Fuge Niu

Ovalbumin-gum arabic interactions: effect of pH, temperature, salt, biopolymers ratio and total concentration.

The formation of soluble and insoluble complexes between ovalbumin (OVA) and gum arabic (GA) polysaccharide was investigated under specific conditions (pH 1.0-7.0; temperature 4-55 °C; NaCl concentration 0-60mM; total biopolymer concentration 0.05-3.0 wt%) by turbidimetric analysis. For the 2:1 OVA:GA ratio and in the absence of NaCl, soluble and insoluble complexes were observed at pH 4.61 (pHφ1) and 4.18 (pHφ2), respectively, with optimal biopolymer interactions occurring at pH 3.79 (pHopt). Under the same conditions, OVA alone gave only a weak turbidity intensity (turbidity <0.03), whereas GA had none. As the temperature increased, critical pH values shifted toward lower pH, and the maximum turbidity value occurred at 25 °C. The region between pHφ1 and pHφ2 was narrowed and the electrostatic interactions became weaker with increasing NaCl concentration. The maximum turbidity value increased as the total biopolymer concentration increased until reaching a critical value (2.0%), afterwards becoming a constant value.

Synthesis, characterization, and application of Fe3O4@SiO2–NH2 nanoparticles

Magnetic Fe3O4@SiO2–NH2 nanoparticles were synthesized, characterized and applied as magnetic adsorbing carriers in this paper to separate ovotransferrin (OVT) from chicken egg white. The properties of the particles were characterized, and the results showed that silica shell and terminal amino groups were successfully appended to the Fe3O4 core; the mean diameter of the modified particles was about 210 nm and the isoelectric point (pI) was approximately 9.25; in addition the particles displayed desirable magnetic properties, excellent dispersibility and high stability. The particles performed satisfactorily in the separation of OVT and the maximum adsorption loading reached 77.2 mg g−1 in 30 min at 40 °C. Moreover Fe3O4@SiO2–NH2 nanoparticles were very stable after repeated adsorption–desorption experiments. OVT separated by Fe3O4@SiO2–NH2 nanoparticles displayed strong ability of binding iron and had a high purity. Besides, the recovery of OVT separated from egg white was calculated to be 84.62%. In addition, the nanoparticles showed desirable repeatability in repeated adsorption–desorption experiments. Hence Fe3O4@SiO2–NH2 nanoparticles were promising to scale up the separation of OVT from chicken egg white due to the huge advantages of high dispersion, high reactivity, and easy separation.

Comparison of a novel TiO2/diatomite composite and pure TiO2 for the purification of phosvitin phosphopeptides

A novel TiO2/diatomite composite (TD) was prepared and then characterized by scanning electron microscope (SEM) and Fourier Transform Infrared (FTIR). The results of SEM showed that after modification, the porous surface of diatomite was covered with TiO2. Both diatomite and TD had clear disc-shaped structures with average grain diameters of around 25 μm. Then TD and pure TiO2 were applied in the purification of phosvitin phosphopeptides (PPPs) from the digest of egg yolk protein, and a comparative study of adsorption properties of PPPs on TD and TiO2 was performed. In the study of adsorption kinetics, the adsorption equilibrium of PPPs on TD and TiO2 fitted well with the Langmuir model, and the time needed to reach adsorption equilibrium were both around 10 min. The maximum dynamic adsorption capacity of TD (8.15 mg/g) was higher than that of TiO2 (4.96 mg/g). The results of repeated use showed that TD and TiO2 were very stable after being subjected to ten repeated adsorption-elution cycles, and TD could easily be separated from aqueous solution by filtration. On the other hand, the present synthetic technology of TD was very simple, cost-effective, organic solvent-free and available for large-scale preparation. Thus, this separation method not only brings great advantages in the purification of PPPs from egg yolk protein but also provides a promising purification material for the enrichment of phosphopeptides in proteomic researches.

Purification of phosvitin phosphopeptides using macro-mesoporous TiO2

Macro-mesostructured titanium dioxide (MMTD) was synthesized, characterized and applied as an adsorbent in the purification of phosvitin phosphopeptides (PPPs) from egg-yolk protein hydrolysates successfully. The synthesized material was analyzed using Fourier transform infrared spectroscopy (FT-IR), nitrogen adsorption–desorption analysis and scanning electron microscopy (SEM). The resultant MMTD exhibited a uniform macroporous structure with worm-like mesoporous walls, and the particle sizes were around 22 μm with the facility to be separated from aqueous solution. In the purification process, the adsorption of PPPs onto MMTD fitted well with the Freundlich model and pseudo-second-order kinetics model, and the maximum adsorption capacity reached 36.47 mg g−1 in 20 min when the crude polypeptide concentration was 16 mg mL−1. The purity of the obtained PPPs was relatively high with a nitrogen/phosphorus molar ratio (N/P) of 5.4. Moreover, the reusability of MMTD was satisfying in the twenty repeated adsorption–desorption cycles. Hence, the purification of PPPs using MMTD was highly efficient and could be scaled-up for practical application.