Effect of covalent conjugation with chlorogenic acid and luteolin on allergenicity and functional properties of wheat gliadin

In order to develop hypoallergenic wheat products, this study investigated the reduction in allergenicity and improvement in functional properties of wheat gliadin (Gli) through covalent conjugation with chlorogenic acid (CA) and luteolin (LU), as well as the mechanism of covalent conjugation. The upward shifted of the electrophoresis band and the decrease of retention time of chromatographic peak suggested the molecular weight of Gli became larger, and the covalent conjugation was confirmed. Gli was covalently conjugated with CA/LU via the free amino, thiol and tyrosine groups. The grafting rate results showed the degree of covalent interaction between Gli and CA was greater than that of Gli-LU. The structure of Gli was altered distinctly after covalently conjugated with CA/LU, transforming to a more ordered structure. Western blot and ELISA analysis indicated that Gli-CA/LU conjugates showed the lower IgG binding capacity. Further, the thermal stability, antioxidant activity and in vitro digestibility of conjugates were significantly improved (p < 0.05). This research provided theoretical basis and guidance for the production of hypoallergenic wheat products.