace, a fibre-rich by-product with significant valorisation potential. This study explored the feasibility of fermenting carrot by-product with Levilactobacillus brevis AM7 and Leuconostoc pseudomesenteroides DSM20193 to produce exopolysaccharide (EPS)-enriched functional beverages. Beverages were fermented with or without sucrose addition (EPS⁺ and EPS^-, respectively) and characterized for microbiological, biochemical, rheological, and sensory attributes. Both strains showed robust growth (>8 log cfu/mL) and acidification (final pH below 4.8), comparable to plant-based yoghurt alternatives, with EPS synthesis markedly enhanced in sucrose-supplemented beverages. Leuc. pseudomesenteroides DSM20193 synthesized the highest EPS concentration (16.8 g/100 g dry weight), resulting in a 6-fold viscosity increase compared to EPS^- samples, thus improving the adherence to the spoon and preventing syneresis of the beverages. Sensory evaluation revealed that EPS⁺ carrot-based beverages had improved sweetness due to a slight sucrose residue, aroma, and mouthfeel, while maintaining low off-flavours and high colour uniformity. The results highlight carrot by-product as a promising substrate for developing clean-label beverages that are rich in dietary fibres and polyphenols and show antioxidant and potential prebiotic properties through sustainable fermentation processes.