Microstructure, pasting and textural properties of wheat starch-corn starch citrate composites

Corn starch citrate (CSC) is a type IV resistant starch (RS) and its inclusion in bakery products has several health benefits. Therefore, in this study, 0, 10, 20, 30 and 40% of wheat starch (as the main constituent of wheat flour) was replaced by CSC and its influences on solubility, water absorption, scanning electron micrographs (SEM), pasting properties, texture profile analysis (TPA) and stress-relaxation behavior of wheat starch gels were determined. By the increase in CSC level, solubility and water absorption were decreased. The CSC addition led to an increase in the pasting temperature but decreased other pasting parameters. The control wheat starch gel had the highest firmness, cohesiveness, springiness, gumminess and chewiness. However, inclusion of CSC decreased these parameters. Stress-relaxation data showed that the Ee, E1 and τ1 parameters were decreased by the increase of CSC level and the electron micrographs revealed that the control starch gel had a denser structure and addition of CSC formed gels with larger cells and thinner cell walls. To summarize, increasing the SCS substitution level provided a remarkable decrease in resistance of wheat starch gel as revealed by the experiments.