Studies On The Preparation Of Modified Soybean Cellulose And Properties Of Pickering Emulsion

China has rich resources of soybean residue,with an annual output of 2.8 milion tons.Soybean residue contains rich protein(about 15%)and cellulose(above 70%).The hydrophilicity and insolubility of soybean dietary fiber would make it a good stabilizer for Pickering emulsion.Recently,more and more studies have been focused on food grade Pickering emulsion stabilized by protein,starch,cellulose owing to its good stability and environmentally friendly properties.Few reports of soybean dietary fiber as a Pickering stabilizer have been found.In the present work,residual proteins in soybean residue were removed using an ultrasonication-assisted hot alkali method,then the purified soybean dietary fibers were used to prepare Pickering emulsions.The effects of different factors(soybean dietary fiber concentration,oil mass fraction,pH value and ionic strength of bulk phase)on the properties of Pickering emulsions stabilized by soybean dietary fiber were firstly investigated.On this basis,we further used hydrophobic food grade ethyl cellulose to graft soybean dietary fiber to prepare modified fiber and O/W Pickering emulsion.The effect of hydrophobic modification on the structures,properties of soybean dietary fiber and its Pickering emulsion characteristics were comparatively studied.We hope to develop an edible Pickering particle and explore a way of green modification,providing the theory and method guidance for the comprehensive utilization of soybean residue and the preparation of food-grade Pickering particles using soybean residue.The ultrasonication-assisted hot alkali method could effectively remove residual proteins in soybean residue,and improve the structure and properties of soybean dietary fiber.We firstly use this method to remove residual proteins because the high amounts of residual proteins would heavily influence the properties of emulsion stabilized by soybean dietary fiber.The structure and characteristics of purified soybean dietary fiber were also investigated.The results show that most of proteins can be effectively removed from the soybean dietary fiber by heating soybean residue at 110 ? for 30 min in the solid-liquid ratio of 20 mL/g,pH value of 12.In addition,the decrease of polymerization degree and the increase of its hydrophobicity,water/oil retention capacity as well as swelling capacity were alsodiscovered.Soybean dietary fiber exhibits a great potential in forming and stabilizing Pickering emulsion.We use the homemade soybean dietary fiber to prepare Pickering emulsion and study its properties and stability.The results indicate that the emulsions could be stabilized well when the particle concentration is in the range of 0.4-0.5 wt%,or the oil mass fraction is less than 20%.The pH value and ionic strength have few effects on the coalescence stability of emulsions.The stability of emulsions in high ionic strength is better than it in low ionic strength.The creaming stability declined when the emulsion is in acidic or alkaline conditions or when salt ions exist.The emulsion exhibits shear thinning and weak gel behaviors,and its gel structure is strengthened with the storage time prolongs.Hydrophobic modification with ethyl cellulose could further improve the structure and characteristics of soybean dietary fiber,meanwhile significantly enhance the properties and stability of its Pickering emulsion.We use soybean dietary fiber graft ethyl cellulose to prepare modified fiber and use it to stabilize O/W Pickering emulsion.The structure and characteristics of modified fiber and properties and stability of Pickering emulsion were also investigated.It is conspicuous that ethyl cellulose could further increase the hydrophobicity,water retention capacity,oil retention capacity,foaming ability and interfacial activity of soybean dietary fiber.The creaming stability of emulsions stabilized by modified fiber is higher than that stabilized by soybean dietary fiber in any conditions.The coalescence stability of emulsions stabilized by modified fiber is higher than that stabilized by soybean dietary fiber when the particle concentration is more than 0.4%,or at acidic or neutral pH value.