Optimization and Characterization of a Nanostructured Lipid Carrier Containing α-Tocopherol/Tocotrienol Prepared Using Rice Bran Oil and Palm Kernel Stearin

Abstract

α-tocopherol and tocotrienol are known for their antioxidant properties and cannot be produced directly in the human body. However, their use remains limited because of their low solubility, instability, and susceptibility to oxidation and high temperatures This study aims to identify the optimal formulation of a carrier of phytonutrient αtocopherol/tocotrienol prepared via ultrasonication with rice bran oil (RBO), palm kernel stearin (PKS), and Tween 80 and determine the characteristics of the optimal formulation during storage. The box-behnken design (three factors and levels) was used to determine the formulation of a nanostructured lipid carrier -tocopherol/tocotrienol (NLC-TT) based on the solid: liquid lipid ratio, total lipid: surfactant ratio, and sonication time. The optimal NLC-TT formulation prepared with a solid: liquid lipid ratio of 7.5:2.5, total lipid: surfactant ratio of 1:3.9, and sonication time of 12 min and 6 s yielded a particle size of 126.7 nm, a polydispersity index of 0.339, a zeta potential of -31.7 and an encapsulation efficiency (EE) of 96.4%. During storage, NLC-TT and NLC-free particles exhibited particle sizes of 123.6-144.2 nm, polydispersity indices of 0.245-0.339, zeta potentials of -31.7--39.6 mV, EEs of 96.4%-89.6%, stabilities of 2.02-1.63, peroxide values of 0.05-0.25 mEqO2/kg, anisidine values of 0.07-1.60 and free fatty acid contents of 0.04%-0.08%. RBO and PKS are potential lipid-based carrier systems for tocopherol/ tocotrienol and exhibit good stability during storage.