Microencapsulation of Tocotrienol by spray drying: Effect of emulsification method

In this study, the effects of high and low energy emulsification methods on the physical properties of spray-dried tocotrienol powder were investigated. The infeed emulsion, incorporating tocotrienol-rich fraction (TRF) as core material, modified starch as the wall material and silicone dioxide as an anticaking agent, was spray-dried using a lab-scale spray dryer. The infeed emulsion produced by high pressure homogenization (HPH) process was finer (D_4,3 < 850 nm) compared to emulsion produced using the conventional rotor-stator homogenization method (D_4,3 > 4μm).  The HPH process further increased the emulsion viscosity by 13.8 to 60% compared to the emulsion produced using rotor-stator homogenization. The increase in viscosity significantly impacted the physical properties of the tocotrienol powders due to the large droplet distribution during the atomization step. Generally, there was a significant reduction in microencapsulation efficiency (MEE) of tocotrienol powder when the oil percentage was increased to 50%. There were no significant (p > 0.05) differences in the MEE of the tocotrienol powder produced using different emulsification methods, except for the powder with 40% oil loading, which showed a significant (p < 0.05) reduction in MEE when the infeed emulsion was homogenized at 800 bar. By using HPH, the tocotrienol powder’s moisture content and hygroscopicity were increased by 19.7 – 45.3% and 9.3-55.8% respectively, compared to the powder produced through the low-energy method. All powder samples exhibited moderately good flowability (Carr’s Index: 2.55 to 3.76) and cohesiveness (Hausner Ratio: 1.01 to 1.09), regardless of the type of emulsification technique used. The findings would help to identify the most suitable emulsification method for producing high tocotrienol-loaded microcapsules with optimal stability and quality.