Interfacial Engineering of Pickering Emulsion Co-Stabilized by Zein Nanoparticles and Tween 20: Effects of the Particle Size on the Interfacial Concentration of Gallic Acid and the Oxidative Stability.

Zijun Zhao,Wenbo Wang,Yong Cao,Jie Xiao,Yunjiao Chen

doi:10.3390/nano10061068

Zijun Zhao, Wenbo Wang + Show 3 more

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https://doi.org/10.3390/nano10061068

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Abstract

Lipid oxidation is still one of the major food-safety issues associated with the emulsion-based food systems. Engineering the interfacial region is an effective way to improve the oxidative stability of emulsion. Herein, a novel Pickering emulsion with strong oxidative stability was prepared by using zein nanoparticles and Tween 20 as stabilizers (ZPE). The modulation effects of the particle size on the distribution of gallic acid (GA) and the oxidative stability of ZPE were investigated. In the absence of GA, Pickering emulsions stabilized with different sizes of zein nanoparticles showed similar oxidative stability, and the physical barrier effect took the dominant role in retarding lipid oxidation. Moreover, in the presence of GA, ZPE stabilized by zein nanoparticles with the averaged particle size of 130 nm performed stronger oxidation than those stabilized by zein nanoparticles of 70 and 220 nm. Our study revealed that the interfacial concentration of GA (GAI) was tuned by zein nanoparticles due to the interaction between them, but the difference in the binding affinity between GA and zein nanoparticles was not the dominant factor regulating the (GAI). It was the interfacial content of zein nanoparticles (Γ), which was affected by the particle size, modulated the (GAI) and further dominated the oxidative stability of ZPEs. The present study suggested that the potential of thickening the interfacial layer to prevent lipid oxidation was limited, increasing the interfacial concentration of antioxidant by interfacial engineering offered a more efficient alternative.

Highlights

Lipid oxidation is a common deterioration reaction occurring in emulsion-based food systems [1]
We noticed that larger zein nanoparticles led to smaller D3,2 of zein nanoparticles and Tween 20 (ZPE) (Table 1), and the increase in the efficiency of the surfactant to stabilize the interface as more space was available between the largest nanoparticles might serve as a possible explanation
Tween 20 (0.5% v/v) facilitated the interfacial absorption of zein nanoparticles, which enhanced the physical stability of ZPEs

Summary

Introduction

Lipid oxidation is a common deterioration reaction occurring in emulsion-based food systems [1]. Researchers have focused on manipulating interfacial properties to improve the oxidative stability of emulsions [5,6]. Thick interfacial layer inhibited the diffusion of hydrophilic pro-oxidants (such as transition metals) to unsaturated lipids within emulsion droplets, thereby retarding the lipid oxidation. In surfactants-based emulsions, small-molecular-weight emulsifiers decrease the interfacial tension and tend to adsorb and diffuse at the oil–water interface instantaneously, and the adsorption/desorption process is dynamic within a very short time. Experiments have shown that the rate of lipid oxidation in surfactant stabilized oil-in-water emulsions can be decreased by increasing either the head-group or tail-group dimensions of the adsorbed surfactants, which was attributed to their ability to form a thicker interfacial layer that inhibited interactions between pro-oxidants and lipids [4]. Developing emulsions with stronger lipid oxidation stability via forming thicker interfacial layer was proposed

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