Effect of Citric Acid Modification on Physio‐Chemical, Structural, Rheological, Thermal Properties, and In Vitro Digestibility of Amaranthus paniculatus (Rajgeera) Starch

Abstract

In this study, starch is treated with different concentrations of citric acid (CA, 5, 10, 20, and 30 g/100 g dry basis) which leads to the production of citrate starch. The effect of CA concentration on physio‐chemical, structural, rheological, thermal properties, and digestibility is analyzed. A Fourier transform infrared (FTIR) spectroscopy Stands for FTIR peak at 1728 cm−1 is observed, indicating ester bond formation between CA and starch molecules. A nonsignificant change in the crystalline pattern is observed between native and citrate starch, whereas a decrease in relative crystallinity from 15.75% to 6.91% is observed. With the increase in the degree of substitution, gelatinization decreases, and gelatinization's enthalpy (ΔH) decreases from 13.72 to 9.63 J g−1. The rapid digestible starch (RDS) decreases by CA treatment, whereas slow digestible starch (SDS) and resistant starch (RS) increase significantly from 32.81 g/100 g dry basis to 39.45 g/100 g dry basis and 9.87 g/100 g dry basis to 25.26 g/100 g dry basis, respectively.