Eexopolysaccharide production of Pantoea sp. BCCS 001 GH: Physical characterizations, emulsification, and antioxidant...

The newly discovered exopolysaccharide (EPS) produced by Pantoea sp. BCCS 001 GH, isolated from nectarine fruit and some of its physical properties were characterized. This paper examines precipitation, rheological behavior, emulsification, and antioxidant activities of EPS. Particularly, the concentration of common salt (NaCl) affected on precipitation of EPS; while the low ratio (3 V_agent/V) of CaCl₂ isopropanol to culture broth was required. The Zeta potential value of emulsified particles had a high surface charge -65.67 ± 0.6 mV. The strong hydrogen bonds and/or hydrophobic interactions between the polysaccharide and the Congo red molecule showed the triple helical polysaccharide. The water solubility index and water holding capacity of the EPS were 15.6 ± 0.22, 662 ± 12.5%, respectively. The degradation temperature (Td) of 318 °C was observed from the TGA curve for the EPS. The rheological study indicated that the EPS had typically non-Newtonian pseudoplastic behavior. Among the EPS and Tween 80 tested against oils/hydrocarbons, EPS was found to be one the most effective emulsifying agent against kerosene, xylene, hexane and diesel (72.8, 74.5, 68.3 and 81.1%, respectively). It was found that changes in pH (2-12) significantly influenced the emulsification of kerosene and diesel. In vitro antioxidant activity of EPS against hydroxyl, 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH), and superoxide free radicals shown good antioxidant activities. These results indicate the favorable potential of the EPS from strain BCCS 001 GH in food and pharmaceutical fields.