Interfacial arrangement of tunable gliadin nanoparticles via electrostatic assembly with pectin: Enhancement of foaming property

Gliadin nanoparticles (GNPs) have impressive foaming properties, but their foam capacity and stability are sensitive to acidic pH, due to inferior interfacial properties. To regulate the interfacial behavior, pectin was introduced to surface modulation of GNPs and its influence on the structure, interfacial properties, and macroscopic foaming performances of GNPs at a pH of 3.5–5.8 was discussed. Results exhibited that pectin and gliadin could form complex nanoparticles (GPNPs) at pH ranging from 3.5 to 5.8, mainly through electrostatic interaction. The half-life time of foam covered by GPNPs at pH 3.5 were about 160-fold larger than that of GNPs at the same pH. This was because the large GPNPs with irregular shape exhibited hard particle-like characteristic and could not deform at the interface, but interestingly, they closely arranged at the interface in a seemingly stacked way. This led to the high particle coverage and the formation of the steric barrier layer, which effectively prevented foam from disproportionation and coalescence. Besides, the unadsorbed GPNPs located at the Plateau borders could act as corks to slow down the drainage. With respect to GPNPs at pH 5.8, they displayed the deformable property at the interface and adjacent GPNPs could cross-linked by pectin to form a tight interfacial layer. GPNPs displayed high foamability, strong foam plasticity, and long-term stability simultaneously in a broad pH range, demonstrating that they can be utilized as an efficient foaming agent for fabricating foamed food.