Synergistic effects of Tremella polysaccharide and sodium caseinate: a promising strategy for regulating water distribution in fat-replaced foods

• The synergistic modification enhanced emulsion stability. • TFPS-SC inhibited the accumulation of oil in emulsion. • The water binding capacity of the TFPS-SC complex is significantly stronger. • TFPS-SC could be served as a feasible alternative to fat based on their interaction. • Reveals the distribution of moisture in emulsion and interaction between TFPS and SC. This study investigated the synergistic effect of Tremella polysaccharides (TFPS) and sodium caseinate (SC) at different ratios on water distribution in emulsions. The stability and rheological properties of the emulsion were analyzed and compared to a control group without TFPS. Results indicated that the TFPS-SC emulsion had a smaller particle size (132.6-452.47 μm), with a maximum emulsification activity index of 36.08 m 2 /g at 1:1 ratio of TFPS to SC. Additionally, the TFPS-SC emulsion at a ratio of 2:1 exhibited the highest zeta potential of -39.4 mV and the highest emulsification stability index of 65.31 min. The interaction between TFPS and SC in aqueous solutions was characterized by using turbidity measurements, confocal laser scanning microscopy, surface hydrophobicity, and spectroscopy. The molecular forces involved in the interaction between TFPS and SC were also examined. Low field nuclear magnetic resonance and magnetic resonance imaging studies have demonstrated that TFPS/SC can enhance the water holding capacity of emulsions, increase the accumulation of bound water, reduce the release of free water, and maintain a relatively high hydrogen proton density to retain water. TFPS-SC strongly bind to lipids, which could inhibit oil digestion and decomposition, showing the potential to be a feasible alternative to fat. These findings are significant for the regulation of TFPS and SC in food applications, especially fat replacement in foods.