Effect of solution plasma process with hydrogen peroxide on the degradation of water-soluble polysaccharide from Auricularia auricula. II: Solution conformation and antioxidant activities in vitro

•Plasma with H2O2 was used to degrade Auricularia auricular polysaccharide (APP).•Higher H2O2 concentration, lower AAP concentration and narrower distance between the electrodes were favourable.•The flexibility of the conformation was improved.•The degraded AAP exhibited higher antioxidant activity. Synergistic degradation of water-soluble Auricularia auricula polysaccharide (AAP) by solution plasma process (SPP) in the presence of hydrogen peroxide (H2O2) was investigated. The effects of H2O2 concentration, AAP concentration and the distance between the electrodes on the degradation of AAP were evaluated. The results showed that higher H2O2 concentration, lower AAP concentration and narrower distance between the electrodes were favorable for the degradation effect. Particle size, congo red (CR), scanning electron micrographs (SEM) and atomic force microscopy (AFM) results confirmed that SPP irradiation with H2O2 improved significantly the flexibility of the conformation. The degraded AAPs exhibited greater metal chelating effects and DPPH radical scavenging effect than the original AAP. It concluded that the combined SPP/ H2O2 method could be used for preparation of low-molecular-weight AAP.