Multimodal distribution of the droplet size was observed with an average Sauter mean diameter of 1.748µm for the most stable emulsion. For viscosity response, oil phase % and square of oil phase % was found statistically significant (p<0.05). The measurement of static physico-chemical properties of oil-water interfaces provides a useful method of indicating where problem emulsion stability areas. The oil and water mixed much better when the egg yolk was added. Students may observe colloidal mixtures in the other bottles, but they are not oil and water emulsions and two separate layers should be clearly seen. Detergent, egg yolk and mustard are emulsifiers, the others are not. Experimental results of separated oil % and viscosity were in accordance with the estimated results (R2=0.9938 and 0.9954) depending on regression analysis. An emulsifier is a substance that stabilises an emulsion. Emulsions prepared at minimum velocity had higher emulsion stability as it was referred in the model equation. All emulsions were prepared according the Emulsion Phase Inversion (EPI) method, where the water and oil phases were heated separately at 75C, the water phase was added into the oil phase (rice bran oil and surfactants) while stirring at 600 rpm (Fisatom, 713-Dmodel, Brazil), and the mixture was then cooled to 25C while stirring. 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). 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. 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. In this study, refined olive oil was used as a continuous phase of w/o emulsion. This effect is explained with a mass transfer of molecules between the aqueous and the oil phases which keeps the oil films out of equilibrium for a long period. Process parameters, as well as interactions of ingredients, may significantly change the emulsion stability. Premix emulsification is an important step for further fine emulsion preparation and emulsion stability.
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