Formation of Bioactive-Carrier Hollow Solid Lipid Micro- and Nanoparticles

have attracted a lot of interest to develop health and wellness promoting foods and beverages. However, bioactive lipids are water-insoluble and degrade easily during processing and storage, making their addition into foods and beverages challenging. The main objective of this thesis was to develop a novel green process to form bioactive lipid-carrier hollow solid lipid micro-and nanoparticles using supercritical carbon dioxide (SC-CO2). Specific objectives were to develop hollow solid lipid micro-and nanoparticles using SC-CO2 technology, and to load the hollow solid lipid micro-and nanoparticles with essential oil to develop food grade free-flowing powder antibacterial. Hollow solid lipid micro-and nanoparticles were formed from fully hydrogenated soybean oil (FHSO) using a novel process based on atomization of CO2-expaneded lipid. Hollow spheres (d50%= 278 nm) were obtained using 50 µm nozzle diameter and 200 bar expansion pressure. Shell thickness of the particles decreased with increasing pressure and nozzle diameter. Polymorphism of the particles changed from β to α by decreasing the nozzle diameter. Melting point of FHSO decreased from 69 °C to 57 °C above 120 bar in CO2, and onset melting temperature of the particles was 50 °C due to nanosize. Peppermint essential oil was successfully loaded into the hollow particles using the same process to develop food grade antibacterials. The highest loading efficiency of 47.5% was achieved at 50% initial essential oil concentration at 50 µm nozzle diameter and 200 bar expansion pressure. The release of the loaded essential oil depended on initial essential oil concentration, which was affected by the physical strength of the solid lipid shell. Essential oil-loaded particles obtained at 50% initial essential oil concentration caused 3 log decrease in growth of Pseudomonas fluorescens compared to 2 log decrease with free essential oil. Hollow solid lipid micro-and nanoparticles are promising bioactive-carriers with high loading capacity. Solid lipid shell protects the loaded bioactive from environmental conditions, and provides slow release. The free-flowing powder makes handling and storage convenient, and the simple and clean process makes the scaling up more feasible.