Effect of Arabic gum, xanthan gum and orange oil contents on ζ-potential, conductivity, stability, size index and pH of orange beverage emulsion

The main and interaction effects of main emulsion components namely Arabic gum content (13-20%, w/w,x(1)), xanthan gum content (0.3-0.5%, w/w, x(2)) and orange oil content (10-14%, w/w, x(3)) on beverage emulsion characteristics were studied using the response surface methodology (RSM). The physicochemical properties considered as response variables were: zeta-potential (Y-1), conductivity (Y-2), emulsion stability (Y-3), size index (Y-4) and pH (Y-5). The results indicated that the response surface models were significantly (p < 0.05) fitted for all response variables studied. In contrast with zeta-potential and pH, the independent variables had the most significant (p < 0.05) effect on size index. Regression models describing the variations of the responses variables showed high coefficient of determination (R-2) values ranging from 0.866 to 0.960. The main effect of Arabic gum followed by its interaction with orange oil was observed to be significant (p < 0.05) in most of response surface models. Therefore, the concentration of Arabic gum should be considered as a critical variable for the formulation of orange beverage emulsion in terms of the emulsion characteristics studied. The overall optimum region resulted in a desirable orange beverage emulsion was predicted to be obtained by combined level of 10.78% (w/w) Arabic gum, 0.24% (w/w) xanthan gum and 12.43% (w/w) orange oil. No significant (p > 0.05) difference was found between the experimental and predicted values, thus ensuring the adequacy of the response surface models employed for describing the changes in physicochemical properties as a function of main emulsion component contents. (C) 2007 Elsevier B.V. All rights reserved.