Abstract: In this study, a passion fruit seed oil Pickering emulsion stabilized by β-lactoglobulin nanoparticles loaded with a ternary mixture of ferulic acid, quercetin and vanillic acid (β-LGCNPs) was prepared by an ultrasonic method. The particle size, stability, and microstructure, and antioxidant, digestibility, rheological properties and lipid oxidation products of Pickering emulsions prepared under varying conditions of nanoparticle concentration and oil phase ratio were investigated. The results showed that the Pickering emulsion was a stable oil-in-water (O/W) emulsion with β-LGCNPs adsorbed at the oil-water interface. The particle size of the emulsion was directly proportional to the particle concentration and inversely proportional to the oil phase ratio. The average particle size of the Pickering emulsion prepared at β-LGCNP concentration of 1.5% and 30% oil phase was (5.78 ± 0.10) μm. The emulsion had good stability under different ionic strength and pH conditions, showing stronger antioxidant properties than passion fruit seed oil. The free radical scavenging capacity was dependent on β-LGCNP concentration. After intestinal digestion for 2 h, the release rate of free fatty acids from the Pickering emulsion was (65.17 ± 1.52)%, which was 26.65% higher than that from passion fruit seed oil. The rheological results showed a shear-thinning phenomenon, indicating that the emulsion is a non-Newtonian fluid, and the elastic and viscous moduli increased with the increase in shear frequency. During 15 days of storage, the amount of lipid oxidation products including hydroperoxide and malondialdehyde (MDA), and the rate of lipid oxidation in the Pickering emulsion decreased. In summary, the Pickering emulsion stabilized with β-LGCNPs improved the stability, antioxidant activity, digestibility and lipid oxidation of passion fruit seed oil, which is conducive to expanding the application of passion fruit seed oil in the food field.

Key words: Pickering emulsion; β-lactoglobulin; polyphenols; passion fruit seed oil; antioxidant activity; digestibility