Effect of Proteins on the Physicochemical and Functional Properties of Euryale ferox Starch

To investigate the impacts of proteins from different sources on the gelatinization process and gel structure of Euryale ferox starch, common dietary proteins such as whey protein, rice protein, and gluten were selected in this study. Scanning electron microscopy (SEM), X-ray diffraction (XRD), rapid viscosity analyzer (RVA), and rheological analysis were employed to explore the effect of protein addition on the microscopic structure and functional properties of E. ferox starch. Moreover, Fourier transform infrared spectroscopy (FTIR) and chemical bond analysis were utilized to explore the intermolecular interaction between proteins and E. ferox starch. The results indicated that the addition of 5%–15% proteins led to significant alterations in the physicochemical and functional properties of E. ferox starch. Protein addition significantly decreased the structural uniformity and flexibility of E. ferox starch gels. Whey protein evidently reduced the viscosity and retrogradation value of E. ferox starch paste. Rice protein and gluten postponed the gelatinization process of E. ferox starch, causing a notable increase in its pasting temperature (P < 0.05). The addition of proteins significantly diminished the shortrange order of starch molecules. Notably, the addition of proteins remarkably enhanced the storage modulus (G') and loss modulus (G”) of the gel system, leading to a distinct increase in the surface hydrophobicity and hydrophobic interactions of the system. The enhanced surface hydrophobicity and hydrophobic interactions were beneficial for the stability of the starch gel system. This study demonstrates that the gelatinization process and gel structure stability of E. ferox starch can be regulated and improved by adding proteins from different sources.