Soybean protein isolate‐rice starch interactions during the simulated gluten‐free rice bread making process

Abstract Gluten‐free bread (GFB) is usually of poor quality due to lack of gluten. Addition of exogenous protein is one of the important ways to improve the quality of GFB products. In this study, different levels of soybean protein isolate (SPI) mixed with rice starch (RS) system were prepared to simulate different processing stages during bread making. Differential scanning calorimetry (DSC), X‐ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), rapid viscosity analysis (RVA), confocal laser scanning microscopy (CLSM), texture analyser and rheometer were used to analyse the effects of SPI on the structural, microstructure and functional properties of RS. The results showed that: hydrogen bonds could be formed between SPI and RS, thus improving the stability of RS; compared with RS, the ∆H and setback values of the blend were reduced by 43.79% and 34.53%, respectively, when SPI was added at 12%; and the storage modulus (G') and loss modulus (G") reached the minimum value at 9% SPI content. CLSM and texture analysis show that the addition of protein inhibits the leaching of starch, reduces the hardness, chewiness and gumminess of the system, which is conducive to the quality of GFB.