Formation And Properties Of Pickering Emulsion Stabilized By Natural Legume Extract

Pickering emulsion generally refers to the emulsion stabilized by solid particles.The Pickering emulsion that uses oil and water as two phases has been extensively studied.At present,the new water-in-water Pickering emulsion in which both phases are aqueous solutions has also attracted the attention of researchers.Oil-in-water or water-in-oil Pickering emulsion has been widely used in petrochemical,interfacial catalysis,food and other fields with the characteristics of high stability and low toxicity.New water-in-water Pickering emulsion has important application value in artificial cell simulation,tissue engineering,food,medicine and other fields due to the advantages of excellent biocompatibility and biodegradability.Therefore,the research on Pickering emulsion has always been the focus of scientific research of researchers.The research on Pickering emulsion in this thesis mainly includes two parts:one part is to prepare a pomegranate seed oil-in-water Pickering emulsion with natural legume extract as stabilizers,which provides a new particulate stabilizers prepared by a green and simple method with good emulsification effect for preparing Pickering emulsion;the other part is to prepare a water-in-water Pickering emulsion with natural legume extract as stabilizers,polyethylene oxide(PEO)phase and dextran(Dex)phase as two aqueous phases.Water-in-water emulsions are difficult to stabilize due to the extremely small interfacial tension and the large interfacial thickness of the water/water interface.Preparation of natural legume extract as stabilizers of the water-in-water emulsion provides an effective and novel design idea for the preparation of particulate stabilizers of the water-in-water emulsion.The results of this thesis can promote the preparation,research and development of particulate stabilizers based on natural materials of oil-in-water Pickering emulsion and water-in-water Pickering emulsion,and greatly enrich the types of biological and environmentally friendly emulsions.This thesis is mainly composed of the following parts:In the Chapter I,introduction,the basic concept,stabilization mechanisms,particulate stabilizers and applications related to Pickering emulsion are introduced.Among them,the particulate stabilizers based on natural materials of Pickering emulsion and the stability mechanism of water-in-water Pickering emulsion are discussed in detail.Starting from the current research focus and problems,the main research purpose,contents and significance of this thesis are drawn.In the Chapter II,a kind of nanoparticles were prepared from mung beans through the steps of boiling mung beans,centrifugation,freeze-drying,etc.The results show that the particles are spherical particles with a diameter of 100-250 nm,and the main components are polysaccharides and proteins.Then the pomegranate seed oil-in-water Pickering emulsion with pomegranate seed oil and water as two phases and the particles as stabilizers was successfully prepared.And the effects of particles concentration,oil phase volume fraction,pH of the aqueous phase,ionic strength,oil phase types,particles source and other factors on the properties of the emulsion were studied.Finally,the stability and oxidation resistance of the emulsion were studied.The results show that the particles based on mung beans have good emulsifying properties on stabilizing the emulsion.Emulsion can be formed under acidic,neutral conditions or certain ionic strength.Replacing the pomegranate seed oil with an oil phase such as food-grade white oil or replacing the particles based on mung beans with the particles based on red beans in the pomegranate seed oil-in-water Pickering emulsion can still form a relatively stable emulsion.After optimizing the conditions,the emulsion has good stability within 30 days.In addition,the emulsion also has strong antioxidant capacity.The results of this chapter provide a simple and green method for the preparation of particulate stabilizers based on natural materials of Pickering emulsion,and expand ideas for constructing biological and environmentally friendly Pickering emulsions.In Chapter Ⅲ,we prepared the water-in-water Pickering emulsion with the above-mentioned nanoparticles based on mung beans as stabilizers and dextran(Dex)phase and polyethylene oxide(PEO)phase as two aqueous phases.The effects of particles concentration,PEO/Dex concentration on the properties of the emulsion and the stability of the emulsion were studied.The results show that the particles have good emulsifying properties for the water-in-water emulsion.After standing for one day,the emulsions formed in different concentrations of two aqueous phases are all Dex-in-PEO(PEO/Dex)type.After optimizing the conditions,the macroscopic state of the emulsion and the size of the emulsion droplets change little within 15 days,and the stability is good.The water-in-water Pickering emulsion is a biological and environmentally friendly emulsion,and has application potential in food,medicine,cosmetics,tissue engineering and other fields.