The Thermal Properties of Gliadins and Glutenins Fortified with Flavonoids and Their Glycosides Studied via Thermogravimetry (TGA) and Differential Scanning Calorimetry (DSC)

Thermal analyses (TGA and DSC) were used to determine the thermal properties of gliadins and glutenins extracted from a model wheat dough fortified with flavonoids and their glycosides. As flavonoids, quercetin; naringenin; hesperetin; and their glycosides, rutin, naringin, and hesperidin, were used in amounts of 0.05%, 0.1% and 0.2%. An analysis of TGA parameters showed that samples fortified with flavonoids/glycosides led to an increase in the weight loss of gliadin. The thermal behavior of gliadins enriched in polyphenols depended on the structure and size of the added compound. The weight loss of glutenin did not change in the presence of the studied polyphenols. An analysis of the difference TGA thermograms showed that quercetin, rutin, and naringin interacted with gliadins through the OH group located at the B ring in the 4’ position. Additionally, quercetin formed chemical bonds with the polypeptide chains of glutenins. The DSC thermograms were consistent with the TGA results, which suggest interactions between gliadin and quercetin.