Abstract: α-tocopherol is a natural antioxidant and nutritional supplement and has been widely used in the food field. However, its scope of application is greatly limited due to its high susceptibility to environmental factors including oxygen, light and metal ions, ease of inactivation and water insolubility. In this study, α-tocopherol was encapsulated in chitosan nanoparticles (α-TOCCSNPs) by emulsification-ionic gelation method. To optimize the process, the average particle size (APS) and encapsulation efficiency (EE) were investigated as a function of chitosan (CS) concentration, α-tocopherol concentration, mass ratio of CS to sodium tripolyphosphate (TPP), pH and stirring speed by one-factor-at-a-time and orthogonal array designs. The CS nanoparticles were characterized by dynamic light scattering (DLS), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscope (SEM) and evaluated for release pro?les and antioxidant properties in vitro in order to provide a theoretical basis for the application of α-tocopherol to inhibit lipid oxidation in cured meat products during storage. The results demonstrated that the optimal conditions for preparing α-tocopherol loaded CS/TPP nanoparticles were as follows: CS concentration, 1 mg/mL; mass ratio of CS to TPP, 7:1; pH, 4.5, and stirring speed, 900 r/min. The APS and EE of α-tocopherol loaded nanoparticles were 214 nm and 51.65%, respectively under the optimized conditions. The FTIR spectrum con?rmed that the encapsulation of α-tocopherol was achieved by electrostatic adsorption, and the SEM observation showed uniform average particle size distribution and regular spherical morphology. The α-tocopherol chitosan nanoparticles had sustained antioxidant activity in vitro.

Key words: α-tocopherol, chitosan nanoparticles, characterization, sustained release, antioxidant activity