The loosening effect of tea polyphenol on the structure of octenyl succinic anhydride modified waxy maize starch

Octenyl succinic anhydride modified waxy maize starch after heat-moisture treatment (HT-OSAS) is a heat-stable slowly digestible starch (SDS), but the mechanism is poorly understood. Tea polyphenols (TP), as a probe with hydrophobic moiety, were employed to study the structural basis for its slow digestion. The content of RS (8.91%) in the HT-OSAS was significantly increased by TP in a dose-dependent manner (19.06% at TP of 15%) while there is a slight decrease of SDS content (34.85-30.63%). However, after retrogradation for one week, TP significantly reduced the SDS content (29.79%-15.67%). Additionally, TP increased the hydrodynamic radius of HT-OSAS (60-102 nm), but reduced its emulsifying activity (-35%), gelatinization enthalpy (-45%), and viscosity (-66%), demonstrating an inhibitory effect of TP on the association of HT-OSAS molecules, and a compact physical structure of HT-OSAS formed through OSA-mediated hydrophobic interaction is likely the basis to its slow digestion property. Novel strategies to densify the physical structure of starch could improve the nutritional quality of starch with a slow digestion property.