Synergistic effect of edible salts on the physicochemical properties of whey protein isolate-carrageenan complexes and their application as foam and emulsion stabilizers

NaCl and CaCl₂ are commonly used edible salts in food. The synergistic influences of these two salts on the physicochemical properties of whey protein isolate-carrageenan (WPI-Car) complexes were investigated in relation to their foaming and emulsifying properties. The results showed that as the ratio of NaCl: CaCl₂ decreased from 6:0 to 3:3, the turbidity of the complexes increased from 0.51 to 0.77 and the absolute zeta potential decreased from 28.86 to 9.05 mV (P < 0.05). NaCl caused the exposure of hydrophobic groups, whereas CaCl₂ caused hydrophobic groups to be buried within the molecule. The transformation between the α-helix structure and β-sheet structure of WPI was closely related to the ratios of NaCl to CaCl₂. The electrostatic force, hydrophobic interaction, and hydrogen bond were significantly influenced by the synergistic influence of NaCl and CaCl₂. The foaming capacity of WPI-Car complexes reached a maximum of 90.0 % at a NaCl: CaCl₂ ratio of 3:3. Compared to the individual effects of monovalent NaCl and divalent CaCl₂, the mixture of NaCl and CaCl₂ (5:1) produced suitable refolding due to their synergistic effect, which improved the emulsifying properties of WPI-Car complexes. The findings of this study provide useful information for designing and preparing WPI-Car complexes for food applications.