Relationship between White Kidney Bean (Phaseolus vulgaris L.) Proteins and Emulsion Stability

To explore the relationship between the structural characteristics of white kidney bean proteins and the stability of white kidney bean milk, this study compared the protein structure, composition and physicochemical properties of eight cultivars of white kidney bean (WK1–WK8). After enzymatic hydrolysis, we investigated changes in protein solubility, emulsifying activity and secondary structure. Furthermore, we clarified the mechanism of action of proteins in emulsion systems. Results showed that WK1, WK2 and WK3 white kidney bean milks contained highly hydrophilic proteins and exhibited uniform microstructures, and proteins and lipids were well distributed in them. In contrast, the microstructure of WK4–WK8 exhibited large particle aggregates, the continuous phase was disrupted and the emulsion stability was poor. Protein hydrolysates from WK1–WK3 displayed significantly higher emulsifying activity and solubility compared to those from WK4–WK8. The elevated protein solubility was beneficial for improving both emulsion stability and sensory attributes. These findings not only provide a theoretical basis for selecting white kidney bean cultivars and optimizing the processing conditions for plant-based milk analogues but also offer insights for the application of other high-protein plant materials in emulsion systems.