Extraction and physicochemical properties of Polygonatum sibiricum polysaccharide and preparation of freeze-dried coffee

Antioxidative polysaccharides are widely developed in various industries. Herein Polygonatum sibiricum polysaccharides (PSP) was prepared by water extraction and alcohol precipitation. Multiple characterizations on physicochemical properties and structures showed that the pale-yellow PSP powder contained 71.97% total sugar and galactose was its primary monosaccharide constituent. Fourier-transform infrared (FT-IR) spectroscopy identified typical polysaccharide characteristic peaks and scanning electron microscopy (SEM) displayed its loose porous microstructure. PSP were mixed with coffee raw materials to manufacture Polygonatum sibiricum polysaccharide freeze-dried coffee (PSP-FDC) with favorable solubility sensory performance and antioxidant capacity. In vitro radical scavenging tests proved PSP-FDC exerted dose-dependent DPPH and hydroxyl radical elimination effects and the maximum scavenging rates reached 86.38% ± 0.88% and 57.44% ± 0.70% at 4 mg/mL. In vivo tests on Caenorhabditis elegans ( C. elegans ) indicated that PSP-FDC extended nematode lifespan enhanced superoxide dismutase (SOD) and catalase (CAT) activities and decreased malondialdehyde (MDA) accumulation against oxidation damage.