Rheology, thermal properties, and microstructure of heat-induced gel of whey protein-acetylated potato starch

The objective of the present work was to investigate the effects of acetylated potato starch (APS) on the rheological and thermal properties and the microstructure of a heat-induced gel of whey protein isolate (WPI) using small-amplitude oscillatory rheometry, differential scanning calorimetry (DSC), dynamic light scattering (DLS), and scanning electron microscopy (SEM). The rheological results indicated that the elastic (G') and viscous modulus (G) of the WPI-APS systems increased as the concentrations of APS increased. During heating and cooling, the rheological profiles of the WPI-APS systems exhibited continuous increases in G' at temperatures more closely related to those observed for WPI rather than APS. DSC results indicated that increasing APS concentration had no influence on the individual phase transition of WPI and APS. An analysis of the Flory-Huggins parameter chi(12) suggested an obvious phase separation between WPI and APS in the WPI-APS system. The comprehensive analytical results indicated that the gelatinization for APS was earlier than the denaturation for WPI, contributing to the formation of larger-sized WPI-APS aggregates. The results could provide a theoretical foundation for food preparation containing WPI and APS.