Fabrication and characterization of W/O emulsion stabilized by instantly soluble agar-leucine Maillard conjugates

Water-in-oil (W/O) emulsions exhibited significant potential as fat replacers in low-fat condensed colloidal foods, such as mayonnaise, without compromising sensory attributes. In this study, an instantly soluble agar-leucine Maillard conjugate (ALM) was synthesized and demonstrated exceptional emulsification capacity, stabilizing W/O emulsions containing 90 % (v/v) oil phase at a remarkably low concentration (1 %, w/v). Zeta potential analysis indicated a net surface charge conferred by ALM, while microscopic and cryo-scanning electron microscopy (cryo-SEM) characterization revealed dual stabilization mechanisms. Under ambient conditions, ALM functioned as an amphiphilic emulsifier, reducing interfacial tension and adsorbing at the oil-water interface to form a cohesive interfacial film, while simultaneously generating electrostatic repulsion to prevent droplet coalescence. Under refrigerated conditions, ALM interacted with water molecules to establish a three-dimensional gel network, immobilizing dispersed aqueous droplets within the continuous oil phase and suppressing gravitational phase separation. Sensory evaluation of reduced-fat semi-solid mayonnaise formulated with ALM showed texture, mouthfeel, and overall acceptability comparable to full-fat counterparts, validating its efficacy as a natural alternative to hydrogenated oils. This work highlighted the dual functionality of ALM as both an emulsifier and cryostabilizer, offering a novel strategy for designing clean-label, low-fat food systems as multifunctional emulsion ingredients.