Combined Effects of Quercetin and NaCl Concentrations on Wheat Gliadin Structure and Physicochemical Properties

BACKGROUND Polyphenols may interact with protein via covalent bond and non-covalent interaction, improving the structures and functional properties of protein. The cross-linking between polyphenol and protein is susceptible to salt concentrations. Our study investigated the combined effects of quercetin (Q) and NaCl concentrations on wheat gliadin (G) structure and physicochemical properties. RESULTS Q and NaCl addition resulted in a more compact protein microstructure. The improved foaming and emulsifying properties indicated that the modified G might be potent as a novel surface-active agent. Differential scanning calorimetry analysis indicated that Q protected the thermal stability from destruction at 50 mM and 200 mM NaCl concentrations, with narrower protein denaturation peaks. Fourier transform infrared and the Raman spectral analyses showed the secondary structural and microenvironmental changes of G. NaCl addition imparted a rearrangement of hydrogen bond in the polypeptide chain and the disorder of protein structure, while Q enhanced the transition from β-sheet and random coil to α-helices and β-turns, forming a more ordered structure. Moreover, the interaction between G and Q determined significant disulphide bridges conformational rearrangements in protein. CONCLUSION Results showed the benefits of natural food additives in food processing, which might have potentials in improving the structure and physicochemical properties of protein-based foods. This article is protected by copyright. All rights reserved.