Electrospinning of whey and soy protein mixed with maltodextrin - Influence of protein type and ratio on the production and morphology of fibers

The production of food-grade fibers from maltodextrin with either whey protein isolate or soy protein isolate was evaluated in a needleless electrospinning setup. The ratio of maltodextrin to protein was varied. Higher protein content generally led to a higher electrical conductivity and viscosity. Compared to WPI samples, the use of SPI decreased the surface tension of the spinning dispersions while at the same time increasing the electrical conductivity from 0.39 +/- 0.00 mS/cm (WPI 80:5) to 0.64 +/- 0.01 mS/cm (SPI 80:5) and the apparent viscosity ((gamma) over dot = 100 s(-1)) from 4.58 +/- 0.14 Pa.s (WPI 80:5) to 5.14 +/- 0.09 Pa.s (SPI 80:5). The high viscosity was identified to hinder electrospinning and the maltodextrin-SPI fibers had lower production rates of 0.50 +/- 0.25 g/h (SPI 80:5) and higher diameters 4.74 +/- 2.33 mu m (SPI 80:5) compared to maltodextrin-WPI fibers (0.98 +/- 0.13 g/h and 2.85 +/- 0.95 mu m for WPI 80:5). Removing the insoluble fraction of the SPI and only using the soluble soy protein (SSPI) with maltodextrin for electrospinning resulted in a lower viscosity (4.63 +/- 0.05 Pa.s for SSPI 80:5) and better spinning results (0.5 g/h +/- 0.06). FTIR analysis and protein measurement showed that the resulting fibers consisted of both the maltodextrin and the proteins. The protein content in the fibers was thereby linked to the spinnability and fiber appearance.