This research was aimed to study the effects of three independent variables including konjac concentration (0.1-0.4%), pH level (pH 5-9) and NaCl concentration (0.2-0.6 M) on foaming properties (foaming capacity and foaming stability) and emulsifying activity of milk protein concentrate (MPC), egg white powder (EWP) and milk protein concentrate/egg white powder (1:1) blend (MPC/EWP) using the response surface methodology. In addition, the effect of konjac addition at 0.1 to 0.4% on physicochemical and sensory properties of gluten-free muffins, made with a total wheat substitution by a rice/corn (1:1) mixed flour, was also investigated. A central composite rotatable design (CCRD) revealed the high values of coefficient of determination (R2) (R2>0.8) and non-significant lack-of-fit, indicating the reliability and significance of all predictive models for foaming capacity, foaming stability and emulsifying activity of MPC, EWP and MPC/EWP. The greater effects were found in konjac concentration and pH level in relation to NaCl concentration. The increment of konjac concentration showed a positive effect to increase these protein properties, while the decreasing of the properties was evident when a high pH (pH 9) was applied. The variation of NaCl displaying slight effects on foaming properties and emulsifying activity of the proteins.The increment of konjac concentration from 0.1 to 0.5% significantly increased (p<0.05) batter flowability and consistency (viscosity), specific volume, textural characteristics (hardness, cohesiveness, chewiness and springiness) and lightness (L*) of gluten-free muffins. Moreover, sensory attributes including appearance, color, flavor, taste, texture and overall acceptance evaluated by a 9-point hedonic scale test demonstrated that the muffins with added konjac at 0.25 to 0.5% were more preferable with respect to the no added konjac, gluten-free muffin. However, the optimal gluten-free muffin which achieved by 0.25% konjac was low in protein content as compared with the control. Likewise, lower cutting forces were observed in gluten-free muffins with konjac addition at 0.25-0.5% in relation to the control after 8 day storage at room temperature ( 28 ± 2 °C).