Improving the stability of fish gelatin emulsion by microbial transglutaminase and selected polysaccharides in a steady state

This study investigated the enhancement of fish gelatin (FG) emulsion stability by microbial transglutaminase (MTG) and three selected polysaccharides including konjac glucomannan (KGM), sodium alginate (SA) and guar gum (GG). Notably, a low-temperature (4°C) incubation strategy was used to promote compact wall formation, while parallel experiments at 50°C and non-crosslinked systems served as controls. The results showed that MTG-polysaccharides significantly improved the stability of FG emulsion in a steady state of 4°C. The synergistic combination of MTG-SA at 4 °C observably improved the storage stability of FG emulsion, achieving a 224-fold extension from 9 h to 28 d (672 h) under the ambient temperature. Correspondingly, MTG-SA co-modification at 4 °C enhanced FG emulsion ESI by 139.5%, while MTG-GG improved EAI by 34.6% under identical conditions. Regardless of polysaccharide types, MTG-polysaccharides at 4°C made FG emulsion the highest apparent viscosity. Three selected polysaccharides markedly reduced FG emulsion droplet size, meanwhile MTG-polysaccharides at 4°C increased absolute zeta potential values, indicating enhanced electrostatic interaction. Furthermore, MTG-polysaccharide co-modified FG emulsions exhibited superior water-holding capacity and surface hydrophobicity, with visibly uniform droplet distribution. In summary, co-modification of three selected polysaccharides (particularly SA) and MTG at 4 °C could significantly improve the stability of FG emulsion. • KGM, SA, GG and MTG treatment at 4°C both improved the stability of FG emulsion. • FG emulsion modified by SA and 4 °C MTG showed a stable state at 28 days. • KGM, SA, GG and MTG treatment at 4 °C made FG emulsion good EAI, ESI, WHC and surface hydrophobicity. • The schematic model was established for FG emulsion modified by KGM, SA, GG and MTG.