Optimal conditions for the encapsulation of menthol into zein nanoparticles

Abstract Zein is one of the seed storage proteins found in the endosperm of maize. It is soluble in aqueous ethanol solutions with high ethanol content, and forms aggregates when the ethanol content of the solution is lowered. This unique structural variation has long been utilized to prepare nanoparticles that carry hydrophobic drugs. In this research, the optimal conditions for the encapsulation of menthol, the major component of peppermint oil, into zein nanocapsules were investigated. The major controlling factors that govern the encapsulation efficiency of the procedure include ethanol content of the solvent used for the dissolution of zein, concentration of menthol in the solvent, the mass ratio of menthol/zein, and ethanol content of the product solution. This research reveals how the highest encapsulation efficiency can be achieved by producing nanocapsules at optimal conditions. This research also indicates that the procedure for finding optimal conditions for the encapsulation of menthol can also be applied to the case of many other chemical compounds by making use of the phase diagram for solute/ethanol/water.