----Evaluation of Design and Fabrication of Food-Grade Nanofibers from Chitosan-Gelatin for Nanoencapsulation of Stigmasterol Using the Electrospinning Method.

In this research, electrospinning method was employed to fabricate food-grade nanofibers (NFs) from chitosan-gelatin combination for stigmasterol encapsulation. The spinnability of mixed chitosan and gelatin solutions was investigated at different polymer ratios, and the physicochemical properties of the NFs were evaluated. The mixture solution of chitosan (1.5 % w/v) and gelatin (20 % w/v) in acetic acid indicated spinnability under the following conditions: the ratio of 25:75, voltage of 17 kV, and 15 cm capillary collector distance with a flow rate of 0.2 mL/min. Stigmasterol (0.04 % w/v) was incorporated into NFs of chitosan-gelatin at a respective ratio of 25:75. Encapsulation efficiency (EE) of loaded stigmasterol was found to be 87 ± 5 %. The antioxidant ability of loaded stigmasterol was considerably higher than that observed for free stigmasterol. Scanning electron microscopy (SEM) results demonstrated the formation of the ultrathin fibers with no bead (with diameters of 217 ± 43 nm). The concentration of polymeric solution and viscosity had a notable effect on the electrospinning efficiency of the chitosan-gelatin-based NFs. The thermal stability of chitosan and gelatin fibers was more than that of native gelatin and chitosan. The in vitro stigmasterol release from these NFs followed a controlled-release pattern. The released phytosterol from chitosan formula was less than from those without chitosan formula (46 ± 3 % and 96 ± 4 % respectively). The obtained results suggested that gelatin had a high potential for enhancing the spinnability of chitosan under acidic conditions at optimized concentrations.