Effect of combining ultrasound with pH shifting on adsorbed layer formation by pea proteins

The focus of this paper is on the impact of approaches used to improve protein solubility on its interfacial activity. A range of approaches are used to disperse vegetable proteins in water to stabilize emulsions. Applying physical fields like sonication while pH shifting is thought to have synergistic effects on the emulsifying activity of plant proteins. But the key structural features of proteins that are altered by modification and affect adsorbed layer formation remain unclear. This study evaluated the effects of combining pH shifting and ultrasonication on the interfacial properties of pea proteins. Droplet profile tensiometry and interfacial rheometry were used to compare the adsorption kinetics and interfacial shear moduli of layers formed by pea proteins before and after modification. The first key result is that adsorption and layer formation by the protein are slower in the modified dispersions. This is due to a decrease in the level of disorder in the secondary structure of the protein. The second key result is that layers formed by the modified protein are less elastic due to a reduction in the number of thiol groups available to form connections between molecules. These findings advance our understanding of how increasing protein dispersion can alter the protein structure and hence its interfacial activity.