Bioactive food foams stabilized by licorice extract/whey protein isolate/sodium alginate ternary complexes

Abstract

Interactions among multi-component food matrices play a key role in modulating the foam properties. In this study, foams containing mixtures of sodium alginate (ALG; 0.5, 1.0, and 1.5% w/v), whey protein isolate (WPI; 0.2 and 0.6% w/v), and licorice extract (LE; 0.1, 0.3, and 0.5% w/v) were formed and characterized. The interactions between the components were confirmed by turbidity, ζ-potential, particle size, Fourier transforms infrared spectroscopy, and sodium dodecyl-sulphate gel electrophoresis. The pre-foam dispersions adopted a shear-thinning behavior with high apparent viscosity as a function of ALG level. Surface tension results indicated that ALG and LE were the main components at the air/water interface, and the pre-foam dispersions possessed a good antioxidant activity (up to 56.53%). The ALG/WPI/LE foamed systems had up to 446.03% overrun, up to 81.69% air-volume fraction, and up to 40.80 h physical stability. Foams with higher overrun and air-volume fraction displayed greater firmness and cohesiveness, as well. Additionally, the elastic properties (Gʹ) were superior to the viscous ones (Gʹʹ) at all frequency range which indicated the solid-like behavior of the foams. A remarkable free radical scavenging activity (up to 49.66%) was also observed in the foams. Therefore, the bioactive foams with high foamability, stability, and viscoelasticity could be used to design novel healthy aerated foods with low calorie content.