Modeling the Rheological Properties of Carboxymethylcellulose Stabilized O/W Emulsions Based on Sunflower Oil and Tallow Fat

The aim of this research was to assess the effect of fat type and concentration as well as the continuous phase viscosity on the rheological properties of an oil-in-water (O/W) emulsion. Thus, sunflower oil and tallow fat were used as the dispersed phase of the emulsion both at 10 and 50% (w/v) and CMC solutions (at 0.1, 0.3 and 0.5% w/v) were acted as the continuous phase. CMC solutions and emulsions showed a shear-thinning behavior with increasing CMC or dispersed phase concentration. The rheological behavior of all samples was well modeled by Herschel-Bulkley, Power law and Casson equations. According to Herschel-Bulkley and Power law models, an increase in the consistency index and a decrease in the flow behavior index of all samples was occurred with increasing CMC concentration (0.1 to 0.5%), fat concentration (10 to 50%) and dispersed phase change from liquid oil to a solid fat. The obtained data were compared with Einstein, Larson, Pal and Dougherty-Krieger predicting models and the results showed that Larson model well described the flow behavior of emulsions with 10% fat content, and Dougherty and Krieger or Pal equations were fitted more with the experimental data of emulsions containing 50% fat content.