Extrusion-Induced Improvement Mechanism of Extraction Yield, Physicochemical Properties, and Antioxidant Activity of Platycodon Grandiflorum Polysaccharides.

This study aimed to elucidate the extrusion-induced improvement mechanism of the extraction yield, physicochemical properties, and antioxidant activity of Platycodon grandiflorum polysaccharides (PGP). The Platycodon grandiflorum powder was pretreated using a single-screw extruder to produce extrusion-extracted PGP (EX-PGP), which was then compared with polysaccharides obtained by hot water, ultrasound-assisted, and enzyme-assisted methods. Results showed that the extraction yield of EX-PGP was the highest (8.58%). Scanning electron microscopy (SEM) revealed substantial surface fragmentation and increased porosity of the extruded material. Size exclusion chromatography with multiangle laser light scattering (SEC-MALLS) indicated a marked reduction in molecular weight (5.44 kDa) after extrusion. EX-PGP exhibited enhanced antioxidant activity, with DPPH • $ \mathrm{DPPH}^{\bullet}$ and ABTS+ radical scavenging rates of 79.45% and 13.79%, respectively. Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) revealed a reduction in hydrogen bonding and crystallinity, while thermogravimetric analysis (TGA) showed improved thermal stability at higher temperatures. Overall, the study demonstrated that extrusion pretreatment is an effective and scalable processing strategy for the extraction of PGP, providing new insights for future research in the field.