Effects of decoction time and Lactiplantibacillus plantarum fermentation on phenolic-related properties of Bidens pilosa leaf decoction and its residue

Bidens pilosa is rich in phenolic compounds, but the effects of decoction time and subsequent fermentation of the decoction and its residue remain unclear. This preliminary laboratory-scale study evaluated the effects of plant part and decoction time and examined Lactiplantibacillus plantarum fermentation of B. pilosa leaf decoction (BPLD) and its residue. Leaf decoctions showed the highest total phenolic content (TPC), total flavonoid content (TFC), and DPPH radical-scavenging capacity, with significant effects of plant part and decoction time. Submerged fermentation (SMF) was conducted with 0.5, 1.0, and 2.0% BPLD, and 1.0% BPLD was selected based on microbial growth. At the final sampling time, live L. plantarum treatments showed higher TPC, TFC, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) responses than the corresponding controls in both SMF and solid state fermentation (SSF). In SMF, inoculation significantly affected TPC, TFC, and DPPH responses, whereas fermentation time significantly affected TFC only. In SSF, viable counts increased during fermentation, and inoculation significantly affected TPC, TFC, and DPPH responses, whereas fermentation time significantly affected TPC and TFC. These findings provide preliminary laboratory-scale evidence that decoction time and L. plantarum fermentation were associated with changes in phenolic-related properties of B. pilosa -derived materials.