Insights into microalgae residue-derived protein-polysaccharide complex as a plant-based egg white foam alternative: chemical characteristics and interfacial behaviors.

Spirulina residues contain various active substances, but is often discarded. In this study, Spirulina residues extract (SWE) demonstrated excellent foaming properties, with a foam overrun of 6.91 L/L, surpassing egg white and other plant proteins. SWE is a polysaccharide-protein complex rich in nonpolar amino acids and has a loose secondary structure dominated by β-sheets and turns. Its high-molecular-weight polysaccharides, primarily composed of glucose, rhamnose, and fructose, form a fibrous network around proteins, promoting rapid adsorption at the air-water interface. The polysaccharides enhance membrane viscosity and foam stability. Sponge cakes partially or fully prepared with SWE showed comparable color and texture to those made with egg white. SWE shows great potential as a plant-based egg white substitute in products like plant-based eggs and creams, enabling high-value utilization of waste and reducing costs in the microalgae industry.