Tuning bigel performance via emulsifier type and concentration: Structural, physicochemical, and molecular...

To develop bigels with tunable physical properties and enhanced chemical stability, this study investigated the effect of emulsifier type and concentration on the physical properties, microstructure, and oxidative stability of bigels composed of ethyl cellulose oleogel and deacetylated konjac glucomannan hydrogel. The marked improvement in bigel uniformity and dispersion observed at low concentrations (≤1 %) of glycerol monooleate (GM) and phosphatidylcholine (PC) was primarily attributed to the significant reduction in oil-water interfacial tension (from 18.10 to 12.90 mN/m). At concentrations of 0.5 %-5 % GM and 0.5 %-1 % PC, the oil binding capacity of the bigels increased by at least 2.40 % and 3.70 %, respectively, accompanied by an improvement in elasticity. However, with increasing GM and PC concentrations up to 5 %, the bigel hardness markedly decreased by 59.10 % and 72.10 %, respectively. Oxidative stability tests revealed that both emulsifiers effectively inhibited lipid oxidation after 21 days of storage, with maximum reductions in peroxide value of 69.02 % for GM and 59.76 % for PC; GM consistently showed superior antioxidant effects across all tested concentrations. Furthermore, molecular dynamics simulations revealed that electrostatic energy dominated bigel component binding, while van der Waals interactions were extensive and governed structural packing. The presence of GM or PC further strengthened intermolecular interactions within the bigel matrix. These results collectively demonstrate that emulsifier type and concentration can be strategically used to tune bigel performance, providing theoretical and practical insights for designing structured materials. The ability to modulate texture (hardness, elasticity) and enhance stability (oil binding capacity, oxidative resistance) is critical for their potential application as functional fat replacers in foods.