Extraction and biological activity of exopolysaccharide produced by Leuconostoc mesenteroides SN-8

An exopolysaccharide (EPS)-producing strain SN-8 isolated from Dajiang was identified as Leuconostoc mesenteroides. When sucrose was used as the carbon source for fermentation, the output of EPS was 2.42 g/L. High performance liquid chromatography analysis confirmed the presence of monomers such as glucan and mannose. The molecular weight detection value is 2.0 × 105 Da. Fourier transform infrared spectroscopy displayed the EPS had the basic skeleton and functional groups of a typical polysaccharide structure. Scanning electron microscopy showed smooth surfaces and compact structure. Thermal performance analysis showed that the highest heat resistance temperature of the EPS was 80 °C. Compared with vitamin C, its hydroxyl radical scavenging rate was as high as 32% and 1,1-diphenyl-2-picrylhydrazyl scavenging rate was as high as 40% under the same concentration. The peanut oil was the most emulsifiable at a concentration of 1.5 mg/mL, and the emulsification index was 0.55. These results might show that the EPS had high application value.