The effect of pH and high-pressure processing (HPP) on the rheological properties of egg white albumin and basil seed gum mixtures

In this study, the effect of two different pH's (5.0 and 7.0) and three different levels of high-pressure processing (HPP; 0, 200, and 400 MPa) on the rheological properties of the mixture solutions of egg white albumin (4% w/v EWA) and basil seed gum (0.3% w/v BSG) was investigated. A shear thinning behavior was observed in all of the EWA-BSG mixtures. Herschel-Bulkley and Carreau were selected as the best models for describing the flow behavior data in the mixtures made at pH 7.0 and 5.0, respectively. All of the viscoelastic parameters (i.e. G'(LVE), G ''(LVE), tan (delta)(LVE), and tau(f)) indicated a stronger structure at the highest pressure (400 MPa) and the lower pH (5.0). The value of material stiff parameters (A(alpha)) indicated that pH 5.0 resulted in a higher amount of molecular binding between EWA and BSG. Relaxation function (alpha) decreased with increase in pressure level, meaning that a greater degree of the possible interactions happened at the higher pressure. None of the EWA-BSG solutions followed Cox-Merz rule. The temperature of reinforcement of the gel network (T-r) in the EWA-BSG mixtures decreased from similar to 66 degrees C at pH 7.0-similar to 55 degrees C at pH 5.0, and the storage modulus of the mixtures varied depending on the pH. The highest complex viscosity (after heating step) belonged to the sample prepared at pH 5.0 and treated with 400 MPa. Overall, it was found that HPP, alone or combined with pH treatment, could improve the structure of the egg white albumin and basil seed gum mixtures.