Study of dextrin addition on the formation and physicochemical properties of whey protein-stabilized emulsion: Effect of dextrin molecular dimension

Oil-in-water (O/W) emulsion was prepared using whey protein as a natural emulsifier, and dextrin was incorporated with the emulsion formation. Dextrins with varying molecular dimensions (from 21.6 to 101.3 nm) were obtained by controlled enzymatic hydrolysis with alpha-amylase. The effects of molecular dimension of dextrin on the formation, stability, and physicochemical properties of the emulsions were then analyzed, by measuring their visual appearance, microstructure, particle size, zeta-potential, and rheological properties. Moreover, the environmental stress was assessed by temperature, pH, and ionic strength. The results indicated the presence of dextrin did not adversely affect the formation of small oil droplets during homogenization and the short-term stability of O/W emulsion. While in long-term storage, the emulsion with large dextrin and starch molecule was unstable to aggregate, and small dextrin could cooperate well in stabilizing the oil droplets in the emulsion system. A shear-thinning behavior was observed in all emulsions, and an increase in the emulsion viscosity (from 2.1 to 7.7 mPa.s) was examined with the addition of dextrin. Environmental stress of emulsion with low dimension dextrin was determined, indicating it was relatively thermal-stable. And some aggregations were found in emulsions near pH 4 and 5, as well as with NaCl addition. These results suggest that whey protein with low dimension dextrin addition may be a useful emulsifier for utilization within the food industry.

Automated summary

Whey protein was used as a natural emulsifier to prepare oil-in-water emulsion with the incorporation of dextrin. The effects of dextrin's molecular dimension on the stability and rheological properties of the emulsion were analyzed. The results showed that small dextrin could stabilize the emulsion, while large dextrin caused instability and aggregation.