Improvement of solubility, emulsification property and stability of potato protein by pH-shifting combined with microwave treatment and interaction with pectin

The application of potato protein (PP) in food industry has been limited due to its low water solubility, poor emulsification and stability. Herein, it was found that the pH-shifting combined with microwave heating significantly increased the solubility of PP (from 24.0% to 89.0%) and surface hydrophobicity (from 125 to 207). The particle size of PP was significantly reduced (from 249.95 ± 1.15 mm to 90.37 ± 1.03 nm). SDS-PAGE analysis indicated that the microwave treatment did not disrupt the primary structure of PP. A complex formation between modified potato protein (MPP) and pectin (PC) at the optimum mass ratio of MPP to PC of 4:1 and pH 5 was characterized by fluorescence spectroscopy, fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy, which showed that MPP and PC had electrostatic interaction. Moreover, the effect of mass ratios of MPP to PC from 5:1 to 1:2 on the phase behavior of MPP-PC soluble complexes was evaluated by the phase diagram and ζ-potential measurement. These results showed that the dispersibility, emulsification and thermal stability of the protein were improved by forming MPP-PC complexes. This study provides a valuable reference for the improvement of physicochemical and functional properties of PP which is conducive to broaden the application of the protein in food industry.