Stability study of ethylcellulose coated-tocotrienol microcapsules prepared by solvent evaporation and spray drying techniques

Objective: Tocotrienol is a natural Vitamin E compound with greater antioxidant activity than tocopherol. However, tocotrienol is considered unstable, which limits its handling and use in various product formulations. In this study, to enhance the stability of tocotrienol, tocotrienol oil was converted into a powder through a microencapsulation method using ethylcellulose (EC) as the coating material. Methods: Tocotrienol microcapsules were formulated with EC in ratios of 1:2 and 1:3 by solvent evaporation (SE) and spray drying techniques. The obtained microcapsules were then characterized in terms of shape and morphology, particle size, entrapment efficiency, percentage yield, flow properties, water content, swelling, and drug release. In addition, stability studies at both room temperature and elevated temperatures were performed. Results: Our results demonstrated that the tocotrienol microcapsules were of a white-yellowish powder of irregular shape, with particle sizes between 1 nm and 60 nm and entrapment efficiency of 21.60% and 99.75%. After 12 weeks of storage at room temperature, the remaining level of tocotrienol in the microcapsules was 96.46-97.74%. In the accelerated stability study at elevated temperatures, the resulting values ranged from 1.02x10-5 to 1.32x10-5/h. Thus, the predicted shelf-life (t90) of the microencapsulated tocotrienol was determined to be between 11.01 and 14.27 months. Conclusion: The microencapsulation of tocotrienol with EC using SE and spray drying techniques produced a solid form of tocotrienol that was considerably more stable than the natural form of tocotrienol.