Effect of Emulsion Size on the Physic Properties and Oxidation Stability of Orange Oil Microcapsule

To explore the emulsion size effects on the physic properties and oxidation stability of spray-dried orange oil microcapsule, different particle size emulsion were prepared by high pressure homogenization (1000, 2500, 3500 and 22000 psi) with modified starch and maltodextrin as wall materials and then spray-dried to produce orange oil microcapsule. The physical properties of microcapsules were evaluated including the average particle size, oil encapsulation efficiency, water content, microstructure and reconstituted emulsion size. Limonene oxidation speed was analyzed to evaluate the storage stability of microcapsule and predicted shelf-life. The results showed that emulsion particle size decreased with the increasing of homogenization pressure. The emulsion size had no significant effect on the total oil content (1.5 g/20 g), oil encapsulation efficiency (>95%) and water content (<4%) of the microcapsule, but it would affect the average particle size, micromorphology of the microcapsules and particle size distribution of reconstituted emulsion. The microcapsule had a smaller average particle size and smoother surface when the emulsion particle size decreased. The reconstituted emulsion had a narrower particle size distribution. Microcapsules were stored at 37℃ for 5 weeks to detect change of limonene 1, 2-epoxide/limonene (mg/g). According to zero-order model, the shelf life of the microcapsules prepared at 22000 psi was predicted as 11 weeks, which was 2.97~4.63 times that of the other microcapsules. The results can provide a theoretical reference for the optimization and quality control of spray drying essential oil microcapsules.