Rheological behavior of emulsion gels stabilized by zein/tannic acid complex particles

In this paper, we report the structure formation and rheological properties of Pickering emulsions stabilized with zein/tannic acid complex particles (ZTPs) over a wide range of particle concentration (1-5%, w/v) and oil content (5-60%, v/v). Microscopy shows that the ZTPs provide stabilization at the droplet interfaces, and that excess ZTPs provide a particle network in the continuous phase to give a solid-like structure to the ZTPs-stabilized emulsions (ZTPEs). The low frequency dependency of G' and low values for tan delta imply that ZTPEs have very elastic networks. The storage modulus (G') of ZTPEs increases in a power-law manner with increasing particle concentration (c(p)) and oil content (phi), which can be scaled as G' similar to c(p)(n) and G' similar to phi(m), respectively. The exponent n decreases with an increase of oil content, and m decreases with increase of particle concentration. This indicates that the structure of the network depends on both the particle concentration and the oil content. The difference in the network structure is also seen in the critical strain gamma(co), since three regimes are observed: for phi <= 20%, gamma(co) decreases with an increase in particle concentration; for 30% <= phi <= 50%, gamma(co) increases with increasing particle concentration; and for phi = 60%, gamma(co) is almost independent on the particle concentration. The results show that the microstructure and rheological properties of ZTPEs can be tuned by changing both the particle concentration and oil content, which may provide interesting features for various applications in industry. (C) 2017 Elsevier Ltd. All rights reserved.