Effect of epigallocatechin gallate on the gelatinisation and retrogradation of wheat starch.

The effects of epigallocatechin gallate (EGCG) on the gelatinisation and retrogradation characteristics of wheat starch (WS) were investigated using rapid viscosity analysis (RVA), X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The addition of EGCG resulted in decreased peak viscosity, trough viscosity, final viscosity and setback value of WS, as shown by RVA tests. After storage at 4 °C, observations by XRD and TGA revealed that the EGCG-WS complex had lower crystallinity and thermal stability than the control, indicating that EGCG retarded the retrogradation of WS. FT-IR and Raman spectroscopy results showed that EGCG formed hydrogen bonds with WS, through which EGCG could interfere with the reassociation of starch chains during storage, thereby delaying retrogradation. EGCG may therefore prove to be a useful additive in wheat products and in nutrition-related applications.