Morphology and Characteristics of Starch Nanoparticles Self-Assembled via a Rapid Ultrasonication Method for Peppermint Oil Encapsulation

Starch nanoparticles (SNPs) and peppermint oil (PO)-loaded SNPs were fabricated via an ultrasonic bottom-up approach using short linear glucan debranched from waxy maize starch. The effects of the glucan concentration, ultrasonic irradiation time, and chain length on the SNPs' characteristics were investigated. Under the optimal conditions, i.e., short linear glucan concentration of 5% and ultrasonication time of 8-10 min, SNPs were successfully prepared. The as-prepared SNPs showed good uniformity and an almost perfect spherical shape, with diameters of 150-200 nm. The PO-loaded SNPs also exhibited regular shapes, with sizes of approximately 200 nm. The loading capacity, encapsulation efficiency, and yield of PO-loaded SNPs were ∼25.5%, ∼87.7%, and ∼93.2%, respectively. After encapsulation, PO possessed enhanced stability against thermal treatment (80 °C). The pseudo-first-order kinetics model accurately described the slow-release properties of PO from SNPs. This new approach of fabricating SNPs is rapid, high yield, and nontoxic, showing great potential in the encapsulation and sustained release of labile essential oils or other lipids.