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 ( φ oil , 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.