Extraction, preliminary characterization and antioxidant properties of polysaccharides from the testa of Salicornia herbacea.

Response surface methodology and central composite design based on single-factor experiments were used to optimize the extraction parameters (i.e., extraction time, extraction temperature, and solid-liquid ratio) of polysaccharides from the testa of Salicornia herbacea (STP). The optimal conditions included a liquid-solid ratio of 57:1 (volume/mass), an extraction time of 300min and an extraction temperature of 87°C. Under these conditions, the maximal yield of crude STP was 1.30±0.06%, which agreed with model predictions. Preliminary characterization of the purified acidic polysaccharide (STP II-1) by high performance liquid chromatography indicated that it was composed mainly of d-mannose, d-rhamnose, d-glucose, d-galactose, d-arabinose, glucuronic acid and galacturonic acid. The antioxidant capacity of STP II-1 was analyzed by monitoring both the scavenging rate of the 2,2-diphenyl-1-picrylhydrazyl free radical and inhibition rate of H2O2-induced erythrocyte hemolysis.