Preparation,Characterization And Delivery Of Pickering Emulsions Stabilized By Zein-Pullulan

Citrus polymethoxy flavonoids(PMFs)possessed abundant physiological and pharmacological bioactivities activities,such as anticancer,anti-inflammatory,antioxidant,anti allergy and so on.Their research and application in food and medicine field are paid more and more attention.However,most PMFs have the characteristics of high melting point,poor water solubility and low oral bioavailability,so how to effectively add PMFs to food and drug is still facing severe challenges.The Pickering emulsions are stabilized by solid particles.Compared with traditional emulsions,they showed the advantages of better structural stability,biocompatibility,resistance to external pressure and lower toxicity to human environment,they manifested the ability to protect encapsulated bioactive substances and control their release.Zein,as the main storage protein of corn,shows amphiphilic,unique self-assembly properties and biocompatibility.In this paper,we have constructed a neutral wetting composite solid particle by using the self-assembly characteristics of Zein and the strong hydrophilicity of pullulan.We successfully prepared Pickering with gel properties stabilized by zein/pullulan complex colloidal particles for the first time.We further utilizing the emulsion to load three kind of PMFs,are bioactive substances with nutritional functions but with low bioavailability,were used to simulate the in vitro digestion to evaluate the potential impact of the emulsion delivery system on the bioavailability.The main results are as follows:1.Based on the unique self-assembly characteristics of zein,zein-pullulan complex colloidal particles were successfully prepared by a simple anti solvent method and characterized.The appearance,potential,particle size,turbidity and thermal stability of complex colloidal particles were investigated by controlling the quality of pullulan.The presence of pullulan increased the size,decreased zeta and provided excellent resistance to gravitational separation of zein.Moreover,through the three phase antennae to research hydrophilicity of complex colloidal particles,the results showed that the hydrophobicity of zein was modified by hydrophilic pullulan to endow the ZPPs with nearly neutral wettability when the mass ratio was 15:1.The morphology of the composite solid particles was observed by scanning electron microscopy,the results showed that the composite solid particles were round,and the composite particles were easy to coalesce,flocculate or even connect into pieces under the condition of high proportion of pullulan.The structure of the composite colloidal particles was further studied by infrared technology,indicated hydrogen bond force was formed between protein a nd pullulan.2.The Pickering emulsions with different oil volume fraction were prepared with different mass ratio of zein-pullulan complex colloidal particles as stabilizer.The appearance,droplet size and storage stability of the emulsion were preliminaril y studied,and the viscoelasticity of the emulsion was further analyzed by rheological properties.The distribution and stability of the composite solid particles at the emulsion water and oil interface were investigated by optical microscopy and laser scanning confocal microscopy.The results showed that the presence of pullulan significantly reduced the particle size of the emulsion.The higher the oil phase,the larger the droplet size.The microscopic structure observation showed that the droplets were clearly demarcated,tightly connected and extruded,and a large number of protein molecules adsorbed on the oil-water interface to form a dense protective layer,thus forming a stable Pickering emulsion which could store for more than three months with strong stability and possess gel network structure.3.Using the Pickering emulsion prepared by zein-pullulan complex colloidal particles as carrier and encapsulating three kinds of PMFs.The antioxidant properties of three kinds of PMFs and the rheological properties of emulsions were studied,and the oil antioxidant properties and digestion characteristics of the emulsion were further explored.The results showed that the emulsion encapsulated with three kinds of PMFs possessed good rheological properties and still exhibited the high strength gel network structure inside the emulsion.The antioxidant properties of PMFs were enhanced by the emulsion delivery system.By measuring the content of hydroperoxide and malondialdehyde in the emulsion,indicating that the emulsion showed good anti-lipid oxidation characteristics.The results of simulated gastrointestinal tract showed that the emulsion encapsulated with three kinds of PMFs possessed higher hydrolysis degree during the digestion process,and could improve the bioavailability of the three three kinds of PMFs at the same time.