Demulsification of water-in-oil emulsions stabilized with glycerol monostearate-based oleogel by secondary surfactant to enhance saltiness perception

W/O Emulsion is reported to enhance the saltness perception, resulting in the NaCl reduction. But how other surface-active surfactants in the food matrix affect the saltness perception in the emulsion is still unclear. This study investigated the effect of eight secondary surfactants on the structural properties and saltiness perception of glycerol monostearate-based oleogel-stabilized emulsions (OGEs). The selected low-molecular-weight surfactants (sucrose fatty acid ester-SE, soy lecithin-SL, Span 80, Tween 80) markedly enhanced sodium release and saltiness perception in OGEs. SE- and SL-containing emulsions achieved the most rapid sodium release and strongest saltiness perception due to extensive droplet aggregation. In comparison, three protein-based surfactants (casein, pea protein, or soy protein) exhibited milder but significant effects on saltiness enhancement by promoting droplet growth and localized coalescence. During oral processing, OGEs were further emulsified into oil-in-water emulsions with smaller, more oil droplets, concentrating sodium in the aqueous phase. The sodium diffusion test confirmed that the secondary surfactants, especially low-molecular-weight surfactants, further increased the sodium diffusion rate, benefiting for the improvement of saltiness perception. This study provides new ideas for designing solid and semi-solid low-salt foods.