Nano-Emulsion Production by Sonication and Microfluidization—A Comparison

TLDR

Emulsion size is a critical factor for volatile entrapment and microencapsulation efficiency. The study evaluated sonication and microfluidization for producing d‑limonene oil‑in‑water nano‑emulsions for subsequent nanoparticle encapsulation. Nano‑emulsions were prepared using a bench‑top sonicator and an air‑driven microfluidizer. Both sonication and microfluidization produced 150–700 nm nano‑emulsions, with the microfluidizer yielding narrower size distributions; increasing sonication time or microfluidization pressure reduced size, but optimal conditions were required to avoid size increase or plateau.

Abstract

The efficiency of sonication and microfluidization to produce nano-emulsions were evaluated in this study. The purpose was to produce an oil-in-water nano-emulsion of d-limonene to apply it in the next step for nano-particle encapsulation. In the entrapment and retention of volatiles or for the microencapsulation efficiency, emulsion size is one of the critical factors. In this study, a bench-top sonicator and an air-driven microfluidizer were used to prepare the emulsions. Results show that, while both methods were capable of producing nano-emulsions of the size range of 150–700 nm, the microfluidizer produced emulsions with narrower size distributions and sonication was more convenient in terms of operation and cleaning. In general, the size of the emulsions decreased with increasing sonication time, or the microfluidization pressure and duration. However, for both sonication and microfluidization, optimal conditions were necessary for emulsification beyond which the emulsion sizes would either increase or have little change with further processing.