Ultrasound-induced structural reorganization enhances gelation and stability of flaxseed gum emulsion gels.

Abstract

Flaxseed gum (FG) possesses the potential to stabilize emulsions without ions or additional gelling agents, but its limited intrinsic interfacial activity typically requires high concentrations to achieve adequate stability, resulting in coarse droplets, weak gel networks, and reliance on co-stabilizers. Whether the properties of FG can be sufficiently improved to serve as a stabilizer in emulsion gels remains unclear. To address this, the effects of ultrasound modification on FG emulsion gels were investigated under specific power-time treatment sequences to study the mechanisms of FG as a sole stabilizer. Ultrasound markedly improved functional properties: EAI increased from 15.07 to 26.23 m2/g at FG 0.8% (250 W/7 min) and from 14.88 to 30.23 m2/g at FG 1.2% (350 W/15 min). ESI rose from 144.97 to 463.44 min (FG 0.8%, 250 W/15 min) and 167.97 to 693.37 min (FG 1.2%, 350 W/15 min). WHC remained high (~95-99.7%), with maximal retention at FG 1.2%, 250 W/25 min. Particle size distributions indicated preserved macroaggregate structure, while FTIR suggests changes in molecular reorganization and possible enhancement in FG-oil interactions. LF-NMR showed reduced water mobility and stronger water-matrix interactions while XRD exhibited an amorphous gel nature indicating partial recovery of short-range order at higher power/time. Thermo-rheology revealed thermal reinforcement reaching the highest G' at the maximum temperature tested (85 °C) under 250 W/15 min. CLSM revealed refined droplet networks at moderate conditions, with partial recoalescence under prolonged high-power treatment. These results support the potential for ultrasound modified FG to function as a sole stabilizer in food-based gels.