Effect of calcium/sodium addition on rice starch-chickpea protein hydrolysate complexes: Microstructure, rheological properties and digestibility

In the present study, we investigated for the first time the effects of different concentration ranges (0-2 %, w/w) of CaCl2 and NaCl on the microstructure, physicochemical properties and digestibility of rice starch-chickpea protein hydrolysate (RS-CPH) complexes. The results showed that CaCl2 (0-1.5 %, w/w) and NaCl (0-1 %, w/ w) enhanced the hydrogen bonding interactions between RS and CPH. The CLSM images visualized that the addition of salt resulted in a more uniform distribution of CPH in the RS matrix. However, the XRD results showed a decrease in the diffraction intensity of the complexes, implying an increase in the amorphous region of the complexes. In addition, 1.5 % (w/w) CaCl2 and 1 % (w/w) NaCl reduced the rapidly digestible starch content of the complexes to 36.63 % and 37.20 %, respectively. These results highlight the innovative application of salt modulation in the RS-CPH system and offer a theoretical foundation for developing functional foods with controlled starch digestibility.