Air-water interfacial and foaming properties of crude and purified globulins from pigeon pea seeds

Protein concentrates or isolates are widely used by the food industry to produce aerated foods. Although the foamability is primarily attributed to proteins, highly surface-active minor compounds are also present in these ingredients, and their presence must be considered when investigating their air-water interfacial properties. In this study, the air-water interfacial and foaming properties of crude and purified globulin extracts from pigeon pea seeds were evaluated. At low bulk concentration, no difference in the interfacial behavior was observed between crude and purified globulins. At high bulk concentration, crude globulin extracts formed less rigid interfacial films compared to purified globulins, with the latter leading to viscoelastic solid-like interfacial layers. This suggests that in more concentrated suspensions, minor compounds of the crude extracts accumulate more at the interface, competing with globulins for adsorption, which leads to a reduction in the mechanical rigidity of the interfacial film. Purified globulins demonstrated superior aqueous foam stability compared to whey protein isolate and bovine serum albumin, highlighting the potential of pigeon pea globulins as effective foaming agents in food applications.