The formation, interfacial, and foaming properties of complex constructed by caseinate and soy protein nanoparticle

In this work, a kind of complex with preferable foaming properties was prepared by caseinate-soy protein nanoparticle (Cas-SPNP), and the effect of different Cas/SPNP ratios on the interactions, interfacial characteristics, and foaming properties was investigated. The complexation of Cas and SPNP in bulk occurred through hydrophobic interaction and hydrogen bonding. As the SPNP proportion increased from 9:1 to 7:3, the z-average size of the Cas-SPNP complex decreased by 29.80 nm, while the surface hydrophobicity (H0) increased from 13738 to 16226. Moreover, as compared with Cas, the dilatational modulus of the complex considerably increased by 2.93 and 2.13 times, indicating a more stable air-water interface of the Cas-SPNP complex than that of Cas. Meanwhile, the foaming ability and foam stability increased to 145 % and 74.07 %, respectively, indicating a beneficial influence of interfacial properties on the foaming properties. However, a higher proportion of SPNP (Cas/SPNP ratios ranging from 6:4 to 5:5) might disrupt the intramolecular interactions and lower the surface activity, which in turn decreased the foaming ability. In summary, foams prepared by Cas-SPNP complexes with a lower decay rate provided a new strategy for the foam stability problem of Cas.