Effect of protein content on emulsion stability of a model infant formula

The objective of this study was to examine the effects of lowering protein content of a model infant formula on its processing characteristics and physical stability. Formulations containing five different protein:fat ratios (0.21–0.43) were investigated. Increasing protein:fat ratio increased viscosity and decreased fat globule size. Fat globule size increased significantly upon evaporation (P < 0.05) for all formulations, but decreased significantly (P < 0.05) following atomization during spray drying. The specific surface area of fat globules increased with increasing protein:fat ratio, while protein load (τ) did not differ significantly between treatments. Increasing protein:fat ratio resulted in decreased creaming rates and improved emulsion stability. In conclusion, decreasing the protein:fat ratio of the formulae, particularly to 0.21, reduced the physical stability of the emulsions.