Interfacial and emulsifying properties of β-conglycinin/pectin mixtures at the oil/water interface: Effect of pH

The influence of pH (2–7) on the interfacial and emulsifying properties of β-conglycinin/pectin (7S/PC) mixtures was investigated. At pH 2–3 (pH < pI of 7S), 7S/PC mixtures had large size and low Zeta potential, leading to slower adsorption kinetics. When treated by deformation amplitude in the non-linear region, Lissajous plots of 7S/PC mixtures at pH 3 suggested that PC might adsorb onto the interfaces through competitive adsorption as proved by viscous behavior response. These combinations effects resulted in poor emulsification properties and emulsions instability. At pH = 5–7 (pH > pI of 7S), 7S/PC mixtures had smaller size and higher Zeta-potential values, leading to the rapid adsorption. Lissajous plots of 7S/PC mixtures at pH 6 suggested that 7S almost irreversibly adsorbed onto the interface as proved by a purely elastic response. Particle sizes of emulsions stabilized by 7S/PC mixtures at pH 6–7 remained unchanged due to that PC provided electrostatic and steric stabilization. In summary, pH had significant effects on the interactions between 7S and PC, and thereby influenced the interfacial and emulsifying properties of their mixtures. • pH affected the interfacial and emulsifying properties of 7S/PC mixtures. • 7S/PC mixtures facilitated emulsion stability at pH 6–7 but emulsion instability at pH 2-3. • Lissajous plots of 7S/PC mixtures at pH 3 suggested competitive adsorption of PC. • Lissajous plots of 7S/PC mixtures at pH 6 suggested irreversible adsorption of 7S.