Effects of Water Soluble Materials on Water-in-oil Primary Food Emulsion Stability

Abstract

Water-in-oil (w/o) primary food emulsions are often used for encapsulation of bioactive food ingredients or preparing multiple emulsions, however there is a lack of study about evaluation of stability of these emulsions by adding food materials in the dispersed phase. In this study, water-in-olive oil emulsions were prepared with using different dispersed phases; maltodextrin (MD), whey protein isolate (WPI) and maltodextrin+whey protein isolate (MD+WPI) mixture (1:1 w/w) solutions were used at different rates to determine the effects of dissolved material on physical, chemical, rheological and thermal properties of the emulsions. The kinetic stability of emulsions were significantly improved with increasing rates of soluble materials (p<0.05), however the improvement was much clearer in emulsions with MD and WPI. The electrical conductivity of emulsions gradually decreased with the increasing amounts of soluble materials and the lowest conductivity was observed for the emulsion with 16% MD+WPI. Newtonian flow behaviour was observed for all of the emulsions, and the viscosity decreased with increasing amounts of dissolved material. The freezing and melting profiles of emulsions were found different than pure olive oil. The average freezing peak temperatures as well as the freezing and melting enthalpies of emulsions were higher than olive oil, but there was no clear difference observed depending on the amount or type of dissolved material. Average d43 values were found changing between 0.855-2.793 ?m and the lowest polydispersity was obtained when MD+WPI mixtures were used as the dispersed phase at 16% level.