Abstract: Purpose: To investigate the effects of tea polyphenols (TP) on the physicochemical properties of wheat starch and bread quality and their action mechanism. Methods: The impact of TP on the transmittance, gelatinization, retrogradation and gel microstructure of starch was determined together with their influence on the specific volume, texture and color of bread. Furthermore, the interaction mechanism between starch and the major components of TP was observed by molecular dynamics simulation. Results: TP reduced the transmittance of starch paste, promoted the gelatinization of starch, inhibited the retrogradation of starch, and changed the three-dimensional network structure of starch gels. Meanwhile, addition of different amounts of TP had a significant effect on the specific volume, texture and color of bread. TP could change the spatial configuration of starch by affecting the formation of intramolecular and intermolecular hydrogen bonds. Among the phenolic compounds, epigallocatechin gallate bound more stably to starch molecules with a higher proportion of hydrogen bonds and a lower binding free energy. Conclusion: TP show the potential to improve the physicochemical characteristics of wheat starch and bread quality.

Key words: tea polyphenols; starch; physicochemical properties; bread quality; mechanism