Mesquite-Derived Galactomannan Esters as Novel Oleogelators: Emulsion Characteristics and Their Emulsion-Templated Oleogels

This study investigates the emulsifying capacity (EC), emulsion stability (ES), and oleogel-forming potential of galactomannan (GM) esters modified with decanoic (GD) and palmitic (GP) fatty acids at low (L) and high (H) degrees of esterification (DE) (GDL, DE 0.37; GDH, DE 0.71; GPL, DE 0.47; GPH, DE 0.57). Oil-in-water (O/W) emulsions (6, 8, and 10% w/v) of native GM and GM esters were prepared and characterized for droplet size, ζ-potential, and rheological behavior. Esterified GMs demonstrated improved EC compared to native GM, especially at higher concentrations and lower DE. All emulsions exhibited non-Newtonian and pseudoplastic behavior, with the GDH and GPL samples showing gel-like viscoelastic profiles (G′ > G″). Emulsions were freeze-dried to form oleogels, which were then analyzed for oil-binding capacity (OBC), hardness, chemical interactions (FTIR-ATR), and microstructure (SEM). The GDH and GPL oleogels exhibited higher OBC (59–73%) and lower hardness, which can be attributed to denser polymer–oil networks and enhanced hydrophobic interactions. SEM analysis further confirmed that esterification improved the microstructural integrity of emulsion-templated oleogels. These findings support the potential of mesquite GM esters as amphiphilic oleogelators for the formulation of structured lipid systems, offering valuable applications in food and pharmaceutical industries seeking solid fat alternatives.