Time-dependent changes in flavonoids, polysaccharides, and DPPH radical-scavenging activity during Lactiplantibacillus pentosus fermentation of Gardenia jasminoides

Plant-derived flavonoids and polysaccharides exhibit diverse bioactive properties, while their accessibility and functional performance can vary depending on molecular structure and interactions within the plant matrix. Lactic acid bacteria fermentation is widely used to enhance bioactivity, yet the dynamic relationships among polysaccharide degradation, flavonoid transformation, and antioxidant capacity are insufficiently understood, especially in Gardenia jasminoides systems. In this study, Lactiplantibacillus pentosus was used to ferment G. jasminoides flower extract under controlled conditions (28 °C, 24–60 h). Key parameters including pH, DPPH radical scavenging activity, total flavonoids, and total polysaccharides were monitored at 24, 30, 36, 42, 48, 54, and 60 h. The pH decreased rapidly from 4.2 to 3.57, indicating substantial acidification during fermentation. DPPH radical-scavenging activity showed a maximum relative increase of 31.64% at 36 h compared with the unfermented baseline, followed by lower values at later time points. Total flavonoid content reached its highest relative increase of 16.77% at 36 h and fluctuated thereafter, while total polysaccharide content showed an overall decrease with transient rebounds. Distinct time-dependent patterns were observed among total polysaccharides, total flavonoids, and DPPH radical-scavenging activity during fermentation. These findings indicate time-dependent associations among polysaccharide content, total flavonoid content, and DPPH radical-scavenging activity, with the highest DPPH response observed at 36 h under the tested conditions. This study provides time-resolved information on the fermentation-associated changes in G. jasminoides flower extract and may inform future evaluation of its potential functional applications.