Valorization of Acacia tortilis extracts for stable oil-in-water emulsions with bioactive properties

Natural emulsifiers such as gum arabic face limitations including restricted availability, batch variability, and lack of intrinsic bioactivity. This study evaluated Acacia tortilis subsp. raddiana leaves, seeds, and pods as renewable sources of multifunctional emulsifiers. Hydroethanolic extracts (0–100% ethanol, v/v) were characterized for phenolics, flavonoids, saponins, proteins, and carbohydrates, linking composition to interfacial and biological functionality. Extracts reduced soybean oil–water interfacial tension from ∼65 to ∼40 mN/m at equilibrium, forming 10% (v/v) oil-in-water emulsions with droplet sizes of 80–320 nm and zeta-potentials of −29 to −50 mV. Aqueous seed and pod extracts yielded the smallest droplets, while ethanol-rich leaf extracts produced the most stable systems. FTIR analysis indicated adsorption of polysaccharides, saponins, and phenolics at the interface, supporting cohesive film formation. Extracts exhibited strong antioxidant activity (DPPH IC 50 = 0.12–2.46 μg/mL) and antibacterial efficacy (MIC = 0.25–1.5 mg/mL) against Pseudomonas aeruginosa and Enterococcus faecalis , with emulsions retaining partial activity (MIC = 1.0–2.0 mg/mL). The study highlights A. tortilis as a clean-label emulsifier integrating physical stabilization and bioactive protection, offering a functional alternative to gum arabic. These findings provide a framework for valorizing desert biomass into sustainable food, nutraceutical, and cosmetic ingredients. • Comparative extraction of leaves, seeds, and pods of Acacia tortilis subsp. raddiana. • Solvent polarity tuning revealed distinct composition–function relationships. • Aqueous seed/pod extracts produced smallest droplets (≈80–125 nm, ζ ≈ -34 to -44 mV). • Ethanol-rich leaf extracts enhanced emulsion stability and interfacial elasticity. • Extracts and emulsions showed strong antioxidant and antibacterial activities.