Rheological and Stability Evaluation of Emulsions Containing Fenugreek Galactomannan—Xanthan Gum Mixtures: Effect of Microwave and Ultrasound Treatments

Abstract

The effects of treating two biopolymers (Trigonella foenum—graceum galactomannan and xanthan gum mixtures) with microwaves and ultrasound on the rheological aspects of O/W emulsions were investigated. The data obtained from steady shear flow were fitted with various models and the best were chosen due to the values of R2 and RMSE. The oscillatory shear rheology data demonstrated that the emulsions not treated with microwaves or ultrasound had viscous-like behavior and treated samples demonstrated weak gel behavior. The values obtained for various rheological parameters (especially apparent viscosity, storage modulus and loss modulus) indicated that fenugreek galactomannan had more impact on the rheological aspects of emulsions in comparison with xanthan gum. In addition, the synergistic interaction between two biopolymers, particularly in samples treated with ultrasound, resulted in better rheological aspects which could be affiliated with the strong bonds between the hydrocolloids. By treating the samples with microwaves and ultrasound, the emulsion stability values of the samples (especially those with a high ratio of galactomannan) significantly increased, which might be connected with various parameters, especially viscosity.