This work investigated the suitability of lipid carriers as potential encapsulation method to improve the physical and chemical stability of microalgae oil high in docosahexaenoic acid (DHA). Lipid carriers with various oil contents were successfully prepared by a microfluidization method using stearic acid as solid lipid, microalgae oil as liquid lipid, and poloxamer 188 as surfactant. Results show that the mean particle diameter of the lipid carriers was in the range of 300 to 350 nm with the polydispersity index below 0.2. The lipid carriers were found to have spherical shape when examined under the transmission electron microscope. Data from the encapsulation efficiency and loading capacity indicate high distribution of microalgae oil throughout the lipid carriers and good physical stability as reflected by the particle size and size distribution during storage. Furthermore, the lower DPPH scavenging activity of lipid carriers compared with that of free microalgae oil suggests better chemical stability of microalgae oil encapsulated in lipid carriers. The addition of microalgae oil into lipid phase could disturb the crystalline order and form lattice defects to enable encapsulation of DHA as revealed by the results from differential scanning calorimetery. Current results suggest that this type of novel lipid carriers could be an efficient and promising carrier system for delivery of microalgae oil.
There has been limited report on the application of lipid carriers for encapsulation of microalgae oil with high DHA content for food application. In this study, lipid carriers have been shown to improve the physical and chemical properties of microalgae oil. These lipid carriers could be produced as functional ingredients to be incorporated into functional food products such as frozen desserts, drinks and beverages, and bakery products. High-pressure homogenization, an established method in pharmaceutical industry, could be applied to achieve high-volume production of lipid carriers for food application. The results from this study would, therefore, provide useful insight into the application of DHA-rich microalgae oil in food industry.