Engineering hydrogel-in-oleogel bigels for reduced-fat and egg-free mayonnaise: relating phase architecture to...

Hydrogel-in-oleogel (HG-in-OG) bigels have attracted increasing interest as structured lipid systems for fat replacement, yet the relationships between their phase architecture and functionality in complex foods remain insufficiently understood. In this study, food-grade HG-in-OG bigels were prepared by combining phytosterol/γ-oryzanol oleogels with sodium alginate hydrogels at oleogel fractions ranging from 40% to 80%. Increasing the oleogel fraction progressively refined the dispersed hydrogel domains from 4.21 ± 1.57 μm to 1.77 ± 0.69 μm, accompanied by enhanced network rigidity, reduced molecular mobility, and reduced structural recovery after shear, while interfacial properties changed only marginally. The optimized bigels were subsequently incorporated into bigel-based mayonnaise with egg yolk (BGYM) and bigel-based yolk-free mayonnaise (BGYFM) to investigate the relationship between bigel phase architecture and mayonnaise functionality. All mayonnaise samples remained physically stable during 14 d of storage at 25 °C and exhibited gel-like viscoelastic behavior. Increasing the oleogel fraction markedly reduced the hardness of BGYFM from 1.15 N to 0.26 N, producing textural properties closer to commercial mayonnaise. Although the electronic nose differentiated the aroma profiles of the BG-based mayonnaise formulations, sensory odor responses were less pronounced, whereas overall acceptability varied with mayonnaise type and oleogel fraction. Among the tested formulations, 50BGYM and 60BGYM achieved the highest overall sensory score (7.85). Systematic variation of oleogel fraction was accompanied by coordinated changes in phase architecture, bulk material properties, and mayonnaise functionality, providing a structural basis for the rational design of potentially healthier structured lipid systems.