Optimization of pullulan production from pomegranate waste by A.pullulans

In this study, optimization of fermentation conditions for pullulan production by Aureobasidium pullulans (KY767023) from pomegranate waste was investigated. Response surface methodology was used to evaluate the effects of three factors (initial pH, inoculum size and ratio of liquid to solid) on pullulan yield in solid-state fermentation (SSF). Results of these experiments indicated that maximum pullulan concentration (50.5 ± 0.35 g/kg) was obtained at the optimum levels of process variables (initial pH 7.75, inoculum size 5% v/v, ratio of liquid to solid 1:2.5). Furthermore, physicochemical characteristics of the obtained pullulan at the optimum conditions were studied. The emulsifying activity of extracted pullulan was 63% .The emulsion stability was 60.5% at 4 °C and 58.5% at 25 °C after 30 days of storage. The results of viscosity curves at different concentration demonstrated that the solutions of pullulan at low concentrations (0.1-0.5 % w/v) showed nearly Newtonian flow behavior, and as the concentration of pullulan solution increased, the behavior changes from Newtonian to pseudoplastic flow. FT-IR of the pullulan produced from pomegranate by-products revealed the presence of α (1→6) linked maltotriose units.