Fermentation of black wolfberry juice using a mixed culture and compound substrate: screening of lactic acid bacteria, process optimization, and quality analysis

Background This study aimed to enhance the quality of black wolfberry juice through fermentation with mixed lactic acid bacteria (LAB) and a composite substrate. Methods Optimization identified a synergistic blend of Lactobacillus rhamnosus GG, Lactobacillus delbrueckii subsp . bulgaricus , and Lacticaseibacillus casei , along with a substrate consisting of black wolfberry, Potentilla anserina , and isomalto-oligosaccharide. Results Compared with unfermented juice, this process significantly increased total sugar and total phenolic contents by 45.16% and 43.96%, respectively, and markedly boosted antioxidant activity, with DPPH and ABTS + radical scavenging rates improving by 48.58% and 59.47%, respectively. Multi-omics analysis revealed significant positive associations between the relative abundance of Lactiplantibacillus plantarum and specific flavor-related metabolites as well as lipid profiles, and led to distinct remodeling of lipid and triterpenoid profiles. Conclusion The multi-omics integration systematically elucidated the potential metabolic pathways underlying the quality improvement, thus providing a theoretical reference for laboratory-scale process optimization of fermented black wolfberry juice.