The effects of acetylated distarch phosphate from tapioca starch on rheological properties and microstructure of acid-induced casein gel

Abstract

This study aimed to investigate the effects of acetylated distarch phosphate (ADSP) from tapioca starch on the rheological properties and microstructure of acid-induced casein gel using dynamic rheological tests, creep recovery, confocal laser scanning microscopy (CLSM), and scanning electron microscopy (SEM). The rheological results showed that the casein and casein/ADSP gels displayed shear-thinning behavior. The apparent viscosity and viscoelasticity (G' and G″) of casein/ADSP gels increased with ADSP content, except for 2.0% ADSP. The power law model indicated that ADSP increased the structural strength of the casein/ADSP gels. The creep recovery data were fitted using Burger's model, which showed that the highest instantaneous elasticity and stiffness was observed when the ADSP concentration was 1.5%. The fractal dimension obtained from CLSM indicated that the disorder of the casein network decreased with ADSP concentration. SEM micrographs suggested that the porosity of casein/ADSP gels was decreased by ADSP and that a higher concentration of ADSP (2.0%) broke the continuity of the network structure. The results of this study could potentially facilitate the improvement of the stability of yogurt and provide valuable information for the manufacturers.

Keywords: Acetylated distarch phosphate; Acid-induced casein gel; Microstructure; Rheological properties.