Nanoemulsification of soybean oil using ultrasonic microreactor: Process optimization, scale-up and numbering-up in series

Ultrasonically-induced nanoemulsions have been widely investigated for the development of functional food, cosmetics, and pharmaceuticals due to ideal droplet sizes (DS), low polydispersity index (PDI), and superior physical stability. However, a series of frequently-used ultrasonic set-ups mainly suffered from a low ultrasonic energy efficiency caused by the large acoustic impedance and energy consumption, subordinately confronted with a low throughput, complicated fabrication with complex structure and weak ultrasonic cavitation. Herein, we employed a typical ultrasonic microreactor (USMR) that ensured the high-efficient energy input and generated intense cavitation behavior for efficient breakage of droplets and continuous production of unified oil-in-water (O/W) nanoemulsions in a single cycle and without any pre-emulsification treatment. The emulsifica-tion was optimized by tuning the formula indexes, technological parameters, and numerical analysis using Response Surface Methodology (RSM), followed by a comparison with the emulsification by a traditional ul-trasonic probe. The USMR exhibited superior emulsification efficiency and easy scale-up with remarkable uni-formity by series mode. In addition, concurrent and uniform nanoemulsions with high throughput could also be achieved by a larger USMR with high ultrasonic power. Based on RSM analysis, uniform DS and PDI of 96.4 nm and 0.195 were observed under the optimal conditions, respectively, well consistent with the predicted values. Impressively, the optimal nanoemulsions have a uniform spherical morphology and exhibited superior stability, which held well in 45 days at 4 degrees C and 25 degrees C. The results in the present work may provide a typical paradigm for the preparation of functional nanomaterials based on the novel and efficient emulsification tools.

Automated summary

In this study, a high-efficient ultrasonic microreactor (USMR) was used to continuously produce unified oil-in-water nanoemulsions in a single cycle. The emulsification was optimized to obtain nanoemulsions with uniform morphology and superior stability. This work provides a typical paradigm for preparing functional nanomaterials based on novel and efficient emulsification tools.