Arabinogalactan from Anacardium occidentale Exudate as a Natural Emulsifier: A Sustainable Approach to Nanoemulsion...

Oil/water nanoemulsions are effective systems for delivering hydrophobic compounds in aqueous media, provided that stable formulations are achieved. In this study, arabinogalactan extracted from Anacardium occidentale exudate was evaluated as a natural emulsifier for the production of nanoemulsions. Its performance was compared with that of guar gum, a widely used polysaccharide emulsifier. Nanoemulsions were prepared using spontaneous emulsification (magnetic stirring) and mechanical ultrahomogenization (Ultra-Turrax). The systems were characterized in terms of droplet size (DS), polydispersity index (PDI), zeta potential (ζ-potential), rheological behavior, and morphology by Transmission Electron Microscopy (TEM). Formulations produced by spontaneous emulsification with arabinogalactan (Ae4) showed droplet sizes below 40 nm, while guar gum systems (GGe4) presented sizes below 100 nm. Both systems exhibited PDI values lower than 0.5, indicating moderate to good homogeneity. A strong negative correlation (r < -0.8) was observed between polysaccharide concentration and droplet size, while a moderate correlation was found with ζ-potential, whose values close to neutrality (∼0 mV) suggest that steric stabilization is the dominant mechanism in arabinogalactan-stabilized systems. TEM analysis confirmed the nanoscale droplet size and revealed a more uniform distribution of Ae4 compared to GGe4, indicating improved stability. Notably, nanoemulsions stabilized with arabinogalactan remained stable for up to 70 days, with reduced droplet agglomeration over time compared to those stabilized with guar gum. These findings highlight the novelty of using arabinogalactan from A. occidentale as an efficient natural emulsifier. At higher concentrations and under spontaneous emulsification, it produces smaller droplets (up to ∼60% reduction) and enhances long-term stability. This polysaccharide represents a promising, safe, and sustainable alternative for applications in the food, cosmetic, and pharmaceutical industries.