Affecting parameters on electrospinning process and characterization of electrospun gelatin nanofibers

Electrospinning has been one of the simple, versatile and promising processes to produce continuous nanofibers. Gelatin has been used widely at bulk state in foods for thickening and stabilizing purposes mostly. At nanoscale, electrospun gelatin nanofibers may be used in foods for the same purposes at smaller amounts giving more efficient results. In order to tailor properties of electrospun nanofibers in foods, the influence of affecting parameters on the functions of nanofibers should be known. Our aim was to investigate the influences of the affecting parameters during electrospinning on properties of electrospun gelatin. Gelatin concentrations at 7 and 20% (w/v) were electrospun under 28 or 35 kV of applied voltage. The feed rate was 1 or 0.1 mL/h. Before electrospinning, the electrical conductivity, surface tension and rheological properties of the feed solutions were determined. The morphological analysis showed that only gelatin solution at 20% produced nano-sized fibers. The electrical conductivity, the surface tension, the consistency index and flow behavior index of the gelatin solution at 20% were 4.77 mS/cm, 34.91 mN/m, 1.37 Pa sn and 0.93, respectively. The range of nanofiber diameters increased with the applied voltage. The zeta potential and the diffusion coefficients of dispersions containing gelatin or electrospun gelatin were determined. Both values were higher for dispersions containing electrospun gelatin than for dispersions with gelatin at the same concentration. The zeta potential and diffusion coefficient values of dispersions containing electrospun gelatin decreased as the applied voltage during electrospinning increased. Lower applied voltage resulted in higher zeta potential and diffusion coefficient values for dispersions containing electrospun gelatin nanofibers, which may indicate that these nanofibers can be used for stabilizing food emulsions, whereas smooth nanofiber morphology without bead formation obtained at the highest voltage.