Effect of wet-media milling on the physicochemical properties of tapioca starch and their relationship with the texture of myofibrillar protein gel

Abstract

This study investigated the effect of wet-media milling on the physicochemical properties of tapioca starch (TS) and the relationship of these properties with the texture and microstructure of fish myofibrillar protein (MP) gel. The proposed wet-media milling was shown to linearly increase the transmittance of wet-media milled TS (WM-TS) suspensions and gradually induce the Tyndall effect, leading to an efficient reduction of the particle size from micro-scale (14.49 μm) to nano-scale (140 nm), an increase in specific surface area and dispersion stability, and a decrease in zeta-potential, gelatinization temperature and viscosity. Among these properties, particle size, specific surface area and zeta-potential showed an extremely significant correlation with the texture of MP/WM-TS composite gel. Furthermore, milling increased the O/C ratio to expose more C–O bonds on the surface of WM-TS, which was well correlated with the enhanced texture of the MP/WM-TS composite gel. Additionally, milling disrupted the granular, crystalline and lamellar structures of TS, and transformed the TS granules from spherical state to heterogeneous state and then to homogeneous state, with a surface-to-mass fractal transition, contributing to the continuity of microstructures and compatibility of MP/WM-TS gels. Overall, the texture of MP/WM-TS gel was significantly affected by particle size and surface features (including specific surface area, zeta-potential and the exposure of O element) rather than the dispersion stability and viscosity of starch slurry.