In this paper, the foaming and surface properties of sodium caseinate (SC), sodium caseinate/tannin acid (SC/TA), sodium caseinate/octenyl succinate starch (SC/OSA-starch), and sodium caseinate/tannin acid/octenyl succinate starch (SC/TA/OSA-starch) complex systems are described. First, foaming properties of different samples were compared at pH 6.0. The interface adsorption and linear surface dilatational rheological of different samples were characterized in the linear viscoelastic region to explore the relationship between macroscopic foaming properties and surface properties. At equal protein concentrations, the foamability and foam stability of the SC/TA/OSA-starch complex was markedly higher than that of the SC/TA complex. Meanwhile, the surface properties of the SC/TA/OSA-starch complex were also superior to those of the SC/TA complex. Finally, to investigate the nonlinear surface dilatational rheological behavior of the air/water interface stabilized by complex systems, the large-amplitude oscillatory dilatational rheology and Lissajous plots were studied. For the SC/TA/OSA-starch complex, the OSA-starch increases the degree of strain softening in extension, suggesting that the surface structure may change from a surface gel to a mixed phase of SC/TA patches and OSA-starch domains. These findings indicate that the complex formed between polyphenols, proteins, and polysaccharides could be used as a good alternative to understand and, consequently, improve the surface and foaming properties in food matrices.
Keywords: Lissajous plots; foaming properties; nonlinear surface rheology; sodium caseinate; surface dilatational modulus.