The influence of selected polyphenols on the gluten structure - A study on gluten dough with application of FT-IR and FT-Raman spectroscopy

Abstract

FT-IR and FT-Raman spectroscopies were applied to study interactions between gluten proteins and eight polyphenols in gluten dough (without starch). Polyphenols were added in the amount of 0.05%, 0.1% and 0.2% to gluten dough. Based on the FT-IR spectra, the studied compounds were divided into three groups, depending on the type of changes they induced in the secondary structure of gluten proteins. The changes induced by each polyphenol group were closely related to the different number and type of functional groups present at the phenolic, as well as their molecular size. Gallic, ellagic and tannic acid caused an increase in the number of the disulphide bridges in the g-g-g conformation. All tested phenolic acids increased the tryptophan band intensity and changed the environment of this amino acid to more hydrophobic. Such a result indicated the formation of a more ordered structure and the folding of polypeptide chains.