Fabrication of gel-like emulsions with γ-zein particles using microfluidization: Structure formation and rheological properties
2022
Yang, Qianwen | Zheng, Qianwang | Jin, Manhong | Chen, Ya | Guo, Liqiong | Lin, Junfang | Zou, Yuan
In this work, γ-zein, which is a type of cysteine rich prolamine in corn, was prepared into particles for fabricating stable gel-like emulsions. The effects of homogenization pressure (0.1–120 MPa) on structure formation and rheological properties of emulsions were systematically studied. Microscopy showed that γ-zein particles provided stabilization at droplet interfaces, and that excess protein particles provided a particle network in continuous phase, and microfluidization significantly decreased droplet size and induced to form droplet clusters and gel-like network. With an increase of homogenization pressure, protein content adsorbed at droplet interfaces and entrapped within gel-like structure of emulsions increased, and more hydrophobic interactions and disulfide bonds between protein particles were formed. As a result, stronger gel strength of emulsions were observed, for example, apparent viscosity, storage modulus (G'), loss modulus (G''), and G'/ G'' crossover strain (γcₒ) increased, the frequency dependency of G' (n, G′ ∼ ωⁿ) decreased. Also, Lissajous curves were used to further understand the non-linear viscoelastic behavior of these emulsions. Emulsions prepared without microfluidization (control, 0.1 MPa) showed a weak gel structure with viscous-dominating behavior at high strain, while emulsions prepared with microfluidization showed predominantly elastic behavior at low strain, and plastic-dominating behavior at high strain. These findings showed that cysteine rich protein based- emulsion gels with tunable microstructure and rheological properties can be easily produced by controlling the homogenization pressure.
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