Ultrasound pretreatment of Acacia seyal gum arabic before spray drying: effects on interfacial behavior and avocado oil emulsion stability

High-intensity ultrasound can modify hydrocolloid functionality, but the processing conditions that improve gum arabic performance without impairing stabilization remain uncertain. This study evaluated a structured screening matrix in which gum arabic dispersions at 20–30% (w/w) were treated at nominal powers of 255–765 W for 0–15 min, spray dried, reconstituted to 20% solids, and used to stabilize avocado oil-in-water emulsions. Intrinsic viscosity, Cross-model rheology, time-resolved interfacial tension, gum-dispersion zeta potential, droplet-size evolution, and Turbiscan stability were evaluated. The intrinsic-viscosity-derived apparent hydrodynamic-size estimate decreased from 0.760 MDa in untreated gum to 0.663 MDa after 10 min, with little further average change after 15 min. Across the tested branches, 10 min gave the most favorable average interfacial and physical-stability response: mean interfacial tension at 1800 s decreased from 15.04 to 11.25 mN/m, the pre-drying gum-dispersion zeta potential shifted from −23.69 to −29.32 mV, and mean day-21 Turbiscan Stability Index decreased from 2.834 to 1.987. A branch-adjusted repeated-measures analysis supported an exploratory association between interfacial-tension reduction and increased zeta-potential magnitude (coefficient 0.938; 9 degrees of freedom; probability below 0.001). The endpoint-specific rankings were not identical: E-10 had the lowest day-21 Turbiscan Stability Index, whereas C-15 had the smallest final droplets. Thus, 10 min is interpreted as an operationally favorable average duration within the tested concentration–nominal-power matrix, not as a universal optimum or direct evidence of a molecular mechanism. The observed differences reflect the complete processing history, including ultrasound pretreatment, heating, spray drying, and reconstitution.