Characterization of exopolysaccharide produced by Lactobacillus kefiranofaciens ZW3 isolated from Tibet kefir – Part II

ZW3 is a newly discovered exopolysaccharide (EPS) produced by Lactobacillus kefiranofaciens ZW3, isolated from Tibet kefir. Some of its properties have been characterized in our previous paper. Present research demonstrates some other important aspects of this EPS. The molecular weight obtained by gel permeation HPLC was 5.5 × 104 Da. Solubility, water holding and oil binding capacity of ZW3 EPS were 14.2%, 496.0%, and 884.74% respectively. Scanning electron microscopy (SEM) of ZW3 EPS demonstrated a smooth surface with compact structures. A topographical examination of EPS by atomic force microscopy (AFM) revealed that ZW3 EPS is composed of almost uniform net of molecules. Rheological study indicated that common salt did not affect the viscous behavior of ZW3 EPS and acidic pH may enhance its viscosity. Exopolymer showed a melting point of 93.38 °C. A degradation temperature (Td) of 299.62 °C was observed from the TGA curve for the polysaccharide ZW3.