Robust W/O/W Emulsion Stabilized by Genipin-Cross-Linked Sugar Beet Pectin-Bovine Serum Albumin Nanoparticles: Co-encapsulation of Betanin and Curcumin.

Betanin and curcumin hold promise as natural colorants and antioxidants for food purposes due to their anti-hypertensive, anti-inflammation, and anti-tumor effects. However, the thermal stability and bioavailability of betanin and curcumin still need improvement. Here, we fabricated sugar beet pectin-bovine serum albumin nanoparticles (SBNPs) with a mean particle size of 180 ± 5.2 nm through a genipin cross-linking strategy to stabilize a type of Pickering water-in-oil-in-water (W/O/W) emulsion and co-encapsulated betanin and curcumin. First, the W1/O emulsion was homogenized with gelatin (the gelling agent) in the water phase and polyglycerol polyricinoleate (a lipophilic surfactant) in the oil phase. Later, W1/O was homogenized with another water phase containing SBNPs. The microstructure of the emulsion was regulated by the particle concentration (c) and W1/O volume fraction (Φ), especially the gel-like high internal phase emulsions were formed at the Φ up to 70%. In this case, betanin was encapsulated in the internal water phase (encapsulation efficiency = 65.3%), whereas curcumin was in the medium-chain triglyceride (encapsulation efficiency = 84.1%). Meanwhile, the shelf stability of betanin and curcumin was improved. Furthermore, the stability of bioactive compounds was potentiated by an emulsion gel in simulated gastrointestinal digestion, resulting in higher bioaccessibility. The aforementioned results suggest that SBNP-stabilized Pickering W/O/W emulsions could be a potential alternative to co-encapsulate betanin and curcumin with enhancement of shelf stability and bioaccessibility.

Synthesis of novel magnetic cellulose-chitosan composite microspheres and their application in laccase immobilization.

Novel magnetic cellulose-chitosan composite microspheres were prepared by sol-gel transition method using ionic liquids as solvent for dissolution and regeneration. Subsequently, the composite microspheres activated by glutaradehyde to immobilize enzyme. Which of their structure, properties and morphology were studied by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and vibrating-sample magnetometer showed Fe3O4 nanoparticles with mean size of -10 nm were successfully embedded in the composite microspheres. The microshpheres were examined to be with the mean size of 20 µm and good magnetic property with saturation magnetization of 30.1 emu g(-1). The effect of pH and temperature on the immobilization of laccase was also investigated. Compared with free laccase, the pH, thermal and operational stabilities of the immobilized laccase were improved and the activity recovery of immobilized laccase reached 80.6%. Immobilized laccase retained 88.9% activity after 12 reaction cycles. Therefore, the cellulose-chitosan composite microspheres were expected to be a novel support for enzyme immobilization.