"Exploring the interface dynamics of emulsion gel via a novel non-destructive technique provides insights into the underlying mechanism of gel formation, water mobility, functionality and structural variations”

Abstract

Tri-frequency ultrasound (TFU) at 20-40-60 kHz was used to systematically examine the effects on the multi-scale network structure of an emulsion gel containing orange essential oil prepared with glycosylated whey protein (WP). Treatment intervals of pre-and-post 10, 20, and 30 min were utilized to evaluate the influence and interactions on functional (particle size, zeta-potential), rheological (storage modulus (G') and loss modulus (G''), and oxidative stability (conjugated diene and peroxide value). The optimized tri-frequency pre- and post-treated sample demonstrated enhanced physical stability as compared to the un-treated sample, as evidenced by droplet size, (from 468.14 ± 0.56 to 214.21 ± 0.42 nm), ζ-Potential (mV) (from -29.67 ± 0.31 to -39.98 ± 1.42), and structural morphology. Structure analysis using FTIR that the aforementioned improvements were made possible through TFU enhanced hydrogen bonds, molecular arrangements with greater order, and improved intermolecular compatibility. XRD results showed gradual shift from 8.32° to 8.64° and from 19.2° to 19.5°, respectively. TFU post-treatment gels exhibited higher viscosity, more pronounced pseudoplastic behavior compare to pre-treatment, attributed to strong interaction forces and three-dimensional gel network. Our results provide valuable insights into the application of multi-frequency ultrasound as a promising technique for designing protein emulsion gels tailored for nutrient delivery systems.