The effects of different temperature-time regimes of enzymatic retrogradation on the particle size, microscopic morphology, crystal structure, functional groups and epigallocatechin-3-gallate (EGCG)-loading capacity of debranched starch nanoparticles (DBS-NPs) prepared with green banana starch were investigated. Meanwhile, the stability, antioxidant properties and in vitro release behavior of EGCG@DBS-NPs were investigated. It was shown that compared with green banana starch, the particle size of DBS-NPs decreased from (23.4 ± 7.3) μm to (208.5 ± 2.7) nm, and the crystal structure changed from type C to C→B or C→A. Besides, the relative crystallinity and the hydrogen bonding force between molecular chains were enhanced. EGCG showed the highest loading capacity (4.34%) and encapsulation efficiency (86.89%) in DBS-NP50-12, and their combination exhibited synergistic antioxidant activity. EGCG@DBS-NP50-12 was found to be more stable in a near neutral environment than in an acidic environment, and significantl more stable than free EGCG during storage. EGCG@DBS-NP50-12 exhibited excellent slow release behavior in vitro, which was fitted to a first-order kinetic equation. This study provides a reference for the preparation and application of starch nanoparticles, which has potential value in the construction of starch-based bioactive carriers.

In order to investigate the impact of ozone pretreatment and lipid modification on the structure and properties of starch, ozone-pretreated banana starch-lauric acid complexes were prepared and their physicochemical properties and digestibility were evaluated. Results showed that in comparison with the native starch, the complexation index (CI) of the pretreated starch with lauric acid increased by 12.67%; the resulting complexes exhibited a significant increase in water solubility, swelling power and syneresis, an elevation in gelatinization temperature from 104.24–135.23 ℃ to 155.60–161.68 ℃ , and a 6.71% increase in resistant starch, but a decrease in iodine binding capacity. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) demonstrated that lauric acid was bound to the surface of starch granules to form a complex, thereby increasing the surface height of starch granules. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) revealed that banana starch and lauric acid formed non-V-type and V-type complexes through hydrogen bonding and hydrophobic interactions. The results of contact angle and thermogravimetric (TG) analysis demonstrated that the hydrophobic properties and thermal stability of the complexes were improved. Consequently, the combination of ozone pretreatment and lauric acid modification could enhance the water solubility, swelling capacity, and thermal stability of banana starch, further improving its digestibility resistance. These findings will expand the application potential of starch in the food field.

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.