Optimization of fermentation conditions for enhancing the antioxidant activity of medicine and food homologous materials using <i>Lactobacillus plantarum</i>

Codonopsis radix, Astragalus membranaceus, Platycodon grandiflorus, and Tiger milk mushroom are promising candidates for functional food development. However, their limited bioavailability impedes a challenge to broader applications. In this study, fermentation of these medicine and food homologous (MFH) materials using Lactobacillus plantarum was optimized to enhance antioxidant activity. Through single-factor experiments and Pareto analysis, the key factors influencing DPPH radical scavenging activity, including the material-to-water ratio, sucrose concentration, and inoculum size, were identified. Response surface methodology and artificial neural networks were then employed to optimize fermentation parameters. The optimal conditions resulted in a DPPH radical scavenging rate of 95.8%. Furthermore, the levels of bioactive compounds, including polysaccharides, polyphenols, flavonoids, and saponins, were significantly elevated, which enhanced antioxidant activity and may have improved bioavailability. FTIR analysis confirmed the structural changes in the active compounds after fermentation. This study provides valuable insights into developing MFH-based probiotic fermented products, enhancing their nutritional and biological properties.