characterization of the dextran produced by leuconostoc mesenteroides from date fruit extract

in the present study, the production of dextran from date extract and sucrose as carbon sources by the bacterium leuconostoc mesenteroides nrrl b512 (f) was investigated. in comparison to blue dextran (mw≈2000 da), dextran molecular weight was reduced (mw2000 kda). flow behavior indices of dextran solutions from date extracts were investigated and rheological parameters were evaluated at concentrations of 1.5, 2.5, 5,  together with 10% total solids at 25˚c  using a brookfield rotational viscometer as well as a cone and plate geometry. the experimental results followed the power law model for the best fit and the values of flow behavior index (n) were less than unity (0.49 .93) at all concentrations, revealing the shear thinning nature of the produced dextran. furthermore, dependence of apparent viscosity on concentration was confirmed using the power law model.