Electrospun potato starch nanofibers for thyme essential oil encapsulation: antioxidant activity and thermal resistance

BACKGROUND Thyme essential oil (TEO) is an excellent natural substitute for synthetic compounds to maintain the quality and safety of food products. It acts as an antioxidant agent. We aimed to nanoencapsulate TEO at concentrations of 1%, 3%, and 5% (v/w, dry basis) in electrospun nanofibers made of starch (50% w/v) and formic acid (75% v/v). The rheological parameters of the fiber-forming solutions were measured, and various physical and chemical properties of the nanofibers were analyzed. RESULTS The starch/TEO nanofibers presented homogeneous morphology. The starch nanofibers showed high encapsulation efficiency (EE, 99.1% to 99.8%), which, along with the Fourier transform infra-red (FTIR) spectrum and thermogravimetric analysis (TGA) analysis, indicate strong protection of the phenolic compounds of TEO. Nanofibers with 5% TEO retained up to 50% of the phenolic compounds after exposure to thermal treatment. The antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals of the starch/TEO nanofibers varied from 11.1% to 14.2% and the inhibition values (29.8%, P <= 0.05) against hydroxyl radicals were the same for free TEO and the nanofibers. CONCLUSION Owing to these properties, electrospun starch/TEO nanofibers can be applied in food products or food packaging.