Influence of the surface/volume ratio on the rheological properties of starch dispersions

Abstract

This study aims to evaluate the influence of the surface/volume granule ratio of amaranth, corn, and potato starches on the rheological properties of pastes and gels obtained at 5 and 10% solids concentration through granulometry, scanning electron microscopy, rotational, and dynamic rheological measurements. The granule size distribution and the surface/volume ratio drove the rheological behaviour as a function of temperature and concentration. At a concentration of 10%, the consistency index of corn starch (CS) paste was 147.25 Pa•s n (n -flow behavior index), a higher value compared to pastes from potato starch (PS), 86.54 Pa•s n , and amaranth starch (AS), 44.48 Pa•s n . The lowest values of the loss angle tangent (Tan δ) in CS (0.052 and 0.035) at both solids concentrations suggested a better gel conformation. Noticeable changes in consistency index and storage modulus were observed in CS. A theoretical analysis of the surface/volume ratio change showed that CS reached a 2.2 value, much lower than the 4.5 and 5.8 values for PS and AS, respectively. These findings provide additional criteria for the food industry when choosing starches with suitable rheological behaviour as a function of surface/volume granule ratio and solids concentration.