Effect of Ultrasound on the Electrospinning Encapsulation of Pumpkin Seed Oil in Gelatin-Based Nanofibers

The effects of ultrasonic amplitude (A; 50–80%), sonication time (T; 5–10 min), and pumpkin seed oil (PSO) concentration (C; 10–30%) on the physicochemical and rheological properties of gelatin–acetic acid polymer solutions and their corresponding PSO emulsions prior to electrospinning as well as on properties including morphology, thermal properties (DSC and TGA), FTIR spectra, fiber diameter (FD), and the encapsulation efficiency (EE%) of fatty acids (FAs) and carotenoids (TC) of the resulting electrospun fibers were evaluated. Stirred agitation (24 h) was used as a control. The viscosity of the polymeric solutions was significantly reduced by A for short time periods (p < 0.05). The addition of PSO increased the emulsion viscosity, affecting morphology, FD, and the EE%. The EE% of TC, oleic (OA), palmitic (PA), and stearic (SA) acids showed no significant difference compared to the control. However, for linoleic acid (LA), the EE% was lower with ultrasound treatment. Treatments with A = 50% for 10 min with 10% PSO resulted in homogeneous fibers (0.29 µm) without agglomerates with thermal stability and an EE% of 42% and 26–34% for TC and FAs, respectively. These results show that ultrasound is an effective alternative for homogenization that promotes the formation of nanofibers with PSO via electrospinning.