Interfacial assembly of propylene glycol alginate-modulated dual-protein nanoparticles in alcohol-containing Pickering emulsions: role of oil volume fraction in β-carotene protection.

BACKGROUND: Alcohol-containing emulsions face severe colloidal instability because ethanol perturbs biopolymer conformation and interfacial organization. To overcome this, we fabricated ethanol-tolerant Pickering emulsions stabilized via the interfacial assembly of propylene glycol alginate (PGA)-modulated lactoferrin/zein (LZ) composite nanoparticles. This study systematically elucidated the role of the oil-phase volume fraction (φoil, 200-700 mL L-1) in regulating the physicochemical properties, rheological behavior, and β-carotene protection of these complex colloidal systems in an aqueous medium containing 150 mL L-1 ethanol.

RESULTS: The LZ-PGA particles formed particle-rich interfacial layers, conferring solid-like and thermally stable viscoelastic behavior. Increasing the oil fraction promoted droplet crowding and colloidal network formation, whereas excessive oil loading at 700 mL L-1 promoted droplet destabilization. The emulsion containing 600 mL L-1 oil showed the best physical stability and β-carotene protection, with enhanced resistance to thermal, ionic, photolytic, and storage stresses. This formulation reduced the photodegradation rate constant to 0.155 h-1 and extended the β-carotene half-life to 4.42 h, compared with 1.42 h for free β-carotene. During simulated digestion, β-carotene showed a biphasic release profile, and the highest bioaccessibility of 16.11% was achieved at 500 mL L-1 oil.

CONCLUSION: Oil fraction regulation provides a practical strategy to balance emulsion stability and bioactive delivery. The emulsion containing 600 mL L-1 oil is preferred for shelf stability and β-carotene protection, whereas that containing 500 mL L-1 oil is more suitable for digestive release and bioaccessibility. © 2026 Society of Chemical Industry.