Stabilizing O/W Emulsions by Soy Protein Concentrate + Maltodextrin and Optimizing the Process by Using Response Surface Methodology

Abstract

Stability is one of the key quality parameters of emulsion systems, which goes a long way in predicting the shelf life of emulsion products. In this study, the effect of emulsifier (soy protein concentrate (SPC) + maltodextrin (MDX)), dispersed phase (lycopene in oil solution) and homogenizer speed on emulsion stability were investigated and optimized using response surface methodology (RSM). Independent variables were lycopene content (10-20%, w/w), SPC+ MDX as emulsifier and surfactant (30-40%, w/w) and the homogenizer speed (14000-18000 rpm). Responses were droplet size, viscosity and creaming index as stability indicators of the emulsions. According to RSM analysis and models, optimized variables showed a good fit to quadratic equations for droplet size and viscosity with correlation coefficients (R 2) of 0.9571 and 0.9826, respectively. After model simplification with backward stepwise solution, the R 2 values for droplet size and viscosity decreased slightly to 0.9504 and 0.9826, respectively. Creaming values were fitted properly with linear model, and R 2 was 0.8030. Graphical optimization methods were adapted for preparing the best lycopene emulsifying conditions and were predicted to be: homogenizer speed of 18000 rpm; lycopene content of 20% w/w, and SPC+MDX concentration of 36.95% w/w.