Computer simulation reveals interfacial distribution behaviors of gallic acid in zein particle and tween 20 co-stabilized pickering emulsions: Impact on oxidative stability

The interfacial-bulk phase distribution behavior of antioxidants is closely related to their anti-oxidative efficiency. In this study, the dynamic distribution behavior of gallic acid (GA) in a zein particles-Tween 20 co-stabilized emulsions (CPE) and its impact on the oxidative stability of CPE were elucidated via a combined experimental and Dissipative Particle Dynamics (DPD) method. As the concentration of TW20 increased, the competitive displacement of Zp from the interface was observed. Consequently, the interfacial loading of Zp decreased, leading to a corresponding decrease in the content of GA on the interface. The study's pseudo-phase model provided quantitative data indicating that the interfacial partition percentage of GA decreased from 70.72% to 48.63%, while the interfacial adsorption rate of GA decreased from 0.039 to 0.015. A notable discovery was made in emulsions solely stabilized by Zp, where 17.58% of GA was lost at the interface through free diffusion. However, in CPE, this loss was significantly reduced to 9.12%. This reduction was achieved by maintaining an appropriate concentration of TW20 (ranging from 0.19 to 1.91 mM), which facilitated a higher interfacial distribution of GA in CPE. Additionally, inhibiting the free diffusion of antioxidants at the interface, as indicated by the diffusion coefficients ranging from 20.51 to 4.45, contributed to the improved oxidative stability of the CPE. The study not only provided insights into the phase-interface distribution behavior of antioxidants in emulsions but also offered in-situ determination methods to guide the interfacial engineering of emulsions.