Physicochemical properties and antioxidant activities of polysaccharides sequentially extracted from peony seed dreg

• Four sequential extractions of peony seed dreg polysaccharides (PSDP) showed the characteristic absorptions of polysaccharide, but also displayed some slight differences.
• HBSS with the highest emulsifying activity and CHSS with the longest emulsifying stability.
• CASS showed highest abilities in the DPPH radical scavenging activity, reducing power and ABTS radical scavenging activity.

The sequential extraction of peony seed dreg polysaccharides (PSDP) with hot buffer (HBSS), chelating agent (CHSS), dilute alkaline (DASS) and concentrated alkaline (CASS) yielded four different polysaccharide fractions. Based on their absorptions at 3600–3200 cm−1 and 1200–800 cm−1, these fractions were confirmed to be polysaccharides. The properties of four PSDPs displayed some slight differences. The CASS showed the highest peak temperature and endothermic enthalpy. The emulsifying activity and emulsifying stability of four PSDPs exhibited a dose-dependent pattern; HBSS showed the highest emulsifying activity, and CHSS displayed the longest emulsifying stability. The four PSDPs also exhibited wide variations in their antioxidant activities. For example, i) CASS showed the highest DPPH radical scavenging activity, reducing power and ABTS radical scavenging activity; ii) HBSS exhibited the highest hydroxyl radical scavenging activity, and iii) CHSS displayed the higher ferrous ions chelating ability than others.