Effect of high-pressure homogenization on the foaming properties of cowpea (Vigna unguiculata L. Walp.) protein isolate

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The growing demand for sustainable protein sources has increased interest in plant proteins with suitable techno-functional properties for aerated food systems. Cowpea (Vigna unguiculata L. Walp) stands out due to its high protein content and socioeconomic relevance in Brazil, although structural limitations may impair its foaming performance. This study evaluated the effect of high-pressure homogenization (HPH; 60, 100 and 140 MPa; 1-3 cycles) on the physicochemical, interfacial, physical stability, and foaming properties of cowpea protein isolate. The isolate was obtained by saline extraction at pH 8.0 followed by dialysis, yielding high protein content (94.92%). HPH preserved the electrophoretic profile of the proteins but significantly reduced particle size, while zeta potential remained largely unchanged. Surface hydrophobicity and solubility were affected by processing conditions, and solubility exhibited the typical U-shaped profile as a function of pH. Interfacial analyses revealed increased protein diffusion and adsorption rates at the air-water interface, higher equilibrium surface tension, and greater interfacial elasticity, indicating the formation of more cohesive and mechanically resistant interfacial films. Although physical stability and foam stability were not significantly affected by HPH, all samples exhibited high foam stability (87-96%). Foaming capacity was significantly enhanced by processing and reached its highest value at 140 MPa for 3 cycles (46.43%). Correlation analysis indicated that particle size reduction and improved interfacial mobility were among the main factors contributing to the enhanced foaming performance. Overall, HPH, particularly at 140 MPa for 3 cycles, proved to be an effective strategy to improve the foaming functionality of cowpea protein isolate, supporting its potential application as a sustainable ingredient in aerated food products such as mousses, whipped desserts, milkshakes, and foamed beverages.