Dispersed Phase and Emulsification Conditions on the Stabilit ...

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Premix emulsification is an important step for further fine emulsion preparation and emulsion stability. Process parameters, as well as interactions of ingredients, may significantly change the emulsion stability. In this study, refined olive oil was used as a continuous phase of w/o emulsion. The effects of the continuous phase amount, emulsifier rate, and mixing velocity at three levels on emulsion stability, viscosity, and zeta potential values were evaluated by using a response surface method with a central composite design. Minimum separated oil was found for the emulsions having 5 percent PGPR and 80 percent of olive oil, while the maximum was found 70 percent oil and 1 percent PGPR emulsion. Also the emulsifier rate, mixing velocity, square of emulsifier rate, square of mixing velocity, and interaction of oil phase % with the emulsifier rate were found significantly effective on emulsion stability (p<0.05). Emulsions prepared at minimum velocity had higher emulsion stability as it was referred in the model equation. Experimental results of separated oil % and viscosity were in accordance with the estimated results (R2=0.9938 and 0.9954) depending on regression analysis. For viscosity response, oil phase % and square of oil phase % was found statistically significant (p<0.05). Multimodal distribution of the droplet size was observed with an average Sauter mean diameter of 1.748µm for the most stable emulsion.