Interfacial Dynamics and Environmental Responsiveness of Double Emulsions Stabilized by Zein Particles and Surfactant Using Microfluidic Techniques

Elucidating the stability dynamics of double emulsions is essential for advancing their sustainable applications in the food industry. This study utilizes microfluidic techniques to investigate the interactions between interfacial components, Tween 80 (Tw80) and zein particles (ZPs), in double emulsions. Our results indicate that the type and concentration of stabilizing agents are critical to emulsion stability with environmental factors further influencing this balance. Specifically, emulsions stabilized by Tw80 primarily exhibited instability through the expulsion of internal droplets (Pe). In contrast, emulsions with ZP concentrations below 0.5% experienced instability due to the coalescence of oil droplets (Po), while those with ZPs concentrations above 0.5% showed instability through Pe, attributed to decreased interfacial relaxation and elasticity. Environmental factors, such as pH, NaCl, and alginate, significantly modulated this stability. Interfacial rheological analyses demonstrated a strong correlation between the emulsion stability and the viscoelastic properties of interfacial films. Lissajous plots revealed that alginate enhanced the elasticity of interface films formed by Tw80 and ZPs, thereby improving the emulsion stability. Additionally, environmental modifications, such as NaCl introduction or pH adjustments, weakened the Tw80 interface strength but accelerated ZP adsorption, ultimately increasing deformation resistance and reducing Pe. This study underscores the potential of microfluidic technologies in advancing colloid and interface science, providing a foundation for the innovative design and precise manipulation of double emulsions.