Effects of Sugar, Salt, and Whey Protein on the Viscoelastic Properties of Pregelatinized Rice Flour Dough

The effects of sugar, salt, and whey protein concentrate (WPC) on the rheological properties of pregelatinized rice flour (PRF) doughs were evaluated using a response surface methodology (RSM).Sugar (0%-10%), salt (0%-2%), and WPC (0%-5%) were designated as independent variables, and various rheological parameters of PRF doughs were defined as response variables.Thirteen formulations were generated according to a Box-Behnken design.The rheological behavior of the dough systems was characterized using frequency-sweep measurements (G′ max , G″ max , η* max , and tan δ) and creep-recovery analyses (γ max , γ r , γ e , and γ nr ).Sugar, WPC, and salt decreased G' max , G" max , and η* max significantly through competitive hydration with pregelatinized rice starch, with a concomitant increase in tan δ.In particular, salt further weakened the binding stability of the starch-protein network by increasing the ionic strength within the dough system.Consistent patterns were observed in the creep-recovery responses: formulations containing sugar, salt, and WPC exhibited higher γ max and γ nr , which are indicative of viscous-dominant and structurally weakened networks.In contrast, the highest structural stability was obtained at low sugar levels and intermediate concentrations of salt and WPC.The regression models generated via RSM were robust, exhibiting high coefficients of determination (R 2 =0.81-0.98).The optimal formulation was identified as 2.25% sugar, 0.97% salt, and 2.55% WPC, resulting in a rheological behavior exhibiting adequate structural stability and improved processability.Overall, this study elucidates the interactive effects of the three additives on the rheological behavior of PRF doughs and provides foundational insight for improving the quality and manufacturability of PRF-based products.