Selective enhancement of fish gelatin emulsification via structural compatibility with sodium alginate: A comparative...

This study systematically investigated the structure-dependent interactions between sodium alginate (SA) and three distinct proteins-fish gelatin (FG), soybean protein isolate (SPI), and whey protein isolate (WPI)-to elucidate their differential emulsification enhancement mechanisms. Mechanistic studies showed that FG exhibited unique structural compatibility with SA, driven by strong electrostatic interactions (ΔH = -6.59 kJ/mol, ΔS = 5.9 J/(mol·K)) and conformational flexibility from its linear polypeptide backbone. SA increased FG's emulsifying activity (EAI) by 108.7 % and stability (ESI) by 53-fold, outperforming SPI (31.4 % EAI increase) and WPI (21.3 % EAI increase). The constructed FG-SA composite emulsion system exhibited excellent overall performance, characterized by a uniform droplet size distribution (3.11 μm - 5.53 μm), markedly improved storage stability (> 7 d), and ideal rheological properties and water retention capacity. This study not only elucidates the dynamic mechanism of polysaccharide-protein synergistic stabilization of emulsions at the molecular level but also provides a key theoretical basis for developing functional emulsions.