Optimization of the emulsification-diffusion method using ultrasound to prepare nanocapsules of different food-core oils

The aim of this study was to determine the optimal processing conditions for preparing nanocapsules by the emulsification-diffusion method using ultrasound in the homogenization step. β-carotene (300 g/L) was used as the active compound core and central composite design (CCD) to establish optimal conditions of ultrasound power (W), encapsulated β-carotene (mg/L), and poly-ε(caprolactone) content (PCL; mg/L). Desirability functions were used to explain the behavior of the independent variables, which included particle size (PS), the polydispersity index (PDI), zeta potential (ζ), and encapsulation efficiency (EE). Overall desirability was used to ascertain the optimum processing conditions for nanocapsules preparation. Results showed that the optimal conditions were 54.73 W of ultrasonic power, 1291 mg/L of β-carotene, and 755 mg/L of PCL, since they produced values for PS, PDI, ζ, and EE of 228 nm, 0.054, −25.42 mV, and 78.23%, respectively. Density studies confirmed the formation of capsular systems. To verify the design, lemon oil, rosemary oil and curcumin were assayed as encapsulating oils with PCL and ethyl cellulose as the membrane polymers. This produced a PS of 107-157 nm, a PDI of 0.138-0.207, a ζ of −7.58 to −3.08 mV, an EE of 27.17-92.29%, and densities of 1.004-1.029 g/mL for the different oils.