Enhanced Saltiness Perception of Gum Arabic-Stabilized Emulsions through Improved Sodium Retention in the Salivary Layer

Salt reduction remains a critical challenge in oil-containing systems. We examined the influence of gum arabic (GA)-stabilized emulsions with varying oil contents (0.5, 1, and 2%) on saltiness perception. Saltiness perception was enhanced in all GA-stabilized emulsions compared with the GA solution, with the stable 1% GA-E exhibiting the strongest effect. This result may be attributed to the increased negative ζ-potential values, thereby promoting Na⁺ adsorption on droplet surfaces and leading to inhomogeneous Na⁺ distribution. GA exposed negatively charged hydrophilic groups at the oil-water interfaces, facilitating droplet-mucin interactions, as confirmed by mucin adsorption and quartz crystal microbalance with dissipation. These interactions also promoted the adhesion of droplets and Na⁺ to saliva, as demonstrated by in vitro adhesion and retention experiments. In contrast, the reduced saltiness of unstable 2% GA-E likely resulted from droplet destabilization and oil coating, which diminished mucoadhesion. This study provides valuable insights into saltiness mechanisms in emulsions.