Preparation of Lycopene Emulsions by Whey Protein Concentrate and Maltodextrin and Optimization by Response Surface Methodology

Abstract

In this investigation, response surface methodology (RSM) was used to optimize preparation of lycopene emulsions. To do this, lycopene content (10–20%, w/w), amount of whey protein concentrate (WPC) + maltodextrin (MD) (30–40%, w/w), and homogenization speed (14000–18000 rpm) were considered as independent variables and droplet size, viscosity, and creaming index of the emulsions were considered as dependent variables. Results showed that droplet size and viscosity could be adequately fitted into quadratic models with multiple regression coefficients of 0.9763 and 0.9957, respectively; however, creaming index was fitted with linear model and a regression coefficient of 0.8670. According to the RSM equations, the linear term of all three independent variables and the quadratic term of homogenization speed had significant effect on the droplet size of emulsions; while viscosity was significantly affected by the linear term of the independent variables plus the quadratic term of WPC + MD concentration, interactions between homogenization speed and WPC + MD, and interactions between lycopene content and WPC + MD concentrations. Also, all three independent variables significantly affected creaming index of emulsions. The graphical optimization method was adapted to find the best emulsifying conditions and it was predicted that the optimum conditions for preparation of lycopene emulsions would be at homogenization speed of 18000 rpm, lycopene content of 18.85% w/w, and WPC + MD concentration of 37.16% w/w.